Human Anatomy and Physiology I
Review Sheet for Lecture Exam 2.

 

The Skeletal System

The skeletal system includes about 206 bones.  These can be classified according to:
Cranial vs. Postcranial
Axial vs. Appendicular

The functions of the skeletal system include:

Support of the body, providing shape.
Protection of soft parts.
Movement - redirection of forces generated by the contraction of skeletal muscle.
Hemopoiesis - production of blood cells.
Mineral sink - storage of calcium and phosphate.
 
Development of bone.
There are two types of bone based on developmental pattern:
Endochondral bone - preformed in cartilage
Intramembranous or dermal bone - formed directly in connective tissue membranes of dermis.

Bones can be classified on the basis of their shape:
Long bones                            Irregular bones.
Short bones                           Flat bones
Know an example of each.

Structure of a typical long bone.

Know the following terms:
   diaphysis                                endosteum
   epiphysis                                medullary cavity
   metaphysis                            red marrow
   periostium                              yellow marrow
   articular cartilage

Bone tissue.
Know the following cell types, their functions and locations where they are found:
   osteocyte
   osteoblast
   osteoclast
Structure of compact bone:
   Haversian canal (= central canal)                lacunae
   lamellae                                                          Osteon (= haversian system)
   canaliculi                                                         Perforating canals (= Volkman's canals)


Know the sequence of events that occurs during the growth of a long bone:
1. Cartilaginous model             4. Secondary ossification center
2. Calcification                           5. Epiphyseal plate (Metaphysis).
3. Primary ossification center 
 
Know the processes that occur within the epiphyseal plate (including the zones of growth),
     and remodeling.

 Know the classification of bone breaks and the process of healing:
Closed (Simple) fracture                      Open (Compound) fracture             Complete fracture
Greenstick fracture                                Transverse fracture                          Incomplete fracture
Fissured fracture                                   Oblique fracture
Comminuted fracture                            Spiral fracture

Articulations

Classification:
     Fibrous joints - fibrous (collagenous) connective tissue.
     Cartilaginous joints - fibrocartilage.
     Synovial joints - synovial membrane and synovial fluid.

Know structure and examples of each type.

 Know the different types of synovial joints:
     Gliding                        Condyloid
     Hinge                          Saddle
     Pivot                           Ball-and-socket
Be able to give an example of each.

The Muscular System
Functions:
   Motion
   Heat production
   Posture and support
 
Basic muscle architecture.
There are several different ways a muscle can connect to other parts of the body: Tendon,
   aponeurosis, or direct attachment.
 
Every muscle has two points of connection, an origin and an insertion.  The muscle mass
   between these points is called the belly.
 
A muscle is covered by a thin layer of connective tissue called the epimysium. 
Within the muscle, there are smaller divisions called fascicles, these are separated by a
   perimysium.
Each fascicle is composed of a large number of individual fibers (muscle cells) separated
   by an endomysium.

Individual muscle fibers are syncitia (multinucleate cells), with specialized organelles.  Know the following:
Sarcoplasm                                      Transverse tubules
Sarcolemma                                     Myofibrils
Sarcoplasmic reticulum                  Myofilaments
Sarcomere                                        Actin
Terminal cisternae                           Myosin

Sarcomere structure.  Know:
   Z line                           actin (thin myofilaments)
   A band                        myosin fibers (thick myofilaments)
   I band                          m line
   H zone
 
Sliding filament theory of muscle contraction. Understand how this works and what
evidence demonstrates that actin and myosin myofilaments actually slide together
during muscle contraction.

 Know how the following structures result in myofilament sliding:
Cross bridges                                   tropomyosin
Myosin head                                     troponin
actin-binding site

    Sequence of events:

1.      a nerve impulse causes Ca++ ions to be released from the terminal cisternae of the
sarcoplasmic reticulum.

2.      Ca++ binds to troponin, causing a conformational change in the troponin - tropomyosin
complex that exposes the active site on the actin molecule.

3.      The myosin cross bridge, which has been activated by the decomposition of ATP into
ADP + P, immediately binds to the active site on the actin filament.

   4.      The cross bridge undergoes a conformational change which results in a sliding of the
   actin and myosin myofilaments closer together. This also causes the ADP and P to be released
   from the myosin cross bridge, making it available for another reaction.

   5. Contraction ceases when nerve impulses stop stimulating the muscle and Ca++ ions are
   pumped into the sarcoplasmic reticulum, where they remain bound to the protein 
   calsequestrin until the next nerve impulse arrives.  When Ca++ is no longer available, the  
   actin and myosin disengage as tropomyosin resumes its position over the active sites on 
   the actin molecule.

Contraction mechanics  - Know the following terms:


Muscle twitch                          Motor unit
summation                              isotonic contraction
incomplete tetanus                isometric contraction
complete tetanus                   treppe
 
Know the alternative sources of energy that are available to supply muscle contraction:
aerobic respiration –               know glycolysis, pyruvate, and the role of the mitochondria
anaerobic respiration –           know the roles of glycolysis and lactic acid
Phosphagen system –             know the roles of myokinase and creatine phosphate
What is oxygen debt?              What changes result from endurance training? Power training?
Know differences between Type I (red), Type IIA (intermediate) and Type IIB (white) fibers.
 
