Anatomy and Physiology

An Introduction to Anatomy and Physiology

The basic functions of organisms
•      Organization      
•      Responsiveness
•      Growth and differentiation    
•      Reproduction
•      Movement
•      Metabolism and excretion

The Specialties of Anatomy
•      Gross Anatomy
•    Surface anatomy
•    Regional anatomy
•    Systemic anatomy
•    Developmental anatomy
•      Microscopic anatomy
•    Cytology
•    Histology

Comparative Anatomy
•      All vertebrates share a basic pattern of organization, most noticeable during embryology.

The Specialties of Physiology
•      Cell physiology
•      Special physiology
•      Systemic physiology
•      Pathological physiology

Levels of Organization
•      Integumentary system
•      Nervous system
•      Skeletal system
•      Endocrine system
•      Muscular system
•      Cardiovascular system
•      Lymphatic system
•      Urinary system
•      Respiratory system
•      Digestive system
•      Reproductive system


Homeostasis:

Two general points within homeostasis
•      Autoregulation
•      Extrinsic regulation

Homeostatic regulation involves
•      A receptor
•      A control center
•      An effector


Negative Feedback: Example--The Control of Body Temperature

Positive Feedback: Example--Blood Clotting


Language of Anatomy
Anatomical position – standing upright with palms facing forward : A frame of reference for anatomical studies
•      Superficial anatomy breaks the body into anatomical landmarks and regions
•      Sectional anatomy provides directional references

Anatomical Landmarks

Abdominopelvic Quadrants and Regions

Directional References

Planes and Sections are important in visualizing structures
•      Transverse plane divides the body into superior  and inferior
•      Frontal (coronal) plane divides the body into anterior and posterior
•      Sagittal plane divides the body into left and right
•    Midsagittal divides the body exactly down the middle

Body Cavities
•      Body cavities are internal chambers holding vital organs
•    Cavities protect vital organs
•    Cavities allow organs to change in shape and size
•      Two body cavities
•    Dorsal body cavity includes the cranial cavity and the spinal cavity
•    Ventral body cavity includes the thoracic cavity and the abdominopelvic cavity

Thoracic Cavities
•      The thoracic cavity contains the heart and lungs.
•      It is subdivided into the left and right pleural cavities and the mediastinum
•    Each pleural cavity contains one lung lined by the visceral and parietal pleura
•    The mediastinum contains the pericardium, another serous membrane that surrounds the heart

Abdominopelvic Cavity
•      The abdominopelvic cavity is lined by the peritoneum
•    The abdominal cavity extends from the diaphragm to the superior margins of the pelvis
•   liver, stomach, spleen and most of the large intestine
Abdominopelvic Cavity
•    The pelvic cavity is bordered by the pelvis, with a floor of muscle
•   reproductive organs, urinary bladder and the final portion of the large intestine

Clinical technology allows many different views of the body
•      X-rays
•      Computerized tomography (CT) scans
•      Magnetic resonance imaging (MRI) scans
•      Ultrasound images
•      Spiral CT scans
•      Digital subtraction angiography images (DSA)
•      Positron emission tomography (PET) scans
The Chemical Level of Organization


Atoms, Molecules and Bonds
Atoms are the smallest stable units of matter
•      Subatomic particles
•    Protons = positive charge; weight of approximately 1 Dalton
•    Neutrons = no charge; weight similar to protons
•    Electrons = negative charge; weigh 1/1836th Dalton
•    Protons and neutrons are found in the nucleus; electrons occupy electron cloud
•      Atomic number = proton number; atomic mass = protons and neutrons
•    Isotopes are elements with similar numbers of protons but different numbers of neutron

Electrons occupy a series of energy levels or electron shells.
•      The outermost electron shell determines the reactivity of the element.

Atoms combine through chemical reactions
•      Molecule = a chemical structure consisting of molecules held together by covalent bonds
•      Compound = a chemical substance composed of atoms of two or more elements
•      There are three types of bond: Ionic, covalent, and hydrogen

Ionic Bonding
•    Exchange of electrons from one atom to another Ionic = attraction between positive cations and negative anions

Covalent bonds exist between atoms that share electrons to form a molecule
•      Double covalent bond
•      Non-polar covalent bond
•      Polar covalent bond
Hydrogen bonds are weak forces that affect the shape and properties of compounds
•      Polar covalent bonds that occur when hydrogen covalently bonds with another element

Matter and chemical notation
•      Matter can exist as a solid, liquid or gas
•    Depends on the interaction of the component atoms or molecules
•    Molecular weight is the sum of the atomic weights of the component atoms
•      Chemical notation
•    Short-hand that describes chemical compounds and reactions

Chemical Reactions

A chemical reaction occurs when reactants combine to generate one or more products
•      All chemical reactions in the body constitutes metabolism
•      Metabolism provides for the capture, storage and release of energy

Basic energy concepts
•      Work = movement of an object or change in its physical structure
•      Energy = the capacity to perform work
•      Kinetic energy is energy of motion
•      Potential energy is stored energy resulting from position or structure
•    Conversions are not 100% efficient, resulting in release of heat

Metabolism
•      Types of reaction
•    Decomposition
•    Synthesis
•    Exchange
•      Metabolism is the sum of all reactions
•    Through catabolism cells gain energy (break down of complex molecules)
•    Anabolism uses energy (synthesis of new molecules)

Reversible reactions
•      All reactions are theoretically reversible
•      At equilibrium the rates of two opposing reactions are in balance
•    Anabolism = catabolism

Enzymes, energy and chemical reactions
•      Activation energy is the amount of energy needed to begin a reaction
•      Enzymes are catalysts
•    Reduce energy of activation without being permanently changed or used up

Inorganic Compounds
Nutrients and Metabolites
•      Nutrients are essential chemical compounds obtained from the diet
•      Metabolites are molecules synthesized or broken down inside the body
•      These can be classified as organic or inorganic compounds
•    Organic compounds have carbon and hydrogen as their primary structural component
•    Inorganic compounds are not primarily carbon and hydrogen

Water and its properties
•      Water is the most important constituent of the body
•    Solution is a uniform mixture of two or more substances
•    Solvent is the medium in which molecules of solute are dispersed
•    Water is the solvent in aqueous solutions

Electrolytes undergo ionization
•      Compounds that interact readily with water are hydrophilic
•      Compounds that do not interact with water are hydrophobic

pH is a measure of the concentration of hydrogen ions solution
•      Neutral
•      Acidic
•      Basic

Acids and Bases
•      Acids release hydrogen ions into solution
•      Bases remove hydrogen ions from solution
•    Strong acids and strong bases ionize completely
•    Weak acids and weak bases do not ionize

Salts and buffers
•      Salt = an electrolyte whose cation is not hydrogen and whose anion is not hydroxide
•      Buffers remove or replace hydrogen ions in solution
•    Buffer systems maintain the pH of body fluids

Organic Compounds
Organic compounds
•      Organic compounds generally include
•    Carbon
•    Hydrogen
•    and sometimes Oxygen
•      Four major classes of organic compounds are
•    Carbohydrates
•    Lipids
•    Proteins
•    Nucleic acids
•   High energy compounds are also organic compounds

Carbohydrates
•      Important energy source for metabolism
•      Monosaccharides, disaccharides and polysaccharides
•    Di- and polysaccharides formed from monosaccharides by dehydration synthesis

Lipids include fats, oils, and waxes
•      Five classes:
•    Fatty acids
•    Eicosanoids
•    Glycerides
•    Steroids
•    Phospholipids
•    Glycolipids
•      Triglycerides = three fatty acids attached by dehydration synthesis to one molecule of glycerol

Steroids
•      Are involved in cell membrane structure
•      Include sex hormones and hormones regulating metabolism
•      Are important in lipid digestion

Proteins perform many vital functions in the body. The six important types are:
•      Structural proteins
•      Contractile proteins
•      Transport proteins
•      Enzymes
•      Buffering proteins
•      Antibodies

Proteins are chains of amino acids
•      Amino acids contain an amino group, a carboxylic group and a radical group
•      Polypeptides are linear sequences of amino acids held together by peptide bonds

The four levels of protein structure are:
•      Primary structure (amino acids sequence)
•      Secondary structure (amino acid interactions)
•      Tertiary structure (complex folding)
•      Quaternary structure (protein complexes)

Enzyme reactions
•      Reactants (substrate) interact to yield a product by binding to the active site of the enzyme
•      Cofactors must bond to the enzyme before substrate binding can occur
•      Coenzymes are organic cofactors commonly derived from vitamins

The shape of a protein determines its function
•      Proteins pushed outside their optimal temperature and pH range become temporarily or permanently denatured and will cease to function

Nucleic acids
•      Store and process information at the molecular level
•      Made of purines and pyrimidines
•      DNA and RNA

Nucleic acids are chains of nucleotides
•      Nucleotides are composed of a sugar, a phosphate and a nitrogenous base
•    Sugar = deoxyribose (DNA) or ribose (RNA)
•    DNA Bases = adenine, thymine, cytosine, guanine
•    RNA bases = adenine, uracil, cytosine, guanine

High energy compounds store cellular energy in high energy bonds
•      Adenosine triphosphate (ATP)
•    Made by adding a phosphate group to adenosine diphosphate (ADP)
•    Process referred to as phosphorylation

Chemicals and Cells
Biochemical compounds form functional units called cells
•      Metabolic turnover allows cells to change and to adapt to changes in their environment
The Cellular Level of Organization

An Introduction to Cells
The cell theory states:
•      Cells are the building blocks of all plants and animals
•      Cells are produced by the division of preexisting cells
•      Cells are the smallest units that perform all vital physiological functions
•      Each cell maintains homeostasis at the cellular level
•    Homeostasis at higher levels reflects combined, coordinated action of many cells

Cell biology
•      Cytology, the study of the structure and function of cells
•    The human body contains both somatic and sex cells

A typical cell
•      Is surrounded by extracellular fluid, which is the interstitial fluid of the tissue
•      Has an outer boundary called the cell membrane or plasma membrane

The Cell Membrane
Cell membrane functions include:
•      Physical isolation
•      Regulation of exchange with the environment
•      Structural support
•      The cell membrane is a phospholipid bilayer with proteins, lipids and carbohydrates.

Membrane proteins include:
•      Integral proteins
•      Peripheral proteins
•      Anchoring proteins
•      Recognition proteins
•      Receptor proteins
•      Carrier proteins
•      Channels

Membrane carbohydrates form the glycocalyx
•      Proteoglycans
•      Glycolipids
•      Glycoproteins


The Cytoplasm
The cytoplasm contains:
•      The fluid (cytosol)
•      The organelles the cytosol surrounds
Organelles
•      Nonmembranous organelles are not enclosed by a membrane and always in touch with the cytosol
•    Cytoskeleton, microvilli, centrioles, cilia, ribosomes, proteasomes
•      Membranous organelles are surrounded by lipid membranes
•    Endoplasmic reticulum, Golgi apparatus, lysosomes, peroxisomes, mitochondria

Cytoskeleton provides strength and flexibility
•      Microfilaments
•      Intermediate filaments
•      Microtubules
•      Thick filaments

Microvilli
•        increase surface area

Centrioles
•      Direct the movement of chromosomes during cell division
•      Organize the cytoskeleton
•      Cytoplasm surrounding the centrioles is the centrosome

Cilia
•      Is anchored by a basal body
•      Beats rhythmically to move fluids across cell surface

Ribosomes
•      Are responsible for manufacturing proteins
•      Are composed of a large and a small ribosomal subunit
•      Contain ribosomal RNA (rRNA)
•      Can be free or fixed ribosomes

Proteasomes
•      Remove and break down damaged or abnormal proteins
•      Require targeted proteins to be tagged with ubiquitin

Endoplasmic reticulum
•      Intracellular membranes involved in synthesis, storage, transportation and detoxification
•      Forms cisternae
•      Rough ER (RER) contains ribosomes
•     Forms transport vesicles
•      Smooth ER (SER)
•     Involved in lipid synthesis

Golgi Apparatus
•      Forms secretory vesicles
•    Discharged by exocytosis
•      Forms new membrane components
•      Packages lysosomes

Lysosomes and Peroxisomes
•      Lysosomes are
•    Filled with digestive enzymes
•    Responsible for autolysis of injured cells
•      Peroxisomes
•    Carry enzymes that neutralize toxins

Membrane flow
•      Continuous movement and recycling of membranes
•    ER
•    Vesicles
•    Golgi apparatus
•    Cell membrane
Mitochondria
•      Responsible for ATP production through aerobic respiration
•      Matrix = fluid contents of mitochondria
•      Cristae = folds in inner membrane



The Nucleus
The nucleus is the center of cellular operations
•      Surrounded  by a nuclear envelope
•    Perinuclear space
•      Communicates with cytoplasm through nuclear pores

Contents of the nucleus
•      A supportive nuclear matrix
•      One or more nucleoli
•      Chromosomes
•    DNA bound to histones
•    Chromatin

The genetic code
•      The cells information storage system
•      Triplet code
•      A gene contains all the triplets needed to code for a specific polypeptide

Gene activation and protein synthesis
•      Gene activation initiates with RNA polymerase binding to the gene
•      Transcription is the formation of mRNA from DNA
•    mRNA carries instructions from the nucleus to the cytoplasm

Translation is the formation of a protein
•      A functional polypeptide is constructed using mRNA codons
•    Sequence of codons determines the sequence of amino acids
•    Complementary base pairing of anticodons (tRNA) provides the amino acids in sequence

How Things Get Into and Out of Cells
Permeability
•      The ease with which substances can cross the cell membrane
•    Nothing passes through an impermeable barrier
•    Anything can pass through a freely permeable barrier
•    Cell membranes are selectively permeable

Diffusion
•      Movement of a substance from an area of high concentration to low
•      Continues until concentration gradient is eliminated

Osmosis
•      Diffusion of water across a semipermeable membrane in response to solute differences
•      Osmotic pressure = force of water movement into a solution
•      Hydrostatic pressure opposes osmotic pressure
•      Water molecules undergo bulk flow

Tonicity
•      The effects of osmotic solutions on cells
•      Isotonic = no net gain or loss of water
•      Hypotonic = net gain of water into cell
•    Hemolysis
•      Hypertonic = net water flow out of cell
•    Crenation

transport
•      Carrier mediated transport
•    Binding and transporting specific ions by integral proteins
•   Cotransport
•   Counter-transport
•      Facilitated diffusion
•    Compounds to be transported bind to a receptor site on a carrier protein

Active transport
•      Active transport
•    Consumes ATP
•    Independent of concentration gradients
•      Types of active transport include
•    Ion pumps
•    Secondary active transport

Vesicular transport: material moves into or out of cells in membranous vesicles
•      Endocytosis is movement into the cell
•     Receptor mediated endocytosis (coated vesicles)
•     Pinocytosis
•     Phagocytosis (pseudopodia)
•      Exocytosis is ejection of materials from the cell

The transmembrane potential
•      Difference in electrical potential between inside and outside a cell
•      Undisturbed cell has a resting potential


The Cell Life Cycle
cell division
•      Cell division is the reproduction of cells
•      Apoptosis is the genetically controlled death of cells
•      Mitosis is the nuclear division of somatic cells
•      Meiosis produces sex cells
Interphase
•      Most somatic cells spend the majority of their lives in this phase
•      Interphase includes
•    G1
•    S
•    G2

Mitosis, or nuclear division, has four phases
•      Prophase
•      Metaphase
•      Anaphase
•      Telophase

Mitotic rate and cancer
•      Generally, the longer the life expectancy of the cell, the slower the mitotic rate
•    Stem cells undergo frequent mitoses
•    Growth factors can stimulate cell division
•    Abnormal cell division produces tumors or neoplasms
•   Benign
•   Malignant (invasive, and cancerous)
•   Spread via metastasis
•   Oncogenes

Differentiation
•      Process of specialization
•      Results from inactivation of particular genes
•      Produces populations of cells with limited capabilities
•      Differentiated cells form tissues
The Tissue Level of Organization


Tissues and tissue types
•      Tissues are:
•    Collections of specialized cells and cell products organized to perform a limited number of functions
•   Histology = study of tissues
•      The four tissue types are:
•    Epithelial
•    Connective
•    Muscular
•    Nervous

Epithelial tissue
•      Includes glands and epithelium
•    Glands are secretory
•      Is avascular
•      Forms a protective barrier that regulates permeability
•      Cells may show polarity

Functions of epithelium
•      Physical protection
•      Control permeability
•      Provide sensation
•      Produce specialized secretions

Specializations of epithelium
•      Perform secretory functions
•      Perform transport functions
•      Maintain physical integrity
•      Ciliated epithelia move materials across their surface

Maintaining the integrity of epithelium
•      Cells attach via cell adhesion molecules (CAM)
•      Cells attach at specialized cell junctions
•    Tight junctions
•    Desmosomes
•    Gap junctions

Structure of typical epithelium
•      Basal lamina attaches to underlying surface
•    Lamina lucida
•    Lamina densa
•      Germinative cells replace short-lived epithelial cells

Classification of epithelia
•      Number of cell layers
•    Simple
•    Stratified
•      Shape of apical surface cells
•    Squamous
•    Cuboidal
•    Columnar

Glandular epithelia
•      Exocrine glands
•    Secrete through ducts onto the surface of the gland
•      Endocrine glands
•    Release hormones into surrounding fluid

Glandular secretions can be:
•      Merocrine (product released through exocytosis)
•      Apocrine (involves the loss of both product and cytoplasm)
•      Holocrine (destroys the cell)

Glands
•      Unicellular
•    Individual secretory cells
•      Multicellular
•    Organs containing glandular epithelium
•    Classified according to structure


Connective Tissues
Connective tissue functions:
•      Establishing a structural framework
•      Transporting fluids and dissolved materials
•      Protecting delicate organs
•      Supporting, surrounding and interconnecting tissues
•      Storing energy reserves
•      Defending the body from microorganisms

Connective tissues contain
•      Specialized cells
•      Matrix
•     Composed of extracellular protein fibers and a ground substance

Connective tissue proper
•      Contains varied cell populations
•      Contains various fiber types
•      A syrupy ground substance

Fluid connective tissue
•      Contains a distinctive cell population
•      Watery ground substance with dissolved proteins
•      Two types
•    Blood
•    Lymph

Supporting connective tissues
•      Less diverse cell population
•      Dense ground substance
•      Closely packed fibers
•      Two types
•    Cartilage
•    Bone

Connective tissue proper
•      Contains fibers, a viscous ground substance, and a varied cell population
•    Fibroblasts
•    Macrophage
•    Adipocytes
•    Mesenchymal cells
•    Melanocytes
•    Mast cells
•    Lymphocytes
•    Microphages

Connective tissue proper
•      Three types of fiber
•     Collagen fibers
•     Reticular fibers
•     Elastic fibers

Connective tissue proper
•      Classified as loose or dense
•      Loose
•    Embryonic mesenchyme, mucous connective tissues
•    Areolar tissue
•    Adipose tissue
•    Reticular tissue
•      Dense
•    Dense regular CT
•    Dense irregular CT


Fluid connective tissues
•      Distinctive collections of cells in a fluid matrix
•      Blood
•    Formed elements and plasma
•   Red blood cells, white blood cells and platelets
•    Arteries carry blood away, veins carry to the heart
•    Capillaries allow diffusion into the interstitial fluid
•      Lymph
•    Interstitial fluid entering the lymphatic vessels

