NERVOUS SYSTEM 1

I.   ORGANIZATION

A.  Central vs. Peripheral Nervous System

1.  Central Nervous System (CNS): brain and spinal cord

 

2.  Peripheral Nervous System (PNS): cranial nerves, spinal nerves, ganglia

* (Ganglion=group of neuron cell bodies located outside CNS)

B:  Sensory (afferent) division vs. Motor (efferent) division:

1.  Sensory Division: receives  information FROM body and transmits it TO the CNS for processing

a)  Somatic Sensory: receives sensory info from skin, joints, muscle, special senses

 

b)  Visceral Sensory: receives sensory info from blood vessels, viscera

 

2.  Motor Division: transmits info FROM the CNS TO muscles and glands

a.  Somatic motor component: innervates skeletal muscle

 

b.  Autonomic motor (Autonomic Nervous System): innervates smooth muscle, cardiac muscle, and glands of viscera (organs)

II.  NERVOUS TISSUE CELLS
A.  Neurons: respond to stimuli and conduct nerve impulses

B.  Glial Cells: support and protect neurons

III. NEURON COMPOSITION
A.  Cell Body:

* function:

B.  Nucleus, with nucleolus

C.  Chromatophilic substances: rough ER
* function:

D.  Dendrites:
* function:

E.  Axon:
*  function:

F.  Axon Hillock: portion of cell body from where axon originates

IV.  NEURON CLASSIFICATION
A.  By Structure:

1.  Multipolar Neuron: one axon and many dendrites

 

 

2.  Bipolar Neuron: two processes: one axon and one dendrite

 

 

3.  Unipolar (Pseudounipolar) Neuron: single process comes off of the cell body and divides into two branches

 

 

B.  By Function:

1.  Sensory (afferent) Neuron: brings information TO the CNS

 

2.  Motor (efferent) Neuron: takes information FROM CNS to other parts of the body

 

 

3.  Interneuron: helps coordinate and integrate info between sensory and motor neurons

 

 

 

 

 

V.   GLIAL CELLS

-- in PNS:                                     
A.  Satellite Cells: surround neuron cell bodies in spinal ganglia

B. Neurolemmocytes (Schwann cells): myelinate axons in PNS

-- in CNS:
C.  Astrocytes: regulate transfer of materials from blood to the brain - help the workings of  “blood -brain barrier”

D.  Oligodendrocytes: myelinate axons in CNS

E.  Microglia: phagocytize damaged neurons

F.  Ependymal Cells: line central canal and ventricles - help circulate cerebrospinal fluid (CSF)

This type of glial cell myelinates axons in the PNS.

a. neurolemmocyte

b. astrocyte

c. ependymal cell

d. oligodendrocyte

e. satellite cell

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