What are antagonists and synergists? agonists? fixators?
Know the differences between parallel, convergent, pennate (unipennate, bipennate and multipennate)
and sphincteral muscle types.  Know a few examples of each type.

The Nervous System
Functions: Communication system of body.  There are three types of impulses:
1)     Sensory impulses
2)     Motor impulses
3)     Integrative impulses

Classification of parts of Nervous System:
A.     Central nervous system
     1)     Brain
     2)     Spinal Cord
 
B.     Peripheral N.S.
     1)     Sensory Neurons
          a)     Somatic sensory neurons
          b)     Visceral sensory neurons
     2)     Motor Neurons
          a)     Somatic motor neurons
          b)     Autonomic motor neurons
               1.     Sympathetic neurons
               2.     Parasympathetic neurons

The Neuron.
Includes: Cell body (or soma or perikaryon), dendrites, axon.
 
Neurons may be bipolar (sensory neurons of retina), multipolar (typical motor neurons) or
     unipolar (typical sensory neurons).
Other cells associated w/ nervous system: Neuroglia.  6 types.
    Schwann cells – produce myelin sheaths of PNS
    Oligodendrogliocytes – produce myelin sheaths of CNS
    Microglia – small, phagocytic cells, protective in function
    Astrocytes – participate in formation of Blood Brain Barrier
    Ependymal cells – aid movement of cerebrospinous fluid within CNS
    Satellite (Ganglionic) cells – support neuron cell bodies within ganglia
 
Myelin sheaths insulate fibers within and outside of CNS.  These sheaths are separated
     from one another by small gaps called the Nodes of Ranvier, which allow rapid,
     saltatory conduction.

 Know the difference between white matter and gray matter.


Impulse conduction in nerve cells:
The sodium/potassium pump maintains a concentration gradient of Na+ and K+ ions across
     the nerve cell membrane.
Differences in the concentration of positive ions on either side of the membrane result in an
     electrical potential between inside & outside of the cell (usu. About –70 mV).
 
Depolarization is a sudden shift in the balance of ions such that the difference in electrical
     potential decreases between the two sides of the membrane

Hyperpolarization results in a greater charge differential.

Action potentials occur in an axon or axon hillock (trigger zone):
When the electrical potential of the plasma membrane of the soma adjacent to the axon hillock
     rises above -55 mV , then voltage regulated ion gates on the axon hillock open & allow
     a rapid influx of Na+ (depolarization), then a rapid efflux of K+ (repolarization).  Thus, the electrical
     resting potential is restored. 
The balance of ions is then restored by the sodium/potassium pump.
 
Action potentials are all-or-none events.  Each is followed by a refractory period during
     which balance of ions must be recovered.
 
Action potentials are self-propagating within an axon, and are irreversible.
Action potentials are also non-decremental.
 
Nerve impulses are transmitted from cell to cell by chemical messengers called
     neurotransmitters that must be released into the gap between two cells (called the synapse).
 
Axon terminals contain vesicles of neurotransmitter that are released by exocytosis when
     an action potential is received.

 Neurotransmitters, such as acetylcholine, cross the synapse by diffusion


           The receiving cell has special receptor proteins that bind with the neurotransmitter, causing
                the opening of ligand-regulated gates, allowing influx of Na+ and efflux of K+.

This initiates a response known as a local potential. 
Local potentials are graded: the more neurotranmitter, the stronger the potential.
Local potentials may be positive or negative, resulting in depolarization or hyperpolarization,
     respectively.
Local potentials are reversible.  Once initiated, the membrane potential will go back to the
     resting potential if stimulation stops before an action potential occurs.
Local potentials are decremental, losing strength as they move away from the site of the
     stimulus.
 
Neurotransmitters are rapidly broken down by enzymes of the postsynaptic cell (e.g.
acetylcholinesterase).
If enough local potentials are received, they may reach the axon hillock and stimulate an
action potential in the axon.

The Spinal Cord 

Know the basic structure of the spinal cord.
Conus medullaris                   anterior horns
Filum terminale                     posterior horns
Cauda equina                          lateral horns
Anterior median fissure            gray commissure
Posterior median sulcus            central canal

 Know the various spinal cord tracts and the regions that they serve.

Know the structure and function of spinal nerves and plexuses:
Posterior root                         Cervical plexus
Anterior root                            brachial plexus
Spinal ganglion                       Lumbar plexus
Anterior ramus                       Sacral plexus
Posterior ramus             
Rami communicantes
Sympathetic trunk ganglion
gray ramus
White ramus

Know how a reflex arc works.
Know the  difference between a  simple stretch reflex and a
       flexor and crossed extensor reflex.

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