Supporting connective tissues
•      Cartilage and bone support the rest of the body
•      Cartilage
•    Grows via interstitial and appositional growth
•    Matrix is a firm gel containing chondroitin sulfate
•    Cells called chondrocytes
•    Cells found in lacunae
•    Perichondrium separates cartilage from surrounding tissues
•    Three types: hyaline, elastic and fibrocartilage
•      Has osteocytes
•    Depend on diffusion through canaliculi for nutrients
•      Little ground substance
•      Dense mineralized matrix
•      Surrounded by periosteum

Membranes
Membranes are simple organs
•      Form a barrier
•      Composed of epithelium and connective tissue
•      Four types
•    Cutaneous
•    Synovial
•    Serous
•    Mucous

Mucous membranes
•      Line cavities that communicate with the exterior
•      Contain lamina propria

Serous membranes
•      Line sealed internal cavities
•      Form transudate
•      Cutaneous membrane
•     Covers the body surface
•      Synovial membrane
•     Incomplete lining within joint cavities

The Connective Tissue Framework of the Body
Organs and systems are interconnected
•      Network of connective tissue proper consisting of
•    Superficial fascia
•    Deep fascia
•    Subserous fascia


Muscle Tissue
Muscle tissue
•      Specialized for contraction
•      Three types
•    Skeletal
•    Cardiac
•    Smooth

Skeletal muscle
•      Cells are multinucleate
•      Striated voluntary muscle
•      Divides via satellite cells

Cardiac muscle
•      Cardiocytes occur only in the heart
•      Striated involuntary muscle
•      Relies on pacemaker cells for regular contraction

Smooth muscle tissue
•      Non-striated involuntary muscle
•      Can divide and regenerate


Neural Tissue
Neural tissue
•      Conducts electrical impulses
•      Conveys information from one area to another

Neural tissue cells
•      Neurons
•    Transmit information
•      Neuroglia
•    Support neural tissue
•    Help supply nutrients to neurons


Neural anatomy
•      Cell body
•      Dendrites
•      Axon (nerve fiber)
•    Carries information to other neurons


Tissue Injuries and Aging
Inflammation and regeneration
•      Injured tissues respond in coordinated fashion
•      Homeostasis restored by inflammation and regeneration

Inflammatory response
•      Isolates injured area
•      Damaged cells, tissue components and dangerous microorganisms removed
•    Infection avoided
•      Regeneration restores normal function


Aging and tissue repair
•      Change with age
•      Repair and maintenance less efficient
•      Structure altered
•      Chemical composition altered

Aging and cancer incidence
•      Incidence of cancer increases with age
•      70-80% of all cases due to exposure to chemicals or environmental factors

Neural tissue


An Overview of the Nervous System
Nervous system overview
•      Nervous system
•    Provides swift, brief responses to stimuli
•      Endocrine system
•    Adjusts metabolic operations and directs long-term changes
•      Nervous system includes
•    All the neural tissue of the body
•    Basic unit = neuron

Divisions of the Nervous system
•      CNS (Central Nervous system)
•    Brain and spinal cord
•      PNS (Peripheral Nervous system)
•    Neural tissue outside CNS
•    Afferent division brings sensory information from receptors
•    Efferent division carries motor commands to effectors
•   Efferent division includes somatic nervous system and autonomic nervous system


Neurons
Neuron structure
•      Perikaryon
•    Neurofilaments, neurotubules, neurofibrils
•      Axon hillock
•      Soma
•      Axon
•      Collaterals with telodendria

Synapse
•      Site of intercellular communication
•      Neurotransmitters released from synaptic knob of presynaptic neuron

Neuron classification
•      Anatomical
•    Anaxonic
•    Unipolar
•    Bipolar
•    Multipolar

Functional
•    Sensory neurons
•   deliver information from exteroceptors, interoceptors, or proprioceptors
•    Motor neurons
•   Form the efferent division of the PNS
•    Interneurons (association neurons)
•   Located entirely within the CNS
•   Distribute sensory input and coordinate motor output

Neuroglia
Neuroglia of the Central Nervous System
•      Four types of neuroglia in the CNS
•    Ependymal cells
•   Related to cerebrospinal fluid
•    Astrocytes
•   Largest and most numerous
•    Oligodendrocytes
•   Myelination of CNS axons
•    Microglia
•   Phagocytic cells

Neuroglia of the Peripheral Nervous System
•      Two types of neuroglia in the PNS
•    Satellite cells
•   Surround neuron cell bodies within ganglia
•    Schwann cells
•   Ensheath axons in the PNS


Neurophysiology: Ions and Electrical Signals
The transmembrane potential
•      Electrochemical gradient
•    Sum of all chemical and electrical forces acting across the cell membrane
•    Sodium-potassium exchange pump stabilizes resting potential at ~70 mV

Changes in the transmembrane potential
•      Membrane contains
•    Passive (leak) channels that are always open
•    Active (gated) channels that open and close in response to stimuli

Three types of active channels
•      Chemically regulated channels
•      Voltage-regulated channels
•      Mechanically regulated channels
Graded potential
•      A change in potential that decreases with distance
•    Localized depolarization or hyperpolarization

Action Potential
•      Appears when region of excitable membrane depolarizes to threshold
•      Steps involved
•    Membrane depolarization and sodium channel activation
•    Sodium channel inactivation
•    Potassium channel activation
•    Return to normal permeability

Characteristics of action potentials
•      Generation of action potential follows all-or-none principle
•      Refractory period lasts from time action potential begins until normal resting potential returns
•      Continuous propagation
•    spread of action potential across entire membrane in series of small steps
•      salutatory propagation
•    action potential spreads from node to node, skipping internodal membrane

Axon classification
•      Type A fibers
•      Type B fibers
•      Type C fibers
•    Based on diameter, myelination and propagation speed

Muscle action potential versus neural action potential
•      Muscle tissue has higher resting potential
•      Muscle tissue action potentials are longer lasting
•      Muscle tissue has slower propagation of action potentials


Synaptic Activity
Nerve impulse
•      Action potential travels along an axon
•      Information passes from presynaptic neuron to postsynaptic cell

General properties of synapses
•      Electrical
•    Rare
•    Pre- and postsynaptic cells are bound by interlocking membrane proteins

General properties of synapses
•      Chemical synapses
•    More common
•    Excitatory neurotransmitters cause depolarization and promote action potential generation
•    Inhibitory neurotransmitters cause hyperpolarization and suppress action potentials
Cholinergic synapses
•      Release acetylcholine (ACh)
•      Information flows across synaptic cleft
•      Synaptic delay occurs as calcium influx and neurotransmitter release take appreciable amounts of time
•      ACh broken down
•    Choline reabsorbed by presynaptic neurons and recycled
•      Synaptic fatigue occurs when stores of ACh are exhausted

Other neurotransmitters
•      Adrenergic synapses release norepinephrine (NE)
•      Other important neurotransmitters include
•    Dopamine
•    Serotonin
•    GABA (gamma aminobutyric acid)

Neuromodulators
•      Influence post-synaptic cells response to neurotransmitter
•      Neurotransmitters can have direct or indirect effect on membrane potential
•    Can exert influence via lipid-soluble gases

Information Processing
Information processing
•      Simplest level of information processing occurs at the cellular level
•    Excitatory and inhibitory potentials are integrated through interactions between postsynaptic potentials

Postsynaptic potentials
•      EPSP (excitatory postsynaptic potential) = depolarization
•    EPSP can combine through summation
•   Temporal summation
•   Spatial summation
•      IPSP (inhibitory postsynaptic potential) = hyperpolarization
•      Most important determinants of neural activity are EPSP / IPSP interactions



Presynaptic inhibition
•      GABA release at axoaxonal synapse inhibits opening calcium channels in synaptic knob
•    Reduces amount of neurotransmitter released when action potential arrives

Presynaptic facilitation
•      Activity at axoaxonal synapse increases amount of neurotransmitter released when action potential arrives
•    Enhances and prolongs the effect of the neurotransmitter

Rate of generation of action potentials
•      Neurotransmitters are either excitatory or inhibitory
•    Effect on initial membrane segment reflects an integration of all activity at that time
•      Neuromodulators alter the rate of release of neurotransmitters

Rate of generation of action potentials
•      Can be facilitated or inhibited by other extracellular chemicals
•      Effect of presynaptic neuron may be altered by other neurons
•      Degree of depolarization determines frequency of action
•      potential generation
The Brain and Cranial Nerves


An Introduction to the Organization of the Brain
Major regions and landmarks
•      Six regions in the adult brain
•    Cerebrum
•    Diencephalon
•    Mesencephalon
•    Pons
•    Cerebellum
•    Medulla oblongata
•      Brain contains extensive areas of neural cortex
•    Layer of gray matter on the surface of the cerebellum and cerebrum

Embryology of the brain
•      Brain forms from three swellings at the tip of the developing neural tube
•    Prosencephalon
•   Forms the telencephalon and eventually the cerebrum and diencephalon
•    Mesencephalon
•    Rhombencephalon
•   Forms the metencephalon (cerebellum and pons) and myelencephalon (medulla oblongata)

Ventricles of the brain
•      Central passageway of the brain enlarges to form ventricles
•    Contain cerebrospinal fluid (CSF)

Protection and Support of the Brain
The cranial meninges
•      Continuous with the three layers of the spinal cord
•      Folds of dura mater help stabilize the position of the brain
•    Falx cerebri
•    Tentorium cerebelli
•    Falx cerebelli

Cerebrospinal fluid (CSF)
•      CSF cushions delicate neural structures
•      Supports the brain
•      Transports nutrients, chemical messengers, and waste products
•      Pathway of CSF
•    Produced at the Choroid plexus,
•    Travels through the lateral and medial apertures to the subarachnoid space,
•    Diffuses across the arachnoid granulations into the superior sagittal sinus

Blood supply to the brain
•      Blood brain barrier isolates neural tissue from general circulation
•      Incomplete barrier in areas
•    Parts of the hypothalamus
•    Pituitary gland
•    Pineal gland
•    Choroid plexus


The Medulla Oblongata
Medulla oblongata
•      Connects the brain with the spinal cord
•      Contains relay stations and reflex centers
•    Olivary nuclei
•    Cardiovascular and respiratory rhythmicity centers
•      Reticular formation begins in the medulla oblongata and extends into more superior portions of the brainstem

The Pons
The pons contains
•      Sensory and motor nuclei for four cranial nerves
•      Nuclei that help control respiration
•      Nuclei and tracts linking the cerebellum with the brain stem, cerebrum and spinal cord
•      Ascending, descending and transverse tracts

The Cerebellum
The cerebellum
•      Adjusts postural muscles and tunes on-going movements
•      Cerebellar hemispheres
•    Anterior and posterior lobes
•    Vermis
•    Flocculonodular lobe
•      Superior, middle and inferior cerebellar peduncles link cerebellum with brain stem, diencephalon, cerebrum, and spinal cord
•    Interconnects the two cerebellar hemispheres

The Mesencephalon
The mesencephalon
•      The tectum (roof) contains the corpora quadrigemina
•     Superior and inferior colliculi
•      The mesencephalon contains many nuclei
•    Red nucleus
•    Substantia nigra
•    Cerebral peduncles
•    RAS headquarters

The Diencephalon
The diencephalon is composed of
•      Epithalamus
•      Hypothalamus
•      Thalamus

The thalamus
•      Final relay point for ascending sensory information
•      Coordinates the activities of the cerebral cortex and basal nuclei

The hypothalamus
•      Controls somatic motor activities at the subconscious level
•      Controls autonomic function
•      Coordinates activities of the endocrine and nervous systems
•      Secretes hormones
•      Produces emotions and behavioral drives
•      Coordinates voluntary and autonomic functions
•      Regulates body temperature
•      Coordinates circadian cycles of activity

The Limbic System
The limbic system or motivational system includes
•      Amygdaloid body
•      Cingulated gyrus
•      Parahippocampal gyrus
•      Hippocampus
•      Fornix
•      Functions of the limbic system involved emotions and behavioral drives

The Cerebrum
The cerebral cortex
•      Surface contains gyri and sulci or fissures
•    Longitudinal fissure separates two cerebral hemispheres
•    Central sulcus separates frontal and parietal lobes
•    Temporal and occipital lobes also bounded by sulci

White matter of the cerebrum
•      Contains association fibers
•      Commissural fibers
•      Projection fibers

The basal nuclei
•      Caudate nucleus
•      Globus pallidus
•      Putamen
•    Control muscle tone and coordinate learned movement patterns

Motor and sensory areas of the cortex
•      Primary motor cortex of the precentral gyrus directs voluntary movements
•      Primary sensory cortex of the postcentral gyrus receives somatic sensory information
•    Touch
•    Pressure
•    Pain
•    Taste
•    Temperature

Association areas
•      Control our ability to understand sensory information and coordinate a response
•    Somatic sensory association area
•    Visual association area
•    Somatic motor association area

general interpretive and speech areas
•      General interpretive area
•    Receives information from all sensory areas
•    Present only in left hemisphere
•      Speech center
•    Regulates patterns of breathing and vocalization

cortex functions and hemispheric differences
•      Prefrontal cortex
•    Coordinates information from secondary and special association areas
•    Performs abstract intellectual functions
•      Hemispheric differences
•    Left hemisphere typically contains general interpretive and speech centers and is responsible for language based skills
•    Right hemisphere is typically responsible for spatial relationships and analyses

Electroencephalogram (EEG)
•      Measures brain activity
•    Alpha waves = healthy resting adult
•    Beta waves = concentrating adult
•    Theta waves = normal children
•    Delta waves = normal during sleep

Focus: Cranial Nerves
•      12 pairs of cranial nerves
•    Each attaches to the ventrolateral surface of the brainstem near the associated sensory or motor nuclei

The Brain and Cranial Nerves
Olfactory nerves (I)
•      Carry sensory information responsible for the sense of smell
•      Synapse within the olfactory bulb

cranial nerves II, III, IV
•      Optic nerves (II)
•    Carry visual information from special sensory receptors in the eyes
•      Occulomotor nerves (III)
•    Primary source of innervation for 4 of the extraocular muscles
•      Trochlear nerves (IV)
•    Innervate the superior oblique muscles

cranial nerves V, VI, VII
•      Trigeminal nerves (V)
•    Missed nerves with ophthalmic, maxillary and mandibular branches
•      Abducens nerve (VI)
•    Innervates the lateral rectus muscles
•      Facial nerves (VII)
•    Mixed nerves that control muscles of the face and scalp
•    Provide pressure sensations over the face
•    Receive taste information from the tongue

cranial nerves VIII, IX
•      Vestibulocochlear nerves (VIII)
•    Vestibular branch monitors balance, position and movement
•    Cochlear branch monitors hearing
•      Glossopharyngeal nerves (IX)
•    Mixed nerves that innervate the tongue and pharynx
•    Control the action of swallowing

cranial nerves X
•      Vagus nerves (X)
•    Mixed nerves
•    Vital to the autonomic control of visceral function

cranial nerves XI, XII
•      Accessory nerves (XI)
•    Internal branches
•   Innervate voluntary swallowing muscles of the soft palate and pharynx
•    External branches
•   Control muscles associates with the pectoral girdle
•      Hypoglossal nerves (XII)
•    Provide voluntary motor control over tongue movement

Cranial Reflexes
Cranial reflexes
•      Involve sensory and motor fibers of cranial nerves
The Spinal Cord and Spinal Nerves

General Organization of the Nervous System
Divisions of the Nervous System
•      CNS
•    Brain and spinal cord
•    In the white matter, axons arranged in tracts and columns
•      PNS
•    Remainder of nervous tissue

Gross Anatomy of the Spinal Cord
Adult spinal cord
•      Localized enlargements provide innervation to limbs
•      31 segments
•    each segment has a pair of dorsal roots and a pair of ventral roots
•      Filum terminale
•      Conus medularis
•      Spinal nerves extend off cord
•    Mixed nerves

Spinal meninges
•      Provide physical stability and shock absorption
•      Three layers
•    Dura mater
•    Arachnoid
•    Pia mater

Dura mater
•      Covers spinal cord
•      Tapers to coccygeal ligament
•      Epidural space separates dura mater from walls of vertebral canal

Arachnoid
•      Interior to dura mater are the subdural space, the arachnoid and the subarachnoid space
•    Subarachnoid space contains CSF

Pia mater
•      Meshwork of elastin and collagen fibers
•      Innermost meningeal layer
•      Denticulate ligaments extend from pia mater to dura mater

Sectional anatomy of the spinal cord
•      White matter is myelinated and unmyelinated axons
•      Gray matter is cell bodies, unmyelinated axons and neuroglia
•    Projections of gray matter toward outer surface of cord are horns

Horns of spinal cord
•      Posterior gray horn contains somatic and visceral sensory nuclei
•      Anterior gray horns deal with somatic motor control
•      Lateral gray horns contain visceral motor neurons
•      Gray commissures contain axons that cross from one side to the other

White matter
•      Divided into six columns (funiculi) containing tracts
•      Ascending tracts relay information from the spinal cord to the brain
•      Descending tracts carry information from the brain to the spinal cord

Spinal Nerves
31 pairs of spinal nerves
•      Nerves consist of:
•    Epineurium
•    Perineurium
•    Endoneurium

Spinal nerves
•      White ramus (myelinated axons)
•      Gray ramus (unmyelinated axons that innervate glands and smooth muscle)
•      Dorsal ramus (sensory and motor innervation to the skin and muscles of the back)
•      Ventral ramus (supplying ventrolateral body surface, body wall and limbs)
•      Each pair of nerves monitors one dermatome

Nerve plexus
•      Complex interwoven network of nerves
•      Four large plexuses
•    Cervical plexus
•    Brachial plexus
•    Lumbar plexus
•    Sacral plexus



Principles of Functional Organization
General organization
•      Sensory neurons
•    Deliver information to CNS
•      Motor neurons
•    Distribute commands to peripheral effectors
•      Interneurons
•    Interpret information and coordinate responses

Neuronal pools
•      Functional group of interconnected neurons
•      Neural circuit patterns
•    Divergence
•    Convergence
•    Serial processing
•    Parallel processing
•    Reverberation

An introduction to reflexes
•      Reflexes are rapid automatic responses to stimuli
•      Neural reflex involves sensory fibers to CNS and motor fibers to effectors
Reflex arc
•      Wiring of a neural reflex
•      Five steps
•    Arrival of stimulus and activation of receptor
•    Activation of sensory neuron
•    Information processing
•    Activation of motor neuron
•    Response by effector

Reflex classification
•      According to
•    development
•   Site of information processing
•   Nature of resulting motor response
•   Complexity of neural circuit
•      Innate reflexes
•    Result from connections that form between neurons during development
•      Acquired reflexes
•    Learned, and typically more complex

More reflex classifications
•      Cranial reflexes
•    Reflexes processed in the brain
•      Spinal reflexes
•    Interconnections and processing events occur in the spinal cord
•      Somatic reflexes
•    Control skeletal muscle
•      Visceral reflexes (autonomic reflexes)
•    Control activities of other systems
•      Monosynaptic reflex
•    Sensory neuron synapses directly on a motor neuron
•      Polysynaptic reflex
•    At least one interneuron between sensory afferent and motor efferent
•    Longer delay between stimulus and response

Spinal Reflexes
Spinal Reflexes
•      Range from simple monosynaptic to complex polysynaptic and intersegmental
•    Many segments interact to form complex response

Monosynaptic Reflexes
•      Stretch reflex automatically monitors skeletal muscle length and tone
•    Patellar (knee jerk) reflex
•      Sensory receptors are muscle spindles
•      Postural reflex maintains upright position

Polysynaptic reflexes
•      Produce more complicated responses
•    Tendon reflex
•    Withdrawal reflexes
•    Flexor reflex
•    Crossed extensor reflex

Polysynaptic reflexes
•      Involve pools of interneurons
•      Are intersegmental in distribution
•      Involve reciprocal inhibition
•      Have reverberating circuits to prolong the motor response
•      Several reflexes may cooperate to produce a coordinated response

Integration and Control of Spinal Reflexes
Control of spinal reflexes
•      Brain can facilitate or inhibit motor patterns based in spinal cord
•      Motor control involves a series of interacting levels
•    Monosynaptic reflexes are the lowest level
•    Brain centers that modulate or build on motor patterns are the highest

Reinforcement and inhibition
•      Reinforcement = facilitation that enhances spinal reflexes
•      Spinal reflexes can also be inhibited
•    Babinski reflex replaced by planter reflex

Neural Integration : Sensory Pathways and the Somatic Nervous System

An Overview of Sensory Pathways and the Somatic Nervous System
Neural pathways
•      Afferent pathways
•    Sensory information coming from the sensory receptors through peripheral nerves to the spinal cord and on to the brain
•      Efferent pathways
•    Motor commands coming from the brain and spinal cord, through peripheral nerves to effecter organs

Sensory Receptors and their Classification
Sensory receptor
•      Specialized cell or cell process that monitors specific conditions
•      Arriving information is a sensation
•      Awareness of a sensation is a perception

Senses
•      General senses
•    Pain
•    Temperature
•    Physical distortion
•    Chemical detection
•   Receptors for general senses scattered throughout the body
•      Special senses
•    Located in specific sense organs
•    Structurally complex

Sensory receptors
•      Each receptor cell monitors a specific receptive field
•      Transduction
•    A large enough stimulus changes the receptor potential, reaching generator potential

Receptors
•      Tonic receptors
•    Always active
•    Slow acting receptors
•      Phasic receptors
•    Provide information about the intensity and rate of change of a stimulus
•    Fast acting receptors
•      Adaptation
•    Reduction in sensitivity in the presence of a constant stimulus

The general senses
•      Three types of nociceptor
•    Provide information on pain as related to extremes of temperature
•    Provide information on pain as related to extremes of mechanical damage
•    Provide information on pain as related to extremes of dissolved chemicals
•    Myelinated type A fibers carry fast pain
•    Slower type C fibers carry slow pain

Thermoceptors and mechaniceptors
•      Found in the dermis
•      Mechaniceptors
•    Sensitive to distortion of their membrane
•   Tactile receptors (six types)
•   Baroreceptors
•   Proprioceptors (three groups)

Chemoreceptors
•      Chemoreceptors
•    Carotid bodies
•    Aortic bodies



Neural Integration I: Sensory Pathways and the Somatic Nervous System

The Organization of Sensory Pathways
First, second, and third order neurons
•      First order neurons
•    Sensory neurons that deliver sensory information to the CNS
•      Second order neurons
•    First order neurons synapse on these in the brain or spinal cord
•      Third order neurons
•    Found in the thalamus
•    Second order neurons synapse on these

Somatic sensory pathways
•      Three major pathways carry sensory information
•    Posterior column pathway
•    Anterolateral pathway
•    Spinocerebellar pathway

Posterior column pathway
•      Carries fine touch, pressure and proprioceptive sensations
•      Axons ascend within the fasciculus gracilis and fasciculus cuneatus
•      Relay information to the thalamus via the medial lemniscus
•    Decussation

Anterolateral pathway
•      Carries poorly localized sensations of touch, pressure, pain, and temperature
•      Axons decussate in the spinal cord and ascend within  the anterior and lateral spinothalamic tracts
•      Headed toward the ventral nuclei of the thalamus

Spinocerebellar pathway
•      Includes the posterior and anterior spinocerebellar tracts
•      Carries sensation to the cerebellum concerning position of muscles, tendons and joints

Visceral sensory pathways
•      Carry information collected by interoceptors
•      Information from cranial nerves V, VII, IX and X delivered to solitary nucleus in medulla oblongata
•      Dorsal roots of spinal nerves T1 – L2 carry visceral sensory information from organs between the diaphragm and pelvis
•      Dorsal roots of spinal nerves S2 – S4 carry sensory information below this area

The Somatic Nervous System
Somatic motor pathways
•      Upper motor neuron
•    Cell body lies in a CNS processing center
•      Lower motor neuron
•    Cell body located in a motor nucleus of the brain or spinal cord

The corticospinal pathway
•      Provides voluntary skeletal muscle control
•      Corticobulbar tracts terminate at cranial nerve nuclei
•      Corticospinal tracts synapse on motor neurons in the anterior gray horns of the spinal cord
•    Visible along medulla as pyramids

Pyramids
•      Most of the axons decussate to enter the descending lateral corticospinal tracts
•      Those that do not cross over enter the anterior corticospinal tracts
•      Provide rapid direct method for controlling skeletal muscle

medial and lateral pathways
•      The medial and lateral pathways
•    Issue motor commands as a result of subconscious processing
•      Medial pathway
•    Primarily controls gross movements of the trunk and proximal limbs
•    Includes the vestibulospinal tracts, tectospinal tracts and reticulospinal tracts

lateral pathways
•      Lateral pathway
•    Controls muscle tone and movements of the distal muscles of the upper limbs
•    Rubrospinal tracts

The basal nuclei and cerebellum
•      Basal nuclei adjust motor commands issued in other processing centers
•      Provide background patterns of movement involved in voluntary motor movements
•      Cerebellum monitors proprioceptive information, visual information and vestibular sensations

control and responses
•      Levels of processing and motor control
•    Spinal and cranial reflexes provide rapid, involuntary, preprogrammed responses
•      Voluntary responses
•    More complex
•    Require more time to prepare and execute

During development
•      Spinal and cranial reflexes are first to appear
•      Complex reflexes develop as CNS matures and brain grows
The Autonomic Nervous System and Higher Order Functions

An Overview of the ANS
ANS
•      Coordinates cardiovascular, respiratory, digestive, urinary and reproductive functions
•      Preganglionic neurons in the CNS send axons to synapse on ganglionic neurons in autonomic ganglia outside the CNS

Divisions of the ANS
•      Sympathetic division (thoracolumbar, “fight or flight”)
•    Thoracic and lumbar segments
•      Parasympathetic division (craniosacral, “rest and repose”)
•    Preganglionic fibers leaving the brain and sacral segments

The Sympathetic Division
Sympathetic division anatomy
•      Preganglionic neurons between segments T1 and L2
•      Ganglionic neurons in ganglia near vertebral column
•      Specialized neurons in adrenal glands

Sympathetic ganglia
•      Sympathetic chain ganglia (paravertebral ganglia)
•      Collateral ganglia  (prevertebral ganglia)

Organization and anatomy of the sympathetic division
•      Segments T1-L2, ventral roots give rise to myelinated white ramus
•      Leads to sympathetic chain ganglia

Postganglionic fibers
•      Rejoin spinal nerves and reach their destination by way of the dorsal and ventral rami
•      Those targeting structures in the thoracic cavity form sympathetic nerves
•    Go directly to their destination

Abdominopelvic viscera
•      Sympathetic innervation via preganglionic fibers that synapse within collateral ganglia
•    Splanchic nerves

Abdominopelvic viscera
•      Celiac ganglion
•    Innervates stomach, liver, gall bladder, pancreas, spleen
•      Superior mesenteric ganglion
•    Innervates small intestine and initial portion of large intestine
•      Inferior mesenteric ganglion
•    Innervates kidney, urinary bladder, sex organs, and final portion of large intestine

Sympathetic activation
•      In crises, the entire sympathetic division responds
•    Sympathetic activation
•    Affects include increased alertness, energy and euphoria, increased cardiovascular and respiratory activities, elevation in muscle tone, mobilization of energy resources

Neurotransmitters and sympathetic function
•      Stimulation of sympathetic division has two distinct results
•    Release of ACh or NE at specific locations
•    Secretion of E and NE into general circulation
•      Most postganglionic fibers are adrenergic, a few are cholinergic or nitroxidergic
•      Two types of receptors are alpha receptors and beta receptors
•      Sympathetic ganglionic neurons end in telodendria studded with varicosities filled with neurotransmitter




The Parasympathetic Division
Parasympathetic division
•      Preganglionic neurons in the brainstem and sacral segments of spinal cord
•      Ganglionic neurons in peripheral ganglia located within or near target organs

Organization and anatomy of the parasympathetic division
•      Preganglionic fibers leave the brain as cranial nerves III, VI, IX, X
•      Sacral neurons form the pelvic nerves

Parasympathetic activation
•      Effects produced by the parasympathetic division
•    relaxation
•    food processing
•    energy absorption

Neurotransmitters and parasympathetic functions
•      All parasympathetic fibers release ACh
•      Short-lived response as ACH is broken down by AChE and tissue cholinesterase
•      Postsynaptic membranes have two kinds of receptors
•    Muscarinic
•    Nicotinic

Interactions Between the Sympathetic and Parasympathetic Divisions
Sympathetic and parasympathetic divisions
•      Sympathetic
•    Widespread influence on visceral and somatic structures
•      Parasympathetic
•    Innervates only visceral structures serviced by cranial nerves or lying within the abdominopelvic cavity
•      Dual innervation = organs that receive input from both systems

Anatomy of dual innervation
•      Sympathetic and parasympathetic systems intermingle to form autonomic plexuses
•    Cardiac plexus
•    Pulmonary plexus
•    Esophageal plexus
•    Celiac plexus
•    Inferior mesenteric plexus
•    Hypogastric plexus

Comparison of the two divisions
•      Important physiological and functional differences exist
Figure 16.10  Summary: The Anatomical Differences between the Sympathetic and Parasympathetic Divisions

Integration and Control of Autonomic Functions
Visceral reflexes
•      Visceral reflex arcs are the simplest function of the ANS
•     Long reflexes (interneurons)
•     Short reflexes (bypassing CNS)
•      Parasympathetic reflexes govern respiration, cardiovascular function and other visceral activities

Higher levels of autonomic control
•      Activity in the ANS is controlled by centers in the brainstem that deal with visceral functioning

SNS and ANS organized in parallel
•      Integration occurs at the brainstem and higher centers


High Order Functions
Higher order functions
•      Are performed by the cerebral cortex and involve complex interactions
•      Involve conscious and unconscious information processing
•      Are subject to modification and adjustment over time

Memory
•      Short term or long term
•      Memory consolidation is moving from short term to long term
•      Amnesia is the loss of memory due to disease or trauma

Consciousness
•      Deep sleep, the body relaxes and cerebral cortex activity is low
•      REM sleep active dreaming occurs
•      The reticular activating system (RAS) is important to arousal and maintenance of consciousness

Brain Chemistry and Behavior
Neurotransmitters and the brain
•      Neurotransmitters and brain function
•    Changes in balance between neurotransmitters can profoundly alter brain function
•      Personality and self-awareness
•    Characteristics of the brain as an integrated system rather than one specific component

Aging and the Nervous System
Age-related changes
•      Reduction in brain size and weight
•      Reduction in the number of neurons
•      Decrease in blood flow to the brain
•      Changes in synaptic organization of the brain
•      Intracellular and extracellular changes in CNS neurons
The Special Senses

Olfaction
Olfactory organs
•      Contain olfactory epithelium with olfactory receptors, supporting cells, basal cells
•    Olfactory receptors are modified neurons
•      Surfaces are coated with secretions from olfactory glands
•      Olfactory reception involved detecting dissolved chemicals as they interact with odorant binding proteins

Olfaction
•      Olfactory pathways
•    No synapse in the thalamus for arriving information
•      Olfactory discrimination
•    Can distinguish thousands of chemical stimuli
•   CNS interprets smells by pattern of receptor activity
•    Olfactory receptor population shows considerable turnover
•    Number of receptors declines with age

Gustation
Taste receptors
•      Clustered in taste buds
•      Associated with lingual papillae

Taste buds
•      Contain basal cells which appear to be stem cells
•      Gustatory cells extend taste hairs through a narrow taste pore

Gustatory pathways
•      Taste buds are monitored by cranial nerves
•    Synapse within the solitary nucleus of the medulla oblongata
•    Then on to the thalamus and the primary sensory cortex

Gustatory discrimination
•      Primary taste sensations
•    Sweet, sour, salty, bitter
•    Receptors also exist for umami and water
•      Taste sensitivity shows significant individual differences, some of which are inherited
•      The number of taste buds declines with age

Vision
Accessory structures of the eye
•      Eyelids (palpebrae) separated by the palpebral fissue
•      Eyelashes
•      Tarsal glands
•      Lacrimal apparatus

external structures of the eye
•      Conjunctiva covers most of eye
•      Cornea is transparent anterior portion

Lacrimal apparatus
•      Secretions from the lacrimal gland contain lysozyme
•      Tears form in the lacrimal glands, wash across the eye and collect in the lacrimal lake
•      Pass through the lacrimal punctae, lacrimal canaliculi, lacrimal sac and nasolacrimal duct

The eye
•      Three layers
•    Outer fibrous tunic
•   Sclera, cornea, limbus
•    Middle vascular tunic
•   Iris, ciliary body, choroid
•    Inner nervous tunic
•   Retina

internal structures of the eye
•      Ciliary body
•    Ciliary muscles and ciliary processes, which attach to suspensory ligaments of lens
•      Retina
•    Outer pigmented portion
•    Inner neural part
•   Rods and cones


The Special Senses
retina
•      Retina contains rods and cones
•    Cones densely packed at fovea (center of the macula lutea)
•      Retinal pathway
•    Photoreceptors to bipolar cells to ganglion cells, to the brain via the optic nerve
•   Axons of ganglion cells converge at blind spot (optic disc)
•    Horizontal cells and amacrine cells modify the signal passed along the retinal neurons

Eye anatomy
•      Ciliary body and lens divide the anterior cavity of the eye into posterior (vitreous) cavity and anterior cavity
•      Anterior cavity further divided
•    anterior chamber in front of eye
•    posterior chamber between the iris and the lens

Fluids in the eye
•      Aqueous humor circulates within the eye
•    diffuses through the walls of anterior chamber
•    passes through canal of Schlemm
•    re-enters circulation
•      Vitreous humor fills the posterior cavity.
•    Not recycled – permanent fluid

Lens
•      Posterior to the cornea and forms anterior boundary of posterior cavity
•    Posterior cavity contains vitreous humor
•      Lens helps focus
•    Light is refracted as it passes through lens
•    Accommodation is the process by which the lens adjusts to focus images
•    Normal visual acuity is 20/20

Visual physiology
•      Rods – respond to almost any photon
•      Cones – specific ranges of specificity

Photoreceptor structure
•      Outer segment with membranous discs
•      Narrow stalk connecting outer segment to inner segment
•      Light absorption occurs in the visual pigments
•    Derivatives of rhodopsin

Color sensitivity
•      Integration of information from red, blue and green cones
•      Colorblindness is the inability to detect certain colors

retinal adaptation
•      Dark adapted – most visual pigments are fully receptive to stimulation
•      Light adapted – pupil constricts and pigments bleached.

the visual pathway
•      Large M-cells monitor rods
•      Smaller more numerous P cells monitor cones

Seeing in stereo
•      Vision from the field of view transfers from one side to the other while in transit
•      Depth perception is obtained by comparing relative positions of objects from the two eyes

Visual circadian rhythm
•      Input to suprachiasmic nucleus affects the function of the brainstem
•      Circadian rhythm ties to day-night cycle, and affects metabolic rates

Equilibrium and Hearing
Both equilibrium and hearing are provided by receptors of the inner ear
Anatomy of the ear – External Ear
•    Auricle or pinnae surrounds the ear
•    External acoustic meatus ends on tympanic membrane

Middle ear
•      Communicates with pharynx via pharyngotympanic membrane
•      Middle ear encloses and protects the auditory ossicles

Inner ear
•      Membranous labyrinth contains endolymph
•      Bony labyrinth surrounds and protects membranous labyrinth
•    Vestibule
•    Semicircular canals
•    Cochlea

Components of the inner ear
•      Vestibule contains the utricle and saccule
•      Semicircular canals contain the semicircular ducts
•      Cochlea contains the cochlear duct

Windows
•      Round window separates the perilymph from the air spaces of the middle ear
•      Oval window connected to the base of the stapes
•      Basic receptors of inner ear are hair cells
•    Provide information about the direction and strength of stimuli

Equilibrium
•      Anterior, posterior and lateral semicircular ducts are continuous with the utricle
•    Each duct contains an ampulla with a gelatinous cupula and associated sensory receptor
•      Saccule and utricle connected by a passageway continuous with the endolymphatic duct
•    Terminates in the endolymphatic sac
•    Saccule and utricle have hair cells clustered in maculae
•    Cilia contact the otolith (statoconia)

Vestibular neural pathway
•      Vestibular receptors activate sensory neurons of the vestibular ganglia
•      Axons form the vestibular branch of cranial nerve VII
•      Synapses within the vestibular nuclei

Hearing
•      Cochlear duct lies between the vestibular duct and the tympanic duct
•      Hair cells of the cochlear duct lie within the Organ of Corti
•      Intensity is the energy content of a sound
•    Measured in decibels

Pathway of sound
•      Sound waves travel toward tympanic membrane, which vibrates
•      Auditory ossicles conduct the vibration into the inner ear
•    Tensor tympani and stapedius muscles contract to reduce the amount of movement when loud sounds arrive
•      Movement at the oval window applies pressure to the perilymph of the cochlear duct
•      Pressure waves distort basilar membrane
•      Hair cells of the Organ of Corti are pushed against the tectoral membrane

Neural pathway
•      Sensory neurons of hearing are located in the spiral ganglion of the cochlea
•      Afferent fibers form the cochlear branch of cranial nerve VIII
•    Synapse at the cochlear nucleus
The Endocrine System

Intercellular Communication
Endocrine versus Nervous system
•      Nervous system performs short term crisis management
•      Endocrine system regulates long term ongoing metabolic
•      Endocrine communication is carried out by endocrine cells releasing hormones
•    Alter metabolic activities of tissues and organs
•    Target cells
•      Paracrine communication involves chemical messengers between cells within one tissue

An Overview of the Endocrine System
Endocrine system
•      Includes all cells and endocrine tissues that produce hormones or paracrine factors

Hormone structure
•      Amino acid derivatives
•    Structurally similar to amino acids
•      Peptide hormones
•    Chains of amino acids
•      Lipid derivatives
•    Steroid hormones and eicosanoids

Hormones can be
•      Freely circulating
•    Rapidly removed from bloodstream
•      Bound to transport proteins

Mechanisms of hormone action
•      Receptors for catecholamines, peptide hormones, eicosanoids are in the cell membranes of target cells
•      Thyroid and steroid hormones cross the membrane and bind to receptors in the cytoplasm or nucleus

Control of endocrine activity
•      Endocrine reflexes are the counterparts of neural reflexes
•      Hypothalamus regulates the activity of the nervous and endocrine systems
•    Secreting regulatory hormones that control the anterior pituitary gland
•    Releasing hormones at the posterior pituitary gland
•    Exerts direct neural control over the endocrine cells of the adrenal medullae
Endocrine System

The Pituitary Gland
Hypophysis
•      Releases nine important peptide hormones
•      All nine bind to membrane receptors and use cyclic AMP as a second messenger

Gland
The anterior lobe (adenohypophysis)
•      Subdivided into the pars distalis, pars intermedia and pars tuberalis
•      At the median eminence, neurons release regulatory factors through fenestrated capillaries
•    Releasing hormones
•    Inhibiting hormones


The Endocrine System
Hypophyseal portal system
•      All blood entering the portal system will reach the intended target cells before returning to the general circulation

Hormones of the adenohypophysis
•      Thyroid stimulating hormone (TSH)
•    Triggers the release of thyroid hormones
•    Thyrotropin releasing hormone promotes the release of TSH
•      Adrenocorticotropic hormone (ACTH)
•    Stimulates the release of glucocorticoids by the adrenal gland
•    Corticotrophin releasing hormone causes the secretion of ACTH

Hormones of the adenohypophysis
•      Follicle stimulating hormone (FSH)
•    Stimulates follicle development and estrogen secretion in females and sperm production in males
•      Leutinizing hormone (LH)
•    Causes ovulation and progestin production in females and androgen production in males
•      Gonadotropin releasing hormone (GNRH) promotes the secretion of FSH and LH

Hormones of the adenohypophysis
•      Prolactin (PH)
•    Stimulates the development of mammary glands and milk production
•      Growth hormone (GH or somatotropin)
•    Stimulates cell growth and replication through release of somatomedins or IGF
•   Growth-hormone releasing hormone
(GH-RH)
•   Growth-hormone inhibiting hormone
(GH-IH)

Melanocyte stimulating hormone (MSH)
•      May be secreted by the pars intermedia during fetal development, early childhood, pregnancy or certain diseases
•      Stimulates melanocytes to produce melanin

The posterior lobe of the pituitary gland (neurohypophysis)
•      Contains axons of hypothalamic nerves
•      neurons of the supraoptic nucleus manufacture antidiuretic hormone (ADH)
•    Decreases the amount of water lost at the kidneys
•    Elevates blood pressure

The posterior lobe of the pituitary gland (neurohypophysis)
•      Neurons of the paraventricular nucleus manufacture oxytocin
•    Stimulates contractile cells in mammary glands
•    Stimulates smooth muscle cells in uterus

The Thyroid Gland
The thyroid
•      Lies near the thyroid cartilage of the larynx
•      Two lobes connected by an isthmus

Thyroid follicles and thyroid hormones
•      Thyroid gland contains numerous follicles
•    Release several hormones such as thyroxine (T4) and triiodothyronine (T3)
•      Thyroid hormones end up attached to thyroid binding globulins (TBG)
•    Some are attached to transthyretin or albumin

Thyroid hormones
•      Held in storage
•      Bound to mitochondria, thereby increasing ATP production
•      Bound to receptors activating genes that control energy utilization
•      Exert a calorigenic effect

Cells of the thyroid gland
•      C cells produce calcitonin
•    Helps regulate calcium concentration in body fluids

The Parathyroid Glands
Four parathyroid glands
•      Embedded in the posterior surface of the thyroid gland
•      Chief cells produce parathyroid hormone (PTH) in response to lower than normal calcium concentrations
•      Parathyroid hormones plus calcitriol are primary regulators of calcium levels in healthy adults




The Adrenal Glands
Adrenal cortex
•      Manufactures steroid hormones (corticosteroids)
•      Cortex divided into three layers
•    Zona glomerulosa (produces mineralocorticoids)
•    Zona fasciculate (produces glucocorticoids)
•    Zona reticularis (produces androgens)

Adrenal medulla
•      Produces epinephrine (~75 - 80%)
•      Produces norepinephrine (~25-30%)

The Pineal Gland
Pineal gland
•      Contains pinealocytes
•      Synthesize melatonin
•      Suggested functions include inhibiting reproductive function, protecting against damage by free radicals, setting circadian rhythms

The Pancreas
The pancreatic islets
•      Clusters of endocrine cells within the pancreas called Islets of Langerhans or pancreatic islets
•    Alpha cells secrete glucagons
•    Beta cells secrete insulin
•    Delta cells secrete GH-IH
•    F cells secrete pancreatic polypeptide

Insulin and glucagon
•      Insulin lowers blood glucose by increasing the rate of glucose uptake and utilization
•      Glucagon raises blood glucose by increasing the rates of glycogen breakdown and glucose manufacture by the liver

The Endocrine Tissues of Other Systems
The intestines
•      Produce hormones important to the coordination of digestive activities

The kidneys
•      Produce calcitriol and erythropoietin (EPO) and the enzyme rennin
•    Calcitriol = stimulates calcium and phosphate ion absorption along the digestive tract
•    EPO stimulates red blood cell production by bone marrow
•    Renin converts angiotensinogen to angiotensin I

Angiotensin I converted to angiotensin II in the lungs
•      Stimulates adrenal production of aldosterone
•      Stimulates pituitary gland release of ADH
•      Promotes thirst
•      Elevates blood pressure

The heart
•      Specialized muscle cells produce natriuretic peptides when blood pressure becomes excessive
•    Generally oppose actions of angiotensin II

The thymus
•      Produces thymosins
•    Help develop and maintain normal immune defenses

The gonads
•      Interstitial cells of the testes produce testosterone
•    Most important sex hormone in males
•      In females, oocytes develop in follicles
•    Follicle cells produce estrogens
•      After ovulation, the follicle cells form a corpus luteum that releases a mixture of estrogens and progesterone

Adipose tissues secrete
•      Leptin, a feedback control for appetite
•      Resistin, which reduces insulin sensitivity

Patterns of Hormonal Interaction
Hormones often interact, producing
•      Antagonistic (opposing) effects
•      Synergistic (additive) effects
•      Permissive effects (one hormone is required for the other to produce its effect)
•      Integrative effects (hormones produce different but complimentary results)

Hormones and growth
•      Normal growth requires the interaction of several endocrine organs
•      Six hormones are important
•    GH
•    Thyroid hormones
•    Insulin
•    PTH
•    Calcitriol
•    Reproductive hormones

Hormones and stress
•      Stress = any condition that threatens homeostasis
•      GAS (General Adaptation Syndrome) is our bodies response to stress-causing factors
•      Three phases to GAS
•    Alarm phase (immediate, fight or flight, directed by the sympathetic nervous system)
•    Resistance phase (dominated by glucocorticoids)
•    Exhaustion phase (breakdown of homeostatic regulation and failure of one or more organ systems)

Hormones and behavior
•      Many hormones affect the CNS
•      Changes in the normal mixture of hormones significantly alters intellectual capabilities, memory, learning and emotional states

Aging and Hormone Production
Endocrine system
•      Few functional changes with age
•    Chief change is a decline in concentration of reproductive hormones
Osseous Tissue and Skeletal Structure


The Skeletal System: An Introduction
The skeletal system includes
•      Bones of the skeleton
•      Cartilages, ligaments and other connective tissues that stabilize and connect

Functions of the skeletal system
•      Support
•      Storage of minerals and lipids
•      Blood cell production
•      Protection
•      Leverage

A Classification of Bones
Bone shapes
•      Long
•      Flat
•      Short
•      Irregular
•      Sesamoid
•      Sutural

Bone structure = two types of bone
•      Compact bone (dense)
•      Spongy bone (cancellous)

A typical long bone includes
•      Diaphysis
•      Epiphyses
•      Metaphysis
•      Articular cartilage
•      Marrow cavity
•    Filled with red or yellow marrow

Bone Histology
Osseous tissue
•      Supporting tissue with a solid matrix
•    Crystals of hydroxyapatite
•      Minerals deposited in lamellae
•      Covered by periosteum

Cells in bone:
•      Osteocytes = mature bone cells
•    In lacunae
•    Connected by canaliculi
•      Osteoblasts synthesize new matrix
•    Osteogenesis
•      Osteoclasts dissolve bone matrix
•    Osteolysis
•      Osteoprogenitor cells differentiate into osteoblasts

Compact bone and spongy bone
•      Basic unit of compact bone is an osteon
•    Osteocytes arranged around a central canal
•    Perforating canals extend between adjacent osteons
•      Spongy bone contains trabeculae

Bones and stress
•      Compact bone located where stresses are limited in direction
•      Spongy bone located where stresses are weaker or multi-directional

Bones are:
•      Covered by periosteum
•      Lined by endosteum

Bone development and growth
•      Ossification = converting other tissue to bone
•      Calcification = depositing calcium salts within tissues

Osseous Tissue and Skeletal Structure
Intramembranous ossification
•      Begins with osteoblast differentiation
•      Dermal bones produced
•      Begins at ossification center

Figure 6.7  Intramembranous Ossification
Endochondral ossification
•      Cartilage model gradually replaced by bone at metaphysis
•    Increasing bone length
•      Timing of epiphyseal closure differs
•      Appositional growth increases bone diameter

Osseous Tissue and Skeletal Structure

The Dynamic Nature of Bone
continually changing
•      Remodeling
•      Exercise
•      Hormone levels
•    Growth hormone and thyroxine increase bone mass
•    Calcitonin and PTH control blood calcium levels

The skeleton is a calcium reserve
•      99% body’s calcium in the skeleton
•      Calcium ion concentration maintained by bones GI tract and kidneys
•      Calcitonin and PTH regulate blood calcium levels
•    Calcitonin decreases blood calcium levels
•    PTH increases blood calcium levels

Fracture repair
•      Fracture hematoma
•      External callus

Internal callus


Bone Markings (Surface Features)
Bone markings
•      Are characteristic for each bone and each individual
•      Markings include
•    Elevations
•    Projections
•    Depressions
•    Grooves and tunnels

Aging and the Skeletal System
Effects of aging include
•      Osteopenia
•      Osteoporosis


The Appendicular Skeleton


The Pectoral Girdle and Upper Limbs
The Appendicular Skeleton
•         Upper and lower limbs
•         Pectoral and pelvic girdle

Pectoral girdle (shoulder girdle)
•      Articulates the upper limbs with the trunk
•      Consists of clavicle and scapula

Clavicle and scapula
•      Position the shoulder joint
•      Help move the upper limb
•      Provide a base for muscle attachment

Scapula markings are attachment sites for tendons/ligaments of shoulder joint

The upper limbs
•      Scapula articulates with the humerus at the glenohumoral joint
•      Greater and lesser tubercles are muscle attachment sites

Humerus

Carpal bones and hand
•      Carpus forms wrist
•      Two rows of short bones
•      Distal row articulates with metacarpals
•      Four fingers have three phalanges
•    Pollex (thumb) has two




The pelvic girdle and lower limbs
•      More massive than the pectoral girdle
•      Consists of two os coxae
•    Fusion of ilium, ischium and pubis

Ilium
•      Largest hip bone
•      Within acetabulum, fused to the ischium (posteriorly) and the pubis (anteriorly)
•      Pubic symphysis limits left to right

Pelvis
•      Composed of the hipbones, sacrum and coccyx
•      Subdivided into the false (greater) and true (lesser) pelvis

The lower limbs
•      Femur is the longest bone in the body
•    Articulates with the tibia at the knee
•      Patella is a large sesamoid bone
•      Fibula parallels tibia laterally

Tarsus
•      Has seven tarsal bones
•      Pattern of metatarsal bones and phalanges parallels that of the hand
•    All toes have three phalanges except the hallux (two phalanges)

Ankle and arches
•      When standing, most of the weight of the body is transferred from the talus to the calcaneous
•    Rest is passed on to metatarsals
•      Weight transfer occurs along longitudinal arch
•    Transverse arch

Individual Variation in the Skeletal System
Important Variation in the Skeletal System
•      Medical history
•      Weight
•      Gender
•      Body size
•      Muscle mass
•      Age

Age related changes in skeletal system
•      Begin about age one
•      Continue throughout life


The Axial Skeleton


Skeletal system includes both:
•      Axial skeleton
•    Skull
•    Auditory ossicles and hyoid bone
•    Vertebral column
•    Thoracic cage
•      Appendicular skeleton
•    Pectoral and pelvic girdles
•    Upper and lower limbs

The skull
•      Consists of the cranium and the bones of the face
•    The cranium encloses cranial cavity
•    Facial bones surround and protect the entrances to the respiratory and digestive tracts
•      Superficial landmarks include the sutures
•    Lambdoid
•    Coronal
•    Sagittal
•    Squamous

Focus: The Individual Bones of the Skull Cranial Bones
•      one occipital bone
•    foramen magnum
•      two parietal bones
•      one frontal bone
•    frontal sinuses

The Axial Skeleton


Facial bones
•      Maxillary bones
•      Mandible
•      Palatine bones
•      Nasal bones
•      Vomer

Maxillae
•      Largest facial bones
•      Form the upper jaw and most of the hard palate

Palatine and Nasal Bones
•      Palatine bones
•    Small “L” shaped bones
•    Form the posterior hard palate and floor of the nasal cavity
•      Nasal bones
•    Superior border of external nares

Vomer, Zygomatic and Lacrimal bones
•      Vomer
•    Inferior portion of the nasal septum
•      Zygomatic bone
•    Temporal process articulates with zygomatic process of temporal bone
•      Lacrimal bones
•    Smallest bones of the face
•    Sit medially in orbit

Mandible and Hyoid bones
•      Mandible
•    Bone of the lower jaw
•      Hyoid
•    Suspended by stylohyoid ligaments
•    Supports the larynx

The orbital and nasal complexes
•      Seven bones in the orbital complex
•      Nasal complex = bones that enclose the nasal cavities and paranasal sinuses

Skulls of infants and children
•      Fontanels permit skulls of infants and children to continue growing


Vertebral column
•      Vertebrae, sacrum, coccyx
•    7 cervical vertebrae
•    12 thoracic vertebrae
•    5 lumbar vertebrae
•    Sacrum and coccyx are fused vertebrae

Spinal curvature
•      Four spinal curves
•    Primary (accommodation) curves = thoracic and sacral
•    Secondary (compensation) curves = lumbar and cervical

Vertebral anatomy
•      Typically has a body and vertebral arch
•      Superior and inferior articular processes
•      Separated by intervertebral discs

Vertebral regions
•      Cervical
•    Has distinctive shape
•    Large relative size of vertebral foramen
•    Costal processes with transverse foramina
•    Notched spinous processes

Thoracic vertebrae
•      Heart-shaped body
•      Long slender spinous processes
•      Articulations for ribs


Lumbar vertebrae
•      Most massive
•      Least mobile
•      Subjected to great stresses

Sacrum
•      Protects reproductive, digestive and urinary organs
•      Articulates with pelvic girdle and fused elements of coccyx

Thoracic cage
•      Thoracic vertebrae
•      Ribs
•      Sternum
•    Ribs and sternum forms the rib cage

The ribs
•      Ribs 1-7 are attached to vertebrae
•      8-12 are vertebrochondral ribs
•      11-12 are floating ribs

Typical rib
•      Has a head, neck, tubercle and a body
•      Costal groove marks pathway of blood returning to the heart

The Sternum consists of
•      Manubrium
•      Body
•      Xiphoid process



Articulations


A Classification of Joints
Articulations
•      Articulations
•    Where two bones interconnect
•      Immovable joints
•    Synarthroses, or bony
•      Slightly moveable joints
•    Amphiarthroses, or fibrous / cartilagenous
•      Freely moveable joints
•    Diarthroses, or synovial

Synarthroses (immovable joints)
•      Four major types
•    Suture = skull bones bound together by dense connective tissue
•    Gomphosis = teeth bound to bony sockets by periodontal ligaments
•    Synchondrosis = two bones bound by rigid cartilaginous bridge
•    Syntosis = two bones completely fused

Amphiarthroses (slightly movable joints)
•      Two major types
•    Syndesmosis = bones connected by a ligament
•    Symphysis = bone separated by fibrocartilage

Diarthroses (freely movable joints)
•      Bony surfaces enclosed within articular capsule
•      Bony surfaces covered by articular cartilage
•      Bony surfaces lubricated by synovial fluid
•      Structures include
•    Menisci
•    Fat pads
•    Accessory ligaments
•    Bursae

Articular Form and Function
Dynamic motion
•      Dynamic motion
•    Linear motion
•    Angular motion
•    Rotation
•      Joints classified based on type of motion permitted
•    Monaxial
•    Biaxial
•    Triaxial


Types of movement
•      Gliding motion
•    Two surfaces slide past one another
•      Angular motion
•    Flexion, extension, hyperextension
•    Abduction, adduction
•    Circumduction


Rotational movement
•      Left or right
•      Medial (internal) or lateral (external)
•      Pronation or supination in the bones of the forearm only


Special movement
•      Movements of the foot
•    Inversion and eversion
•    Plantar flexion and dorsiflexion
•      Movements of the thumb
•    Opposition

Other movements
•      Protraction moves a structure anteriorly
•      Retraction moves a structure posteriorly
•      Elevation moves a structure superiorly
•      Depression moves a structure inferiorly
•      Lateral flexion bends the vertebrae to one side

Structural classification of joints
•      Gliding joints permit movement in a single plane
•      Hinge joints are monaxial joints permitting angular motion in one plane
•      Pivot joints are monaxial joints that permit rotation
•      Ellipsoid joints are biaxial joints that pit one bone in an oval depression of another
•      Saddle joints are biaxial joints with one concave and one convex bone face
•      Ball-and-socket joints are triaxial joints that permit rotation and other movements

Representative Articulations
Intervertebral articulations
•      Gliding joints
•      Vertebral bodies form symphyseal joints cushioned by intervertebral discs
•    Outer anulus fibrosus and inner nucleus pulposus
•      Stabilized by ligaments

Shoulder joint (glenohumoral joint)
•      Glenoid cavity and head of humerus
•      Ball and socket diarthroses
•      Stabilized by ligaments
•      Strength and stability sacrificed for range of motion

The elbow joint
•      Permits only flexion and extension
•      Hinge diarthroses
•      Reinforced with strong ligaments

Hip joint
•      Ball and socket diarthroses
•      Acetabulum and head of femur
•      Permits flexion/extension, abduction/ adduction, circumduction, rotation
•      Stabilized by numerous ligaments

Knee joint
•      Hinge joint with incomplete articular capsule
•      Formed by the condyles of the femur and the condylar surfaces of the tibia
•      Accessory structures help stabilize lateral movements
•      Permits flexion/extension, limited rotation
•      Supported by ligaments

Aging and Articulations
Joint problems with aging
•      Joint problems associated with aging
•    Relatively common
•    Rheumatism – general term for pain and stiffness in muscular and skeletal elements
•    Arthritis – all rheumatic diseases affecting synovial joints

Bones and Muscles
Musculoskeletal system
•      Encompasses the extensive interactions between the muscular and skeletal systems
Muscle Tissue


Skeletal muscle tissue and the Muscular System
Three types of muscle
•      Skeletal – attached to bone
•      Cardiac – found in the heart
•      Smooth – lines hollow organs

Skeletal muscle functions
•      Produce skeletal movement
•      Maintain posture and body position
•      Support soft tissues
•      Guard entrances and exits
•      Maintain body temperature

Anatomy of Skeletal Muscle
Organization of connective tissues
•      Epimysium surrounds muscle
•      Perimysium sheathes bundles of muscle fibers
•    Epimysium and perimysium contain blood vessels and nerves
•      Endomysium covers individual muscle fibers
•      Tendons or aponeuroses attach muscle to bone or muscle

Skeletal muscle fibers
•      Sarcolemma (cell membrane)
•      Sarcoplasm (muscle cell cytoplasm)
•      Sarcoplasmic reticulum (modified ER)
•      T-tubules and myofibrils aid in contraction
•      Sarcomeres – regular arrangement of myofibrils

Myofibrils
•      Thick and thin filaments
•      Organized regularly

Muscle Fiber
Thin filaments
•      F-actin
•      Nebulin
•      Tropomyosin
•    Covers active sites on G-actin
•      Troponin
•    Binds to G-actin and holds tropomyosin in place

Thick filaments
•      Bundles of myosin fibers around titan core
•    Myosin molecules have elongate tail, globular head
•    Heads form cross-bridges during contraction
•    Interactions between G-actin and myosin prevented by tropomyosin during rest

Sliding filament theory
•      Explains the relationship between thick and thin filaments as contraction proceeds
•      Cyclic process beginning with calcium release from SR
•    Calcium binds to troponin
•    Trponin moves, moving tropomyosin and exposing actin active site
•    Myosin head forms cross bridge and bends toward H zone
•    ATP allows release of cross bridge


The Contraction of Skeletal Muscle
Tension
•      Created when muscles contract
•      Series of steps that begin with excitation at the neuromuscular junction
•    Calcium release
•    Thick/thin filament interaction
•    Muscle fiber contraction
•    Tension

Control of skeletal muscle activity occurs at the neuromuscular junction
•      Action potential arrives at synaptic terminal
•      ACh released into synaptic cleft
•      ACh binds to receptors on post-synaptic neuron
•    Action potential in sarcolemma

Excitation/contraction coupling
•      Action potential along T-tubule causes release of calcium from cisternae of SR
•      Initiates contraction cycle
•   Attachment
•   Pivot
•   Detachment
•   Return

Relaxation
•      Acetylcholinesterase breaks down ACh
•      Limits the duration of contraction

Tension Production
Tension production by muscle fibers
•      All or none principle
•      Amount of tension depends on number of cross bridges formed
•      Skeletal muscle contracts most forcefully over a narrow ranges of resting lengths
•      Twitch
•    Cycle of contraction, relaxation produced by a single stimulus
•      Treppe
•    Repeated stimulation after relaxation phase has been completed

Summation
•      Repeated stimulation before relaxation phase has been completed
•    Wave summation = one twitch is added to another
•    Incomplete tetanus = muscle never relaxes completely
•    Complete tetanus = relaxation phase is eleminated

Tension production by skeletal muscles
•      Internal tension generated inside contracting muscle fibers
•      External tension generated in extracellular fibers
•      Motor units
•    All the muscle fibers innervated by one neuron
•    Precise control of movement determined by number and size of motor unit
•      Muscle tone
•    Stabilizes bones and joints


Tension production by skeletal muscles
•      Internal tension generated inside contracting muscle fibers
•      External tension generated in extracellular fibers
•      Motor units
•    All the muscle fibers innervated by one neuron
•    Precise control of movement determined by number and size of motor unit
•      Muscle tone
•    Stabilizes bones and joints

Contractions
•      Isometric
•    Tension rises, length of muscle remains constant
•      Isotonic
•   Tension rises, length of muscle changes
•      Resistance and speed of contraction inversely related
•      Return to resting lengths due to elastic components, contraction of opposing muscle groups, gravity

Energy Use and Muscle Contraction
Muscle Contraction requires large amounts of energy
•      Creatine phosphate releases stored energy to convert ADP to ATP
•      Aerobic metabolism provides most ATP needed for contraction
•      At peak activity, anaerobic glycolysis needed to generate ATP

Energy use and level of muscular activity
•      Energy production and use patterns mirror muscle activity
•      Fatigued muscle no longer contracts
•    Build up of lactic acid
•    Exhaustion of energy resources

Recovery period
•      Begins immediately after activity ends
•      Oxygen debt (excess post-exercise oxygen consumption)
•    Amount of oxygen required during resting period to restore muscle to normal conditions

Muscle Performance
Types of skeletal muscle fibers
•      Fast fibers
•      Slow fibers
•      Intermediate fibers

Fast fibers
•      Large in diameter
•      Contain densely packed myofibrils
•      Large glycogen reserves
•      Relatively few mitochondria
•      Produce rapid, powerful contractions of short duration

Slow fibers
•      Half the diameter of fast fibers
•      Take three times as long to contract after stimulation
•      Abundant mitochondria
•      Extensive capillary supply
•      High concentrations of myoglobin
•      Can contract for long periods of time

Intermediate fibers
•      Similar to fast fibers
•      Greater resistance to fatigue

Muscle performance and the distribution of muscle fibers
•      Pale muscles dominated by fast fibers are called white muscles
•      Dark muscles dominated by slow fibers and myoglobin are called red muscles
•      Training can lead to hypertrophy of stimulated muscle

Physical conditioning
•      Anaerobic endurance
•    Time over which muscular contractions are sustained by glycolysis and ATP/CP reserves
•      Aerobic endurance
•    Time over which muscle can continue to contract while supported by mitochondrial activities

Cardiac Muscle Tissue
Structural characteristics of cardiac muscle
•      Located only in heart
•      Cardiac muscle cells are small
•    One centrally located nucleus
•    Short broad T-tubules
•    Dependent on aerobic metabolism
•      Intercalated discs where membranes contact one another

Functional characteristics of cardiac muscle tissue
•      Automaticity
•      Contractions last longer than skeletal muscle
•      Do not exhibit wave summation
•    No tetanic contractions possible

Smooth Muscle Tissue
Structural characteristics of smooth muscle
•      Nonstriated
•    Lack sarcomeres
•    Thin filaments anchored to dense bodies
•      Involuntary

Functional characteristics of smooth muscle
•      Contract when calcium ions interact with calmodulin
•    Activates myosin light chain kinase
•      Functions over a wide range of lengths
•    Plasticity
•      Multi-unit smooth muscle cells are innervated by more than one motor neuron
•      Visceral smooth muscle cells are not always innervated by motor neurons
•    Neurons that innervate smooth muscle are not under voluntary control
The Muscular System


Muscle Organization and Function
Muscular system
•      Includes all skeletal muscle tissue that can be controlled voluntarily

Organization of skeletal muscle fibers
•      Parallel muscle
•      Convergent muscle
•      Pennate muscle
•    Unipennate
•    Bipennate
•    Multipennate
•      Circular muscle (sphincter)

Levers
•      Rigid structure that moves on a fixed point, the fulcrum
•      Changes direction and strength of applied force
•      Changes distance and speed of movement
•      Three classes
•    First class
•    Second class
•    Third class
•    Most common in the body

Muscle Terminology
Origins and Insertions
•      Muscles can be identified by origin, insertion and action
•    Origin = stationary end
•    Insertion = movable end

Actions
•      Muscles can be classified by action
•    Agonist (prime mover)
•    Antagonist
•    Synergist
•    Fixator

Names of skeletal muscles
•      Names give clues to muscle characteristics
•    Location
•    Fascicle organization
•    Relative position
•    Structure
•    Size
•    Shape
•    Origin and insertion
•    Action

Axial and Appendicular Muscles
•      Axial musculature arises on axial skeleton
•    Positions head and spinal column and moves the rib cage
•      Appendicular musculature moves and stabilizes components of the appendicular skeleton

The Axial Muscles
Axial muscles
•      Logical groupings based on location and/or function
•    Head and neck
•    Vertebral column
•    Oblique and rectus muscles
•    Pelvic floor

Muscles of the head and neck
•      Facial expression muscles
•    Orbicularis oris
•    Buccinator
•    Occipitofrontalis muscles
•    Platysma

Extrinsic eye muscles
(oculomotor or extra-ocular muscles)
•      Inferior and superior rectus muscles
•      Lateral and medial rectus muscles
•      Inferior and superior oblique muscles

Muscles of mastication
•      Masseter muscles
•      Temporalis muscles
•      Pterygoid muscles

Muscles of the tongue
(speech, swallowing and mastication)
•      Genioglossus
•      Hypoglossus
•      Palatoglossus
•      Styloglossus

Muscle of the pharynx
•      Pharyngeal constrictors
•      Laryngeal elevators
•      Palatal muscles

Muscle of the neck
•      Control the position of the larynx
•      Depress the mandible
•      Provide a foundation for the muscles of the tongue
•    Digastric and sternocleidomastoid muscles
•    Seven muscles that originate or insert on the hyoid
Muscles of the vertebral column
•      Superficial muscles of the spine
•    Spinalis
•    Longissimus
•    Iliocostalis

Muscles of the vertebral column
•      Neck region
•    Longus capitus
•    Longus colli
•      Lumbar region
•    Quadratus lumborum

Oblique and rectus muscles
•      Oblique
•    Scalene muscles
•    Intercostal muscles
•    Transverses muscles
•      External and internal intercostals
•      Diaphragm

Muscles of the pelvic floor
•      Perineum
•    Anterior urogenital triangle
•    Posterior anal triangle
•      Pelvic floor
•    Urogenital diaphragm
•    Pelvic diaphragm


The Appendicular Muscles
Muscles of the shoulders and upper arms
•      Trapezius muscles
•    Affect the position of the shoulder girdle, head and neck
•      Muscles inserting on the scapula
•    Rhomboid muscles
•    Levator scapulae muscles
•    Serratus anterior muscles
•    Subclavius muscles
•    Pectoralis minor muscles
•      Adductors
•    Deltoid muscles
•    Supraspinatus muscles
•      Medial rotators
•    Subscapularis muscles
•    Teres major muscles
•      Lateral rotation
•    Infraspinatus muscles
•    Teres minor muscles

More shoulder movements
•      Flexion and adduction
•    Coracobrachialis
•      Flexion of the shoulder joint
•    Pectoralis major muscles
•      Extension of the shoulder joint
•    Latissimus dorsi  muscles

Muscles that affect the elbow
•      Biceps brachii  muscle
•      Triceps brachii muscle
•      Brachialis and brachioradialis flex the elbow
•      Aconeus muscle extends the elbow

Muscles that affect the wrist
•      Flexion of the wrist
•    Flexor carpi ulnaris
•    Flexor carpi radialis
•    Palmaris longus
•      Extension of the wrist
•    Extensor carpi radialis
•    Extensor carpi ulnaris

Muscles that affect the forearm
•      Pronation of the forearm
•    Pronator teres muscle
•    Pronator quadratus muscle
•      Supination of the forearm
•    Supinator muscle

Muscles of the pelvis and lower limbs
•      Gluteal muscles cover the lateral surfaces of the ilia
•    Gluteus maximus (shares an insertion with the tensor fasciae latea)
•    Pulls on the iliotibial tract

Lateral rotators of the leg
•      Piriformis muscle
•      Obturator muscles

Adductors perform a variety of functions
Iliopsoas muscle
•      Formed from the merging of the psoas major and the iliacus muscles
•      Powerful flexor of the hip

Flexors of the knee
•      The hamstrings
•    Biceps femoris muscles
•    Semimembranosus muscles
•    Semitendinosis muscles
•      Popliteus muscle unlocks the knee joint

Extensors of the knee
•      Quadriceps femoris
•    Three vastus muscles
•    Rectus femoris muscle

Movements at the ankle
•      Plantar flexion
•    Gastrocnemius muscle
•    Soleus muscle
•      Eversion and plantar flexion
•    Fibularis muscle
•      Foot position and toe movement is accomplished by muscles originating on the talus and metatarsal bones

Aging and the Muscular System
With aging
•      Power and size of muscle tissue decrease
•      Skeletal muscles undergo fibrolysis
•      Tolerance for exercise decreases
•      Repair of injuries slows
Notes for ANATOMY & PHYSIOLOGY II
Blood

The Cardiovascular System: An Introduction
The cardiovascular system
•Provides a mechanism for rapid transport of nutrients, waste products, respiratory gases and cells

Functions and Composition of Blood
Blood
•Fluid connective tissue
•Functions include
•Transporting dissolved gases, nutrients, hormones, and metabolic wastes
•Regulating pH and ion composition of interstitial fluids
•Restricting fluid loss at injury sites
•Defending the body against toxins and pathogens
•Regulating body temperature by absorbing and redistributing heat

The composition of blood
•Plasma and formed elements comprise whole blood
•Red blood cells (RBC)
•White blood cells (WBC)
•Platelets
•Can fractionate whole blood for analytical or clinical purposes

Hemopoiesis
•Process of blood cell formation
•Hemocytoblasts are circulating stem cells that divide to form all types of blood cells
•Whole blood from anywhere in the body has roughly the same temperature, pH and viscosity

Plasma
•Accounts for 46-63% of blood volume
•92% of plasma is water
•Higher concentration of dissolved oxygen and dissolved proteins than interstitial fluid

Plasma proteins
•more than 90% are synthesized in the liver
•Albumins
•60% of plasma proteins
•Responsible for viscosity and osmotic pressure of blood

Additional Plasma Proteins
•Globulins
•~35% of plasma proteins
•Include immunoglobins which attack foreign proteins and pathogens
•Include transport globulins which bind ions, hormones and other compounds
•Fibrinogen
•Converted to fibrin during clotting
•Removal of fibrinogen leaves serum

Red Blood Cells
Abundance of RBCs
•Erythrocytes account for slightly less than half the blood volume, and 99.9% of the formed elements
•Hematocrit measures the percentage of whole blood occupied by formed elements
•Commonly referred to as the volume of packed red cells

Structure of RBCs
•Biconcave disc, providing a large surface to volume ration
•Shape allows RBCs to stack, bend and flex
•RBCs lack organelles
•Typically degenerate in about 120 days.

Hemoglobin
•Molecules of hemoglobin account for 95% of the proteins in RBCs
•Hemoglobin is a globular protein, formed from two pairs of polypeptide subunits
•Each subunit contains a molecule of heme which reversibly binds an oxygen molecule
•Damaged or dead RBCs are recycled by phagocytes

RBC life span and circulation
•Replaced at a rate of approximately 3 million new blood cells entering the circulation per second.
•Replaced before they hemolyze
•Components of hemoglobin individually recycled
•Heme stripped of iron and converted to biliverdin, then bilirubin
•Iron is recycled by being stored in phagocytes, or transported throughout the blood stream bound to transferrin

RBC Production
•Erythropoeisis = the formation of new red blood cells
•Occurs in red bone marrow
•Process speeds up with in the presence of EPO (Erythropoeisis stimulating hormone)
•RBCs pass through reticulocyte and erythroblast stages

Blood types
•Determined by the presence or absence of surface antigens (agglutinogens)
•Antigens A, B and Rh (D)
•Antibodies in the plasma (agglutinins)
•Cross-reactions occur when antigens meet antibodies

The White Blood Cells
Leukocytes
•Have nuclei and other organelles
•Defend the body against pathogens
•Remove toxins, wastes, and abnormal or damaged cells
•Are capable of amoeboid movement (margination) and positive chemotaxis
•Some are capable of phagocytosis

Types of WBC
•Granular leukocytes
•Neutrophils – 50 to 70 % total WBC population
•Eosinophils – phagocytes attracted to foreign compounds that have reacted with antibodies
•Basophils – migrate to damaged tissue and release histamine and heparin

Types of WBC
•Agranular leukocytes
•Monocytes  - become macrophage
•Lymphocytes – includes T cells, B cells, and NK cells

Differential count
•Indicates a number of disorders
•Leukemia = inordinate number of leukocytes
WBC Production
•Granulocytes and monocytes are produced by bone marrow stem cells
•Divide to create progenitor cells
•Stem cells may originate in bone marrow and migrate to peripheral tissues
•Several colony stimulating factors are involved in regulation and control of production

Platelets
•Flattened discs
•Circulate for 9-12 days before being removed by phagocytes

Platelet functions
•Transporting chemicals important to clotting
•Forming temporary patch in walls of damaged blood vessels
•Contracting after a clot has formed

Platelet production (thrombocytopoiesis)
•Megakaryocytes release platelets into circulating blood
•Rate of platelet formation is stimulated by thrombopoietin, thrombocyte-stimulating factor, interleukin-6, and Multi-CSF

Hemostasis
•Prevents the loss of blood through vessel walls
•Three phases –
•Vascular phase
•Platelet phase
•Coagulation phase

Hemostasis
•Vascular phase
•Local blood vessel constriction (vascular spasm)
•Platelet phase
•Platelets are activated, aggregate at the site, adhere to the damaged surfaces

Coagulation phase
•Factors released by platelets and endothelial cells interact with clotting factors to form a clot
•Extrinsic pathway
•Intrinsic pathway
•Common pathway
•Suspended fibrinogen is converted to large insoluble fibrin fibers

Clot retraction
•Final phase of healing
•Platelets contract and pull the edges of the vessel together

Fibrinolysis
•Clot gradually dissolves through action of plasmin
•Activated form of plasminogen
•Clotting can be prevented through the use of drugs that depress the clotting response or dissolve existing clots
•Anticoagulants include heparin, coumadin, aspirin, dicumarol, t- PA, streptokinase, and urokinase

The Heart

Organization of the Cardiovascular System
The cardiovascular system is divided into two circuits
•Pulmonary circuit
•blood to and from the lungs
•System circuit
•blood to and from the rest of the body
•Vessels carry the blood through the circuits
•Arteries carry blood away from the heart
•Veins carry blood to the heart
•Capillaries permit exchange

Anatomy of the Heart
The pericardia
•Visceral pericardium or epicardium
•Parietal pericardium
•Pericardial fluid

Superficial Anatomy of the Heart
•The heart consists of four chambers
•Two atria and two ventricles
•Major blood vessels of the heart include
•Inferior and superior vena cavae
•Aorta and pulmonary trunk

The Heart Wall
•Components of the heart wall include
•Epicardium
•Myocardium
•Endocardium

Internal Anatomy and Organization
•Atria
•Thin walled chambers that receive blood from the vena cavae
•Ventricles
•Thick walled chambers separated from the atria by AV valves
•Chordae tendineae
•Tendinous fibers  attached to the AV valves
•Papillary muscle and trabeculae carneae
•Muscular projections on the inner wall of ventricles

Blood flow through the heart
•Right atria
•Tricuspid valve
•Right ventricle
•Pulmonary valve
•Pulmonary circuit
•Left atria
•Bicuspid valve
•Left ventricle
•Aortic valve
•Aorta and systemic circuit

Heart chambers and valves
•Structural Differences in heart chambers
•The left side of the heart is more muscular than the right side
•Functions of valves
•AV valves prevent backflow of blood from the ventricles to the atria
•Semilunar valves prevent backflow into the ventricles from the pulmonary trunk and aorta

Connective Tissues
•Connective tissue fibers of the heart
•Provide physical support and elasticity
•Distribute the force of contraction
•Prevent overexpansion
•The fibrous skeleton
•Stabilizes the heart valves
•Physically isolates atrial from ventricular cells

Blood Supply to the Heart
•Arteries include the right and left coronary arteries, marginal arteries, anterior and posterior interventricular arteries, and the circumflex artery
•Veins include the great cardiac vein,  anterior and posterior cardiac veins, the middle cardiac vein, and the small cardiac vein

The Heartbeat
Cardiac Physiology
•Two classes of cardiac muscle cells
•Specialized muscle cells of the conducting system
•Contractile cells

The Conducting System
•The conducting system includes:
•Sinoatrial (SA) node
•Atrioventricular (AV) node
•Conducting cells
•Atrial conducting cells are found in internodal pathways
•Ventricular conducting cells consist of the AV bundle, bundle branches, and Purkinje fibers

Impulse Conduction through the heart
•SA node begins the action potential
•Stimulus spreads to the AV node
•Impulse is delayed at AV node
•Impulse then travels through ventricular conducting cells
•Then distributed by Purkinje fibers

The electrocardiogram (ECG)
•A recording of the electrical events occurring during the cardiac cycle
•The P wave accompanies the depolarization of the ventricles
•The QRS complex appears as the ventricles depolarize
•The T wave indicates ventricular repolarization

Contractile Cells
•Resting membrane potential of approximately –90mV
•Action potential
•Rapid depolarization
•A plateau phase unique to cardiac muscle
•Repolarization
•Refractory period follows the action potential

Calcium Ion and Cardiac contraction
•Cardiac action potentials cause an increase in Ca2+ around myofibrils
•Ca2+ enters the cell membranes during the plateau phase
•Additional Ca2+ is released from reserves in the sarcoplasmic reticulum

The cardiac cycle
•The period between the start of one heartbeat and the beginning of the next
•During a cardiac cycle
•Each heart chamber goes through systole and diastole
•Correct pressure relationships are dependent on careful timing of contractions

Pressure and volume changes: atrial systole
•rising atrial pressure pushes blood into the ventricle
•atrial systole
•the end-diastolic volume (EDV) of blood is in the ventricles

Pressure and volume changes: ventricular systole
•Isovolumetric contraction of the ventricles: ventricles are contracting but there is no blood flow
•Ventricular pressure increases forcing blood through the semilunar valves

Pressure and volume changes: ventricular diastole
•The period of isovolumetric relaxation when all heart valves are closed
•Atrial pressure forces the AV valves open

Heart sounds
•Auscultation – listening to heart sound via stethoscope
•Four heart sounds
•S1 – “lubb” caused by the closing of the AV valves
•S2 – “dupp” caused by the closing of the semilunar valves
•S3 – a faint sound associated with blood flowing into the ventricles
•S4 – another faint sound associated with atrial contraction

Cardiodynamics
Stroke Volume and Cardiac Output
•Cardiac output – the amount of blood pumped by each ventricle in one minute
•Cardiac output equals heart rate times stroke volume

Factors Affecting Heart Rate
•Autonomic innervation
•Cardiac reflexes
•Tone
•SA node
•Hormones
•Epinephrine (E), norepinephrine(NE), and thyroid hormone (T3)
•Venous return

Medulla Oblongata centers affect autonomic innervation
•Cardioacceleratory center activates sympathetic neurons
•Cardioinhibitory center controls parasympathetic neurons
•Receives input from higher centers, monitoring blood pressure and dissolved gas concentrations

Basic heart rate established by pacemaker cells
•SA node establishes baseline
•Modified by ANS
•Atrial reflex

Factors Affecting stoke volume
•EDV
•Frank-Starling principle
•ESV
•Preload
•Contractility
•Afterload

Autonomic Activity
•Sympathetic stimulation
•Positive inotropic effect
•Releases NE
•Parasympathetic stimulation
•Negative inotropic effect
•Releases ACh

Exercise and Cardiac Output
•Heavy exercise can increase output by 300-500 percent
•Trained athletes may increase cardiac output by 700 percent
•Cardiac reserve
•The difference between resting and maximal cardiac output

Summary: Regulation of Heart Rate and Stroke Volume
•Sympathetic stimulation increases heart rate
•Parasympathetic stimulation decreases heart rate
•Circulating hormones, specifically E, NE, and T3, accelerate heart rate
•Increased venous return increases heart rate
•EDV is determined by available filling time and rate of venous return
•ESV is determined by preload, degree of contractility, and afterload

The Heart and the Cardiovascular System
The heart is part of the cardiovascular system
•The goal of the cardiovascular system is to maintain adequate blood flow to all body tissues
•The heart works in conjunction with cardiovascular centers and peripheral blood vessels to achieve this goal

Blood Vessels and Circulation

The Anatomy of Blood Vessels
Structure of vessel walls
•Walls of arteries and veins contain three distinct layers
•Tunic intima
•Tunica media
•Tunica externa

Differences between arteries and veins
•Compared to veins, arteries
•Have thicker walls
•Have more smooth muscle and elastic fibers
•Are more resilient

Arteries
•Undergo changes in diameter
•Vasoconstriction – decreases the size of the lumen
•Vasodilation – increases the size of the lumen
•Classified as either elastic (conducting) or muscular (distribution)
•Small arteries (internal diameter of 30 um or less) are called arterioles

Capillaries
•An endothelial tube inside a basal lamina
•These vessels
•Form networks
•Surround muscle fibers
•Radiate through connective tissue
•Weave throughout active tissues
•Capillaries have two basic structures
•Continuous
•Fenestrated
•Flattened fenestrated capillaries = sinusoids

Capillary Beds
•An interconnected network of vessels consisting of
•Collateral arteries feeding an arteriole
•Metarterioles
•Arteriovenous anastomoses
•Capillaries
•Venules

Veins
•Collect blood from all tissues and organs and return it to the heart
•Are classified according to size
•Venules
•Medium-sized veins
•Large veins

Venous Valves
•Venules and medium-sized veins  contain valves
•Prevent backflow of blood

Distribution of blood
•Total blood volume is unevenly distributed
•Venoconstriction maintains blood volume
•Veins are capacitance vessels
•Capacitance = relationship between blood volume and pressure

Cardiovascular Physiology
Circulatory Pressure
•Circulatory pressure is divided into three components
•Blood pressure (BP)
•Capillary hydrostatic pressure (CHP)
•Venous pressure

Resistance (R)
•Resistance of the cardiovascular system opposes the movement of blood
•For blood to flow, the pressure gradient must overcome total peripheral resistance
•Peripheral resistance (PR) is the resistance of the arterial system

Overview of Cardiovascular Pressures
•Factors involved in cardiovascular pressures include
•Vessel diameter
•Cross-sectional area of vessels
•Blood pressure
•Blood viscosity

Arterial blood pressure
•Arterial blood pressure
•Maintains blood flow through capillary beds
•Rises during ventricular systole and falls during ventricular diastole
•Pulse is a rhythmic pressure oscillation that accompanies each heartbeat
•Pulse pressure = difference between systolic and diastolic pressures


Mean arterial pressure (MAP)

Capillary Exchange
•Flow of water and solutes from capillaries to interstitial space
•Plasma and interstitial fluid are in constant communication
•Assists in the transport of lipids and tissue proteins
•Accelerates the distribution of nutrients
•Carries toxins and other chemical stimuli to lymphoid tissues

Processes that move fluids across capillary walls
•Diffusion
•Filtration
•Hydrostatic pressure (CHP)
•Reabsorption

Forces acting across capillary walls
•Capillary hydrostatic pressure  (CHP)
•Blood colloid osmotic pressure  (BCOP)
•Interstitial fluid colloid osmotic pressure (ICOP)
•Interstitial fluid hydrostatic pressure (IHP)

Filtration and reabsorption
•Processes involved in filtration and reabsorption include
•Net hydrostatic pressure
•CHP - IHP
•Net colloid osmotic pressure
•BCOP - ICOP

Venous pressure and venous return
•Assisted by two processes
•Muscular compression
•The respiratory pump

Cardiovascular Regulation
•Autoregulation
•Neural mechanisms
•Endocrine mechanisms

Autoregulation of blood flow within tissues
•Local vasodilators accelerate blood flow in response to:
•Decreased tissue O2 levels or increased CO2 levels
•Generation of lactic acid
•Release of nitric acid
•Rising K+ or H+ concentrations in interstitial fluid
•Local inflammation
•Elevated temperature

Neural Mechanisms
•Adjust CO and PR to maintain vital organ blood flow
•Medullary centers of regulatory activity include
•Cardiac centers
•Vasomotor centers control
•Vasoconstriction via adrenergic release of NE
•Vasodilation via direct or indirect release of NO

Reflex control of cardiovascular function
•Baroreceptors reflexes monitor stretch
•Atrial baroreceptors  monitor blood pressure
•Chemoreceptor reflexes monitor CO2, O2, or pH levels

Hormones and cardiovascular regulation
•Antidiuretic hormone – released in response to decreased blood volume
•Angiotensin II – released in response to a fall in blood pressure
•Erythropoietin – released if BP falls or O2 levels are abnormally low
•Natriuretic peptides – released in response to excessive right atrial stretch

Patterns of Cardiovascular Response
Exercise and the Cardiovascular System
•Light exercise results in
•Extensive vasodilation
•Increased venous return
•A rise in cardiac output
•Heavy exercise results in
•Increased blood flow to skeletal muscles
•Restriction of blood flow to nonessential organs

Cardiovascular response to hemorrhaging: short term
•Carotid and aortic reflexes increase CO and peripheral vasoconstriction
•Sympathetic nervous system elevates blood pressure
•E and NE increase cardiac output and ADH enhances vasoconstriction

Cardiovascular response to hemorrhaging: long term
•Decline in capillary blood pressure recalls fluids from interstitial spaces
•Aldosterone and ADH promote fluid retention
•Increased thirst promotes water absorption across the digestive tract
•Erythropoietin ultimately increases blood volume and improves O2 delivery

Special circulation
•The brain
•Four arteries which anastomose insuring constant blood flow
•The heart
•Coronary arteries arising from the ascending aorta
•The lungs
•Pulmonary circuit, regulated by local responses to O2 levels
•Opposite other tissues (declines in O2 cause vasodilation)

The Distribution of Blood Vessels: An Overview
The distribution of blood: General functional patterns
•Peripheral distribution of arteries and veins is generally symmetrical
•Except near the heart
•Single vessels may have several names as they cross anatomical boundaries
•Arteries and corresponding veins usually travel together

The Pulmonary Circuit
Pulmonary circuit consists of pulmonary vessels
•Arteries which deliver blood to the lungs
•Capillaries in the lungs where gas exchange occurs
•Veins which deliver blood to the left atrium

The Systemic Circuit
Systemic arteries
•Ascending aorta
•Right and left coronary arteries originate from base of aortic sinus
•Aortic arch and branches
•Brachiocephalic
•Left common carotid
•Left subclavian arteries
•Descending aorta and its branches
•Thoracic and abdominal aortas

Systemic Veins
•Superior vena cava
•Drains blood from the head and neck
•Inferior vena cava
•Drains blood from the remainder of the body

Hepatic Portal System
•Contains substance absorbed by the stomach and intestines
•Delivers these compounds to the liver for
•Storage
•Metabolic conversion
•Excretion

Fetal Circulation
Placental Supply
•Fetal blood flow to the placenta is supplied via paired umbilical arteries
•A single umbilical vein drains from the placenta to the ductus venosus
•Collects blood from umbilical vein and liver
•Empties into the inferior vena cava

Fetal Circulation of the Heart and Great Vessels
•No need for pulmonary function in the fetus
•Two shunts bypass the pulmonary circuit
•Foramen ovale
•Ductus arteriosus

Cardiovascular Changes at Birth
•Lungs and pulmonary  vessels expand
•Ductus arteriosus constricts and becomes ligamentum arteriosum
•A valvular flap closes the foramen ovale

Aging and the Cardiovascular System
Age-related changes in blood may include
•Decreased hematocrit
•Constriction or blockage of peripheral veins by a thrombus
•Pooling of blood in the veins of the legs
•Vessels are less elastic, prone to Ca2+ deposits and thrombi formation

The Lymphatic System and Immunity

An Overview of the Lymphatic System and Immunity
lymphatic system
•The lymphatic system
•Contains cells, tissues, and organs responsible for defending the body
•Lymphocytes resist infection and disease by responding to
•Invading pathogens such as bacteria or viruses
•Abnormal body cells such as cancer cells
•Foreign proteins such as toxins

Organization of the Lymphatic System
The lymphatic system consists of
•Lymph
•Lymphatic vessels
•Lymphoid tissues and organs
•Lymphocytes and supporting phagocytic cells

Functions of lymphatic system
•Primary function is production, maintenance, and distribution of lymphocytes
•Lymphocytes must:
•Detect where problems exist
•Be able to reach the site of injury or infection

Lymphatic vessels include
•Lymphatic capillaries
•Small lymphatic vessels
•Major lymph-collecting vessels

Major lymph-collecting vessels
•Superficial and deep lymphatics
•Thoracic duct
•Cisterna chyli
•Right lymphatic duct

Lymphocytes
•Three classes of lymphocytes
•T (thymus dependent) cells
•B (bone marrow-derived) cells
•NK (natural killer) cells

Lymphocyte production (lymphopoiesis)
•Involves bone marrow, thymus, and peripheral lymphoid tissue
•B cells and NK cells mature in bone marrow
•T cells mature in the thymus

Lymphoid tissue
•Connective tissue dominated by lymphocytes
•Lymphoid nodules
•Lymphocytes densely packed in areolar tissue
•Found in the respiratory, digestive, and urinary tracts
•MALT  (mucosa-associated lymphoid tissue)
•Collection of lymphoid tissues linked with the digestive system

Lymphoid organs
•Lymph nodes – function in the purification of lymph
•Afferent lymphatics – carry lymph to nodes
•Efferent lymphatics – carry lymph from nodes
•Deep cortex dominated by T cells
•Outer cortex and medulla contains B cells

The Lymphatic System and Immunity
The Thymus
•Located behind sternum in anterior mediastinum
•Capsule
•Two lobes
•Divided into lobules, each with a cortex and medulla
•Cortical lymphocytes surrounded by reticular endothelial cells
•Maintain blood–thymus barrier
•Secretes thymic hormones: thymosins, thymopoietins, and thymulin

The Spleen
•Largest mass of lymphoid tissue
•Cellular components form pulp
•Red pulp contains RBC
•White pulp similar to lymphoid nodules
•Spleen functions include
•Removal of abnormal blood cells and other blood components
•Storage of iron
•Initiation of the specific immune response

Lymphatic system and body defenses
•Nonspecific defenses
•Do not distinguish one type of threat from another
•7 types
•Specific defenses
•Protect against particular threats
•Depend upon the activation of lymphocytes

Nonspecific Defenses
Nonspecific Defenses, Physical barriers
•Keep hazardous organisms outside the body
•Includes hair, epithelia, secretions of integumentary and digestive systems

(Part 1 - Physical Barriers)
Nonspecific Defenses, Phagocytes
•Remove cellular debris and respond to invasion by foreign pathogens
•Monocyte-macrophage system - Fixed and free
•Microphages – Neutrophils and eosinophils
•Move by diapedesis
•Exhibit chemotaxis

(Part 2 - Phagocytes)
Nonspecific Defenses, Immunological surveillance
•Constant monitoring of normal tissue by NK cells
•NK cells
•Recognize cell surface markers on foreign cells
•Destroy cells with foreign antigens

NK cell activation
•Recognition of unusual surface proteins
•Rotation of the Golgi toward the target cell and production of perforins
•Release of perforins by exocytosis
•Interaction of perforins causing cell lysis

(Part 3 - Immunological Surveillance)
Nonspecific Defenses, Interferons (cytokines)
•Small proteins released by virally infected cells
•Trigger the production of antiviral proteins
•Three major types of interferons are:
•Alpha– produced by leukocytes and attract/stimulate NK cells
•Beta– secreted by fibroblasts causing slow inflammation
•Gamma – secreted by T cells and NK cells stimulate macrophage activity

(Part 4 - Interferons)
Nonspecific Defenses, Complement system
•Cascade of ~11 plasma complement proteins (C)
•Destroy target cell membranes
•Stimulate inflammation
•Attract phagocytes
•Enhance phagocytosis

Complement proteins interact with on another via two pathways
•Classical
•Alternative

(Part 5 - Complement System)
Nonspecific Defenses, Inflammation
•Localized tissue response to injury producing
•Swelling
•Redness
•Heat
•Pain
•Effects of inflammation include
•Temporary repair of injury
•Slowing the spread of pathogens
•Mobilization of local, regional, and systemic defenses

(Part 6 - Inflammatory Response)
Nonspecific Defenses, Fever
•Maintenance of a body temperature above 37.2oC (99oF)
•Pyrogens reset the hypothalamic thermostat and raise body temperature
•Pathogens, toxins, antigen-antibody complexes can act as pyrogens

 (Part 7 - Fever)

Specific Defenses
Forms of immunity
•Innate immunity
•Genetically determined
•Present at birth
•Acquired immunity
•Not present at birth
•Achieved by exposure to antigen
•Active immunity
•Passive immunity

Properties of immunity
•Specificity – activated by and responds to a specific antigen
•Versatility – is ready to confront any antigen at any time
•Memory – “remembers” any antigen it has encountered
•Tolerance – responds to foreign substances but ignores normal tissues

The immune system response
•Antigen triggers an immune response
•Activates T cells and B cells
•T cells are activated after phagocytes exposed to antigen
•T cells attack the antigen and stimulate B cells
•Activated B cells mature and produce antibody
•Antibody attacks antigen

T cells and Cell-mediated Immunity
Major types of T cells
•Cytotoxic T cells (TC) – attack foreign cells
•Helper T cells (TH) – activate other T cells and B cells
•Suppressor T cells (TS) – inhibit the activation of T and B cells

Antigen presentation
•Antigen-glycoprotein combination appears on a cell membrane
•Called MHC proteins (Major Histocompatibility Complex)
•Coded for by genes of the MHC
•T-cells sensitive to the antigen are activated upon contact

MHC classes
•Class I – found on all nucleated cells
•Class II – found on antigen presenting cells and lymphocytes

Lymphocytes respond to antigens bound to either class I or class II MHC proteins
•Antigen recognition
•T cell membranes contain CD markers
•CD3 markers present on all T cells
•CD8 markers on cytotoxic and suppressor T cells
•CD4 markers on helper T cells

Activation of CD8 cells
•Responds quickly giving rise to other T cells
•Cytotoxic T cells – seek out and destroy abnormal cells
•lymphotoxin
•Memory TC cells – function during a second exposure to antigen
•Suppressor T cells – suppress the immune response

Activation of CD4 T cells by antigens presented on class II MHC proteins
•Produces helper T cells and memory T cells
•Activated helper T cells
•Secrete lymphokines that coordinate specific and nonspecific defenses
•Enhance nonspecific defenses
•Stimulate the activity of NK cells
•Promote activation of B cells

B Cells and Antibody-mediated Immunity
B cell sensitization of activation
•Sensitization – the binding of antigens to the B cell membrane antibodies
•Antigens then displayed on B cell Class II MHC
•TH cells activated by same antigen stimulate B cell
•Active B cell differentiates into Memory B Cell or Plasma cell
•Plasma cells synthesize and release antibody

Antibodies structure
•Antibodies are  Y-shaped proteins consisting of:
•Two parallel polypeptide chains
•Heavy chains and light chains
•Constant region and variable region
•Antigen binding site

Actions of antibodies include:
•Neutralization
•Agglutination and precipitation
•Activation of complement
•Attraction of phagocytes
•Opsinization
•Stimulation of inflammation
•Prevention of adhesion

Classes of Antibodies (immunoglobins)
•IgG – resistance against many viruses, bacteria and bacterial toxins
•IgE – accelerates local inflammation
•IgD – found on the surface of B cells
•IgM – first type secreted after antigen arrives
•IgA – primarily found in glandular sec

Primary and secondary antibody response
•Primary response
•Takes about two weeks to develop
•Produced by plasma cells
•Secondary response
•Rapid increase in IgG
•Maximum antibody titer app

Focus on Hormones of the Immune System
•Interleukins
•Increase T cell sensitivity
•Stimulate B cell activity, plasma formation, and antibody production
•Enhance nonspecific defenses
•Moderate the immune system
•Interferons
•Tumor Necrosis Factors (TNFs) slow tumor growth
•Colony Stimulating Factors (CSFs)

Normal and Abnormal Resistance
Development of the Immune Response
•Immunological competence
•The ability to demonstrate an immune response after exposure to an antigen
•Fetuses receive immunity from the maternal bloodstream
•Infants acquire immunity following exposure

Immune disorders
•Autoimmune disorders
•Immune response mistakenly targets normal cells
•Immunodeficiency diseases
•Immune system does not develop properly or is blocked

Allergies
•Inappropriate or excessive immune response to allergens
•Immediate hypersensitivity (type I)
•Cytotoxic reactions (type II)
•Immune complex disorders (type III)
•Delayed hypersensitivity (type IV)
•Anaphylaxis
•Circulating allergen affects mast cells throughout body

Stress and the immune response
•Interleukin-1 released by active macrophages
•Triggers release of ACTH resulting in glucocorticoid release
•Moderates the immune response
•Lowers resistance to disease

Stress can cause the following:
•Depression of the inflammatory response
•Phagocytic reduction
•Inhibition of interleukin secretion

Aging and the Immune Response
With age
•Immune system becomes less effective
•Increased susceptibility to infection
•Immune surveillance declines

The Respiratory System

The Respiratory System: An Introduction
Functions of the respiratory system
•Gas exchange between air and circulating blood
•Moving air from the exchange surface of the lungs
•Protection of respiratory surfaces
•Production of sound
•Provision for olfactory sensations

Organization of the respiratory system
•Upper respiratory system
•Nose, nasal cavity, paranasal sinuses, pharynx
•Lower respiratory system
•Larynx, trachea, bronchi, bronchioles, alveoli

The Respiratory tract
•Conducting passageways carrying air to and from the alveoli
•Upper respiratory passages filter and humidify incoming air
•Lower passageways include delicate conduction passages and alveolar exchange surfaces

Respiratory Mucosa
•Respiratory epithelium and underlying connective tissue
•Respiratory membrane, supported by lamina propria, changes along tract
•Lines conducting portion of respiratory tract
•Protected from contamination by respiratory defense system

The Upper Respiratory System
The nose and nasal cavity consists of:
•External nares
•Nasal cavity
•Vestibule
•Superior, middle and inferior meatuses
•Hard and soft palates
•Internal nares
•Nasal mucosa

The pharynx
•Shared by the digestive and respiratory systems
•Divided into three sections:
•Nasopharynx – superior portion
•Oropharynx – continuous with the oral cavity
•Laryngopharynx – between the hyoid bone and the esophagus

The Larynx

•Air passes through the glottis on the way to the lungs
•Larynx protects the glottis
•Cartilages of the larynx
•Three large cartilages
•Thyroid, cricoid, and epiglottis
•Paired cartilages
•Arytenoids, corniculate, and cuneiform

Folds of the larynx
•Inelastic vestibular folds
•Delicate vocal folds

Sound production
•Air passing through the glottis vibrates the vocal folds producing sound waves
•Pitch depends on conditions of vocal folds
•Diameter
•Length
•Tension

The laryngeal musculature
•Muscles of the neck and pharynx position and stabilize the larynx
•When swallowing,these muscles
•Elevate the larynx
•Bend the epiglottis over the glottis
•Intrinsic muscles control tension on the vocal folds and open the glottis

The Trachea and Primary Bronchi
The trachea
•Extends from the sixth cervical vertebra to the fifth thoracic vertebra
•A tough, flexible tube running from the larynx to the bronchi
•Held open by C-shaped tracheal cartilages in submucosa
•Mucosa is similar to the nasopharynx

The primary bronchi
•Trachea branches in the mediastinum into right and left bronchi
•Bronchi enter the lungs at the hilus
•Root = the connective tissue mass including:
•Bronchus
•Pulmonary vessels
•Nerves

The Lungs
Lobes and surfaces of the lungs
•Lobes of the lung are separated by fissures
•Right lung has three lobes
•Left lung has two lobes
•Concavity on medial surface = cardiac notch

The bronchial tree
•System of tubes formed from the primary bronchi and their branches
•Primary bronchi branch into secondary or lobar bronchi
•Secondary bronchus goes to each lobe of the lungs
•Secondary bronchi branch into tertiary bronchi
•Tertiary bronchi supply air to a single bronchopulmonary segment
•Cartilage in walls decrease and smooth muscle increase with branching

The bronchioles
•Ultimately branch into terminal bronchioles
•Delivers air to a single pulmonary lobule
•Terminal bronchiole becomes respiratory bronchioles
•Connective tissue of root branches to form interlobar septa

Alveolar ducts and alveoli
•Respiratory bronchioles end in ducts and sacs
•Respiratory exchange surfaces connected to circulatory system via pulmonary circuit

Respiratory Membrane
•Simple squamous epithelium
•Endothelial cell lining an adjacent capillary
•Fused basal laminae

Cells of the respiratory membrane include
•Septal cells
•Scattered in respiratory membrane
•Produce surfactant
•Alveolar Macrophage
•Patrol epithelium and engulf foreign particles

The blood supply to the lungs
•Conducting portions
•Receive blood from external carotids, thyrocervical, bronchial arteries
•Respiratory exchange surfaces
•receive blood from the arteries of the pulmonary circuit
•are the source of angiotensin-converting enzyme (ACE)
•Pulmonary veins return blood to the left atrium

The pleural cavities and pleural membranes
•Each lung covered by one pleura
•Pleura – serous membranes lining the pleural cavity
•Parietal -  attaches to the walls of the pleural cavity
•Visceral -  adheres to the surface of the lungs
•Pleural fluid – fills and lubricates the space between the pleura

An Overview of Respiratory Physiology
Respiratory physiology is a series of integrated processes
•Internal respiration
•Exchange of gases between interstitial fluid and cells
•External respiration
•Exchange of gases between interstitial fluid and the external environment
•The steps of external respiration include:
•Pulmonary ventilation
•Gas diffusion
•Transport of oxygen and carbon dioxide

Pulmonary Ventilation

•The physical movement of air into and out of the lungs

Air movement
•Movement of air depends upon
•Boyle’s Law
•Pressure and volume inverse relationship
•Volume depends on movement of diaphragm and ribs
•Pressure and airflow to the lungs
•Compliance – an indication of the expandability of the lungs

Pressure changes during inhalation and exhalation
•Relationship between intrapulmonary pressure and atmospheric pressure determines direction of air flow
•Intrapleural pressure maintains pull on lungs
•Pressure in the space between parietal and visceral pleura
Respiratory cycle
•Single cycle of inhalation and exhalation
•Amount of air moved in one cycle = tidal volume

Mechanisms of breathing
•Quiet breathing (eupnea)
•Diaphragm and external and internal intercostals muscles
•Forced breathing (hyperpnea)
•Accessory muscles

Respiratory volumes
•Alveolar volume
•Amount of air reaching the alveoli each minute
•Tidal Volume (VT)
•Amount of air inhaled or exhaled with each breath
•Vital capacity
•Tidal volume plus expiratory and inspiratory reserve volumes
•Residual volume
•Air left in lungs after maximum exhalation

Gas Exchange
The gas laws
•Daltons Law and partial pressure
•Individual gases in a mixture exert pressure proportional to their abundance
•Diffusion between liquid and gases (Henry’s law)
•The amount of gas in solution is directly proportional to their partial pressure

Diffusion and respiratory function
•Gas exchange across respiratory membrane is efficient due to:
•Differences in partial pressure
•Small diffusion distance
•Lipid-soluble gases
•Large surface area of all alveoli
•Coordination of blood flow and airflow

Gas Pickup and Delivery
Blood in peripheral capillaries delivers O2 and absorbs CO2
•Reactions are completely reversible

Oxygen transport
•Carried mainly by RBCs, bound to hemoglobin
•The amount of oxygen hemoglobin can carried is dependent upon:
•PO2
•pH
•temperature
•BPG
•Fetal hemoglobin has a higher O2 affinity than adult hemoglobin

Carbon dioxide transport
•7% dissolved in plasma
•70% carried as carbonic acid
•buffer system
•23% bound to hemoglobin
•carbaminohemoglobin
•Plasma transport

Summary of gas transport
•Driven by differences in partial pressure
•Oxygen enters blood at lungs and leaves at tissues
•Carbon dioxide enters at tissues and leaves at lungs

Control of Respiration
Gas absorption/generation balanced by capillary rates of delivery/removal
•Homeostatic mechanisms maintain balance
•Local regulation of gas transport and alveolar function include
•Lung perfusion
•Alveolar capillaries constrict in low oxygen
•Alveolar ventilation
•Bronchioles dilate in high carbon dioxide

Respiratory centers of the brain
•Medullary centers
•Respiratory rhythmicity centers set pace
•Pons
•Apneustic and pneumotaxic centers

Respiratory reflexes
•Respiratory centers are modified by sensory information including
•Chemoreceptor reflexes
•Level of carbon dioxide
•Baroreceptors reflexes
•Hering-Breuer reflexes
•Prevents overinflation
•Protective reflexes

Voluntary control of respiration
•Regulation of respiratory rate is dependent upon:
•Conscious and unconscious thought
•Emotional state
•Anticipation

Changes in the Respiratory System at Birth
Neonatal Respiration
•Upon taking the first breath:
•Inhaled air enters the respiratory passages for the first time
•The bronchial tree and most of the alveoli are inflated
•Subsequent breaths complete inflation of the alveoli

Aging and the Respiratory System
The efficiency of the respiratory system decreases with age as:
•Elastic tissue deteriorates causing lower lung compliance and vital capacity
•Chest movements are restricted by arthritic changes
•Some degree of emphysema normally occurs

Metabolism and Energetics

An Overview of Metabolism
Metabolism
•Metabolism is all the chemical reactions that occur in an organism
•Cellular metabolism
•Cells break down excess carbohydrates first, then lipids
•Cells conserve amino acids
•40% of the energy released in catabolism is captured in ATP
•Rest is released as heat

Anabolism
•Performance of structural maintenance and repairs
•Support of growth
•Production of secretions
•Building of nutrient reserves

Cells and Mitochondria
•cells provide small organic molecules for their mitochondria
•Mitochondria produce ATP used to perform cellular functions

Carbohydrate Metabolism
Most cells generate ATP through the breakdown of carbohydrates
•Glycolysis
•One molecule of glucose = two pyruvate ions, two ATP, two NADH
•Aerobic metabolism (cellular respiration)
•Two pyruvates = 34 ATP
•The chemical formula for this process is
     C6H12O6 + 6 O2  6 CO2  + 6 H2O

Glycolysis
•The breakdown of glucose to pyruvic acid
•This process requires:
•Glucose molecules
•Cytoplasmic enzymes
•ATP and ADP
•Inorganic phosphate
•NAD (nicotinamide adenine dinucleotide)
•The overall reaction is:
     Glucose + 2 NAD + 2 ADP + 2Pi  
     2 Pyruvic acid + 2 NADH + 2 ATP


Mitochondrial ATP Production
(cellular respiration)
•Pyruvic acid molecules enter mitochondria
•Broken down completely in TCA cycle
•Decarboxylation
•Hydrogen atoms passed to coenzymes
•Oxidative phosphorylation

Oxidative phosphorylation and the ETS
•Requires coenzymes and consumes oxygen
•Key reactions take place in the electron transport system (ETS)
•Cytochromes of the ETS pass electrons to oxygen, forming water
•The basic chemical reaction is:
                          2 H2 + O2    2 H2O
•Per molecule of glucose entering these pathways
•Glycolysis – has a net yield of 2 ATP
•Electron transport system – yields approximately 28 molecules of ATP
•TCA cycle – yields 2 molecules of ATP

Synthesis of glucose and glycogen
•Gluconeogenesis
•Synthesis of glucose from noncarbohydrate precursors
•Lactic acid, glycerol, amino acids
•Liver cells synthesis glucose when carbohydrates are depleted
•Glycogenesis
•Formation of glycogen
•Glucose stored in liver and skeletal muscle as glycogen
•Important energy reserve

Lipid catabolism
•Lipolysis
•Lipids broken down into pieces that can be converted into pyruvate
•Triglycerides are split into glycerol and fatty acids
•Glycerol enters glycolytic pathways
•Fatty acids enter the mitochondrion

Lipid catabolism
•Beta-oxidation
•Breakdown of fatty acid molecules into
2-carbon fragments
•Enter the TCA
•Irreversible
•Lipids and energy production
•Cannot provide large amounts in ATP in a short amount of time
•Used when glucose reserves are limited
•Almost any organic molecule can be used to form glycerol
•Essential fatty acids cannot be synthesized and must be included in diet
•Linoleic and linolenic acid

Lipid transport and distribution
•5 types of lipoprotein
•Lipid-protein complex that contains large glycerides and cholesterol
•Chylomicrons
•Largest lipoproteins composed primarily of triglycerides
•Very low-density lipoproteins (VLDLs)
•contain triglycerides, phospholipids and cholesterol

Lipid transport and distribution
•5 types of lipoprotein (continued)
•Intermediate-density lipoproteins (IDLs)
•Contain smaller amounts of triglycerides
•Low-density lipoproteins (LDLs)
•Contain mostly cholesterol
•High-density lipoproteins (HDLs)
•Equal amounts of lipid and protein

Lipoprotein lipase
•Enzyme that breaks down complex lipids
•Found in capillary walls of liver, adipose tissue, skeletal and cardiac muscle
•Releases fatty acids and monglycerides

Protein Metabolism
Amino acid catabolism
•If other sources inadequate, mitochondria can break down amino acids
•TCA cycle
•removal of the amino group (-NH2)
•Transamination – attaches removed amino group to a keto acid
•Deamination – removes amino group generating NH4+
•Proteins are an impractical source of ATP production

Protein synthesis
•Essential amino acids
•Cannot be synthesized by the body in adequate supply
•Nonessential amino acids
•Can be synthesized by the body via amination
•Addition of the amino group to a carbon framework

Nucleic Acid Metabolism

•Nuclear DNA is never catabolized for energy
•RNA catabolism
•RNA molecules are routinely broken down and replaced
•Generally recycled as nucleic acids
•Can be catabolized to simple sugars and nitrogenous bases
•Do not contribute significantly to energy reserves

Nucleic acid synthesis
•Most cells synthesis RNA
•DNA synthesized only when preparing for division

Metabolic Interactions
Homeostasis
•No one cell of the human body can perform all necessary homeostatic functions
•Metabolic activities must be coordinated

Body has five metabolic components
•Liver
•The focal point for metabolic regulation and control
•Adipose tissue
•Stores lipids primarily as triglycerides
•Skeletal muscle
•Substantial glycogen reserves

Body has five metabolic components
•Neural tissue
•Must be supplied with a reliable supply of glucose
•Other peripheral tissues
•Able to metabolize substrates under endocrine control

The absorptive state
•The period following a meal
•Nutrients enter the blood as intestinal absorption proceeds
•Liver closely regulates glucose content of blood
•Lipemia commonly marks the absorptive state
•Adipocytes remove fatty acids and glycerol from bloodstream
•Glucose molecule are catabolized and amino acids are used to build proteins

The Postabsorptive state
•From the end of the absorptive state to the next meal
•Body relies on reserves for energy
•Liver cells break down glycogen, releasing glucose into blood
•Liver cells synthesize glucose
•Lipolysis increases and fatty acids released into blood stream
•Fatty acids undergo beta oxidation and enter TCA

The Postabsorptive state
•Amino acids either converted to pyruvate or acetyl-CoA
•Skeletal muscles metabolize ketone bodies and fatty acids
•Skeletal muscle glycogen reserves broken down to lactic acid
•Neural tissue continues to be supplied with glucose

Diet and Nutrition
•Nutrition
•Absorption of nutrients from food
•Balanced diet
•Contains all the ingredients necessary to maintain homeostasis
•Prevents malnutrition

Food
•Food groups and food pyramids
•Used as guides to avoid malnutrition

Food Groups
•Six basic food groups of a balance diet arranged in a food pyramid
•Milk, yogurt and cheese
•Meat, poultry, fish, dry beans, eggs, and nuts
•Vegetables
•Fruits
•Bread, cereal, rice and pasta
•Base of pyramid
•Fats, oils and sweets
•Top of pyramid

Nitrogen balance
•N compounds contain nitrogen
•Amino acids, purines, pyrimidines, creatine, porphyrins
•Body does not maintain large nitrogen reserves
•Dietary nitrogen is essential
•Nitrogen balance is an equalization of absorbed and excreted nitrogen

Minerals
•Act as co-factors in enzymatic reactions
•Contribute to osmotic concentrations of body fluids
•Play a role in transmembrane potentials, action potentials
•Aid in release of neurotransmitters and muscle contraction
•Assist in skeletal construction and maintenance
•Important in gas transport and buffer systems
•Aid in fluid absorption and waste removal

Vitamins
•Are needed in very small amounts for a variety of vital body activities
•Fat soluble
•Vitamins A, D, E, K
•Taken in excess can lead to hypervitaminosis
•Water soluble
•Not stored in the body
•Lack of adequate dietary intake = avitaminosis

Bioenergetics
•The study of acquisition and use of energy by organisms
•Energy content of food expressed in Calories per gram (C/g)

Food and energy
•Catabolism of lipids yields 9.46 C/g
•Catabolism of proteins and carbohydrates yields ~4.7 C/g

Metabolic rate
•Total of all anabolic and catabolic processes underway
•Basal metabolic rate (BMR) is the rate of energy used by a person at rest

Thermoregulation
•Homeostatic regulation of body temperature
•Heat exchange with the environment involves four processes:
•Radiation
•Conduction
•Convection
•Evaporation

Regulation of heat gain and loss
•Preoptic area of hypothalamus acts as thermostat
•Heat-loss center
•Heat-gain center
•Mechanisms for increasing heat loss include:
•Peripheral vasodilation
•Increase perspiration
•Increase respiration
•Behavioral modifications

Mechanisms promoting heat gain
•Decreased blood flow to the dermis
•Countercurrent heat exchange
•Shivering thermogenesis and nonshivering thermogenesis
•Differs by individuals due to acclimatization

Thermoregulation
•Problems in infants
•Lose heat quickly due to their small size
•Do not shiver
•Use brown fat to accelerate lipolysis - energy escapes as heat
•Variations in adults
•Use subcutaneous fat as an insulator
•Different hypothalamic thermostatic settings

Pyrexia is elevated body temperature
•Fever is body temperature greater than 37.2oC
•Can result from a variety of situations including:
•Heat exhaustion or heat stroke
•Congestive heart failure
•Impaired sweat gland activity
•Resetting of the hypothalamic thermostat by circulating pyrogens


The Urinary System

An Overview of the Urinary System
Functions of the urinary system
•Excretion
•The removal of organic waste products from body fluids
•Elimination
•The discharge of waste products into the environment
•Homeostatic regulation of blood plasma
•Regulating blood volume and pressure
•Regulating plasma ion concentrations
•Stabilizing blood pH
•Conserving nutrients

Urinary system includes:
•The kidneys
•Produce urine
•The ureters
•The urinary bladder
•Stores urine
•The urethra

The kidneys
•Left kidney extends slightly more superiorly than right
•Both kidneys and adrenal glands are retroperitoneal
•Hilus
•Entry for renal artery and renal nerves
•Exit for renal veins and ureter

Sectional anatomy of the kidneys
•Superficial outer cortex and inner medulla
•The medulla consists of 6-18 renal pyramids
•The cortex is composed of roughly 1.25 million nephrons
•Major and minor calyces along with the pelvis drain urine to the ureters

Blood supply and innervation of the kidneys
•Renal arteries branch repeated
•Renal artery
•Segmental artery
•Interlobar artery
•Arcuate artery
•Interlobular artery
•Afferent arterioles
•Renal venules follow similar opposing pattern ending with renal veins

The nephron consists of a renal corpuscle and renal tubule
•The renal corpuscle is composed of
•Bowman’s capsule and the glomerulus
•The renal tubule consists of
•Proximal convoluted tubule (PCT)
•Loop of Henle
•Distal convoluted tubule (DCT)

Filtrate is produced at the renal corpuscle
•Nephron empties tubular fluid into collecting system
•Collecting ducts and papillary ducts

Nephron functions include:
•Production of filtrate
•Reabsorption of organic nutrients
•Reabsorption of water and ions
•Secretion of waste products into tubular fluid

Two types of nephron
•Cortical nephrons
•~85% of all nephrons
•Located in the cortex
•Juxtamedullary nephrons
•Closer to renal medulla
•Loops of Henle extend deep into renal pyramids

Renal tubule and blood flow
•Blood travels from efferent arteriole to peritubular capillaries
•Vasa recta
•Renal tubule begins at renal corpuscle
•Includes glomerulus and Bowman’s capsule
•Blood leaves the nephron via the efferent arteriole

Glomerulus anatomy
•Podocytes cover lamina densa of capillaries
•Project into the capsular space
•Pedicels of podocytes separated by filtration slits


Functional anatomy of the nephron
•Proximal convoluted tubule (PCT)
•Actively reabsorbs nutrients, plasma proteins and ions from filtrate
•Released into peritubular fluid
•Loop of Henle
•Descending limb
•Ascending limb
•Each limb has a thick and thin section

Functional anatomy of the nephron
•Distal convoluted tubule (DCT)
•Actively secretes ions, toxins, drugs
•Reabsorbs sodium ions from tubular fluid

Principles of Renal Physiology
Urine production maintains homeostasis
•Regulating blood volume and composition
•Excreting waste products
•Urea
•Creatinine
•Uric acid

Basic processes of urine formation
•Filtration
•Blood pressure
•Water and solutes across glomerular capillaries
•Reabsorption
•The removal of water and solutes from the filtrate
•Secretion
•Transport of solutes from the peritubular fluid into the tubular fluid

Carrier Mediated Transport
•Filtration in the kidneys modified by carrier mediated transport
•Facilitated diffusion
•Active transport
•Cotransport
•Countertransport
•Carrier proteins have a transport maximum (Tm)
•Determines renal threshold

Reabsorption and secretion
•Accomplished via diffusion, osmosis, and carrier-mediated transport
•Tm determines renal threshold for reabsorption of substances in tubular fluid

Renal function
•Most regions of the nephron perform a combination of functions
•General functions can be identified
•Filtration in the renal corpuscle
•Nutrient reabsorption along the PCT
•Active secretion at PCT and DCT
•Loops of Henle regulate final volume and solute concentration

Renal Physiology: Filtration and the Glomerulus
Filtration pressures - Glomerular filtration
•Occurs as fluids move across the glomerulus
•In response to glomerular hydrostatic pressure (GHP) and blood pressure in the glomerular capillaries
•Capsular hydrostatic pressure (CsHP) opposes GHP
•Blood colloid osmotic pressure (BCOP) opposes GHP
•Net hydrostatic pressure (NHP)  = GHP – CsHP
•Filtration (FP)  = NHP – BCOP

Glomerular filtration rate (GFR)
•Amount of filtrate produced in the kidneys each minute
•Factors that alter filtration pressure change GFR

Factors controlling the GFR
•A drop in filtration pressure stimulates Juxtaglomerular apparatus (JGA)
•Releases renin and erythropoietin

Sympathetic activation
•Produces powerful vasoconstriction of afferent arterioles
•Decreases GFR and slows production of filtrate
•Changes the regional pattern of blood flow
•Alters GFR
•Stimulates release of renin by JGA


Renal Physiology: Reabsorption and Secretion
Reabsorption and secretion at the PCT
•Glomerular filtration produces fluid similar to plasma without proteins
•The PCT reabsorbs 60-70% of the filtrate produced
•Reabsorption of most organic nutrients
•Active and passive reabsorption of sodium and other ions
•Reabsorption of water
•Secretion also occurs in the PCT

The loop of Henle and countercurrent multiplication
•Countercurrent multiplication
•Between ascending and descending limbs of loop
•Creates osmotic gradient in medulla
•Facilitates reabsorption of water and solutes before the DCT
•Permits passive reabsorption of water from tubular fluid

Reabsorption and secretion at the DCT
•DCT performs final adjustment of urine
•Active secretion or absorption
•Absorption
•Tubular cells actively resorb Na+ and Cl-
•In exchange for potassium or hydrogen ions (secreted)

Reabsorption and secretion along the collecting system
•Water and solute loss is regulated by aldosterone and ADH
•Reabsorption
•Sodium ion, bicarbonate, and urea are resorbed
•Secretion
•pH is controlled by secretion of hydrogen or bicarbonate ions

Control of urine volume and osmotic concentration
•Urine volume and osmotic concentration are regulated by controlling water reabsorption
•Precise control allowed via facultative water reabsorption

Function of the vasa recta
•Removes solutes and water
•Balances solute reabsorption and osmosis in the medulla

Composition of normal urine
•Varies with the metabolic and hormonal events of the body
•Reflects filtration, absorption and secretion activity of the nephrons
•Urinalysis is the chemical and physical analysis of urine

Summary of renal function:
•Each segment of nephron and collecting system contribute
•Glomerulus
•PCT
•Descending limb
•Thick ascending limb
•DCT and collecting ducts
•Concentrated urine produced after considerable modification of filtrate

Urine Transport, Storage, and Elimination
Urine production ends with fluid entering the renal pelvis
•Rest of urinary system transports, stores and eliminates
•Ureters
•Bladder
•Urethra

The ureters
•Pair of muscular tubes
•Extend from renal pelvis to the bladder
•Peristaltic contractions force urine toward the urinary bladder

The urinary bladder
•Hollow, muscular organ
•Reservoir for the storage of urine
•Contraction of detrusor muscle voids bladder
•Internal features include
•Trigone
•Neck
•Internal urethral sphincter
•Ruggae

The urethra
•Extends from the urinary bladder to the exterior of the body
•Passes through urogenital diaphragm (external urinary sphincter)
•Differs in length and function in males and females

Micturition reflex and urination
•Urination coordinated by micturition reflex
•Initiated by stretch receptors in wall of bladder
•Urination requires coupling micturition reflex with relaxation of external urethral sphincter

Aging and the Urinary System
Changes with aging include:
You should now be familiar with:
•The components of the urinary system and their functions
•The location and structural features of the kidneys
•The structure of a nephron, and the processes involved in the formation of urine
•The normal characteristics, composition, and solute concentrations of a representative urine sample

The Reproductive System

•Reproductive system functions in gamete
•Production
•Storage
•Nourishment
•Transport
•Fertilization
•Fusion of male and female gametes to form a zygote

Introduction to the Reproductive System
Reproductive system includes:
•Gonads (testes, ovaries)
•Ducts
•Accessory glands and organs
•External genitalia
•
Males and Females
•Males
•Testes produce spermatozoa
•Expelled from body in semen during ejaculation
•Females
•Ovaries produce oocytes
•Immature ovum
•Travels along uterine tube toward uterus
•Vagina connects uterus with exterior of body

The Reproductive System of the Male
Male Reproductive System
•Pathway of spermatozoa
•Epididymis
•Ductus deferens
•Ejaculatory duct
•Accessory organs
•Seminal vesicles
•Prostate gland
•Bulbourethral glands
•Scrotal sac encloses testes
•Penis

The testes
•Descent of the testes
•Movement of testes through inguinal canal into scrotum
•Occurs during fetal development
•Testes remain connected to internal structures
•Spermatic cords

Male Anatomy
•Musculature of scrotal sac
•Dartos muscle wrinkles scrotal sac
•Cremaster muscle pulls sac close to body
•Testes anatomy
•Tunica albuginea surrounds testis
•Septa extend from tunica albuginea to epididymus
•Lobules

Sperm production
•In seminiferous tubules
•Interstitial cells between seminiferous tubules
•Secrete sex hormones
•Sperm pass through rete testis
•Efferent ductules connect rete testis to epididymus

Spermatogenesis
•Seminiferous tubules
•Contain spermatogonia
•Stem cells involved in spermatogenesis
•Contain sustentacular cells
•Sustain and promote development of sperm

Spermatogenesis
•Spermatogenesis involves three processes
•Mitosis
•Meiosis
•Spermiogenesis

Anatomy of spermatozoon
•Each spermatozoon has:
•Head
•Nucleus and densely packed chromosomes
•Middle piece
•Mitochondria that produce the ATP needed to move the tail
•Tail
•The only flagellum in the human body

Male reproductive tract
•Testes produce mature spermatozoa
•Sperm enter epididymus
•Elongated tubule with head, body and tail regions
•Monitors and adjusts fluid in seminiferous tubules
•Stores and protects spermatozoa
•Facilitates functional maturation of spermatozoa

Ductus deferens AKA vas deferens
•Begins at epididymus
•Passes through inguinal canal
•Enlarges to form ampulla
•Ejaculatory duct at base of seminal vesicle and ampulla
•Empties into urethra

Urethra
•Urinary bladder to tip of penis
•Three regions
•Prostatic
•Membranous
•Penile

Accessory glands
•Seminal vesicles
•Active secretory gland
•Contributes ~60% total volume of semen
•Secretions contain fructose, prostaglandins, fibrinogen

Accessory glands
•Prostate gland
•Secretes slightly acidic prostate fluid
•Bulbourethral glands
•Secrete alkaline mucus with lubricating properties

Contents of Semen
•Typical ejaculate = 2-5 ml fluid
•Contains between 20 – 100 million spermatozoa per ml
•Seminal fluid
•A distinct ionic and nutritive glandular secretion

External genitalia
•Male external genitalia consist of the scrotum and the penis
•Skin overlying penis resembles scrotum
•Penis
•Contains three masses of erectile tissue
•2 corpora cavernosa beneath fascia
•1 corpus spongiosum surrounding urethra
•Dilation of erectile tissue produces erection

Hormones and male reproductive function
•FSH (Follicle stimulating hormone)
•Targets sustentacular cells to promote spermatogenesis
•LH (leutinizing hormone)
•Causes secretion of testosterone and other androgens
•GnRH (Gonadotropin releasing hormone)
•Testosterone
•Most important androgen

The Reproductive System of the Female
Principle organs of the female reproductive system
•Ovaries
•Uterine tubes
•Uterus
•Vagina

Support and stabilization
•Ovaries, uterine tubes and uterus enclosed within broad ligament
•Mesovarium supports and stabilizes ovary

The ovaries
•Held in position by ovarian and suspensory ligaments
•Blood vessels enter at ovarian hilus
•Tunica albuginea covers ovary
•Ovum production
•Occurs monthly in ovarian follicles
•Part of ovarian cycle
•Follicular phase (preovulatory)
•Luteal phase (postovulatory)

The ovarian cycle
•Steps in the ovarian cycle
•Formation of primary, secondary, and tertiary follicles
•Ovulation
•Formation and degeneration of the corpus luteum
•Degradation of the corpus luteum

The Uterine tubes
•Uterine tubes (Fallopian tubes or oviducts)
•Infundibulum
•End closest to the ovary with numerous fimbriae
•Ampulla
•The middle portion
•Isthmus
•A short segment connected to the uterine wall

Each uterine tube opens directly into uterine cavity
•Fertilization occurs in uterine tube
•12-24 hours after ovulation
•During passage from infundibulum to uterus

The uterus
•Muscular organ
•Mechanical protection
•Nutritional support
•Waste removal for the developing embryo and fetus
•Supported by the broad ligament and 3 pairs of suspensory ligaments

Uterus
•Major anatomical landmarks
•Body
•Isthmus
•Cervix
•Cervical os (internal orifice)
•Uterine cavity
•Cervical canal
•Internal os (internal orifice)

Uterine wall consists of three layers:
•Myometrium – outer muscular layer
•Endometrium – a thin, inner, glandular mucosa
•Perimetrium – an incomplete serosa continuous with the peritoneum
•Repeating series of changes in the endometrium

Uterine cycle
•Repeating series of changes in the endometrium
•Continues from menarche to menopause
•Menses
•Degeneration of the endometrium
•Menstruation
•Proliferative phase
•Restoration of the endometrium
•Secretory phase
•Endometrial glands enlarge and accelerate their rates of secretion

The vagina
•Major functions
•Passageway for elimination of menstrual fluids
•Receives the penis during sexual intercourse
•Forms the inferior portion of the birth canal

External genitalia
•Vulva
•Vestibule
•Labia minora and majora
•Paraurethral glands
•Clitoris
•Lesser and greater vestibular glands

Mammary glands
•Pectoral fat pad
•Nipple surrounded by the areola
•Function in lactation under control of reproductive hormones

Hormones of the female reproductive cycle
•Control the reproductive cycle
•Coordinate the ovarian and uterine cycles

Hormones of the female reproductive cycle
•Key hormones include:
•FSH
•Stimulates follicular development
•LH
•Maintains structure and secretory function of corpus luteum
•Estrogens
•Have multiple functions
•Progesterones
•Stimulate endometrial growth and secretion

The Physiology of Sexual Intercourse
Male sexual function
•Arousal
•Leads to erection of the penis
•Parasympathetic outflow over the pelvic nerves
•Emission and ejaculation
•Occur under sympathetic stimulation
•Results in semen being pushed toward external urethral opening
•Detumescence
•Subsidence of erection
•Mediated by the sympathetic nervous system

Female sexual function
•Stages are comparable to those of male sexual function
•Arousal causes clitoral erection
•Vaginal surfaces are moistened
•Parasympathetic stimulation causes engorgement of blood vessels in the nipples

Aging and the Reproductive System
Menopause
•The time that ovulation and menstruation cease
•Typically around age 45-55
•Accompanied by a decline in circulating estrogen and progesterone
•Rise in GnRH, FSH, LH

Male climacteric
•Levels of circulating testosterone begin to decline
•FSH and LH levels rise
•Gradual reduction in sexual activity


Development and Inheritance

The Second and Third Trimesters

•Second trimester
•Organ systems increase in complexity
•Third trimester
•Many organ systems become fully functional
•Fetus undergoes largest weight change
•At end of gestation fetus and uterus push maternal organs out of position

Developing fetus totally dependent on  maternal organs
•Maternal adaptations include increased
•Respiratory rate
•Tidal volume
•Blood volume
•Nutrient and vitamin uptake
•Glomerular filtration rate
•
Structural and Functional Changes in the Uterus
•Progesterone inhibits uterine muscle contraction
•Opposed by estrogens, oxytocin and prostaglandins
•Multiple factors interact to produce labor contractions in uterine wall

Labor and Delivery
Goal of labor is parturition
•Stages of labor
•Dilation
•The cervix dilates and fetus moves toward cervical canal
•Expulsion
•The cervix completes dilation and fetus emerges
•Placental
•Ejection of the placenta

Other labor and delivery situations
•Premature labor
•True labor begins before fetus has completed normal development
•Difficult deliveries
•When the fetus faces the pubis rather than the sacrum
•The legs or buttocks enter the vaginal canal first (breech births)
•Multiple births
•Twins, triplets, etc.
•Dizygotic or monozygotic situations

Postnatal Development
Postnatal life stages
•Neonatal period
•Infancy
•Childhood
•Adolescence
•Maturity
•Senescence begins at maturity and ends in death
•
The neonatal period
•From birth to one month
•Respiratory, circulatory, digestive and urinary systems adjust
•Infant must thermoregulate
•Maternal mammary glands secrete colostrum first few days
•Milk production thereafter
•Both secretions are released via the milk let-down reflex
•Body proportions change during infancy and childhood

Adolescence
•Begins at puberty
•The period of sexual maturation
•Ends when growth is completed
•
Puberty marked by
•Increased production of GnRH
•Rapid increase in circulating FSH and LH
•Ovaries and testes become sensitive to FSH / LH
•Gamete production initiated
•Sex hormones produced
•Growth rate increases

Hormonal changes at puberty produce gender specific differences in system
•Differences are retained throughout life
•Adolescence continues until growth completed
•Further changes occur when sex hormones decline
•Menopause
•Male climacteric

Senescence
•Aging affects functional capabilities of all system

Genetics, Development, and Inheritance
Genes and chromosomes
•Every somatic cell carries copies of the 46 original chromosomes in the zygote
•Genotype – Chromosomes and their component genes
•Phenotype – physical expression of the genotype
•
Patterns of inheritance
•Somatic cells contain 23 pairs of chromosomes
•Homologous chromosomes
•22 pair of autosomes and one pair of sex chromosomes
•Chromosomes contain DNA
•Genes are functional segments of DNA

Various forms of a gene are called alleles
•Homozygous if homologous chromosomes carry the same alleles
•Heterozygous if homologous chromosomes carry different alleles
•Alleles are either dominant or recessive depending on expression
•Punnett square diagram predicts characteristics of offspring

Inheritance
•Simple inheritance
•Phenotypic characteristics are determined by interactions between single pair of alleles
•Polygenic inheritance
•Phenotypic characteristics are determined by interactions among alleles on several genes
•
Sources of individual variation
•Genetic recombination
•Gene reshuffling
•Crossing over and translocation
•Occurs during meiosis
•Spontaneous mutations
•Random errors in DNA replication

Sex-linked inheritance
•Sex chromosomes are X chromosome and Y chromosome
•Male = XY
•Female = XX
•X chromosome carries X-linked (sex linked) genes
•Affect somatic structures
•Have no corresponding alleles on Y chromosome

The Human Genome Project
•Mapped more than 38,000 of our genes
•Including some responsible for inherited disorders

You should now be familiar with:
•The relationship between differentiation and development, and the various stages of development
•The process of fertilization
•The three prenatal periods and describe the major events associated with each
•The importance of the placenta as an endocrine organ
•
You should now be familiar with:
•The structural and functional changes in the uterus during gestation
•The events that occur during labor and delivery
•The basic principles of genetics as they relate to the inheritance of human traits