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The Nervous System
functions and parts of the nervous system
22
Anatomy
12th Grade
12/06/2007

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Cards

Term
unipolor neurons
Definition
have a single process extending from cell body that divides into two processes a short distance from the cell body. one process extends to the periphery and the other to the CNS. most afferent neurons. recieves sensory information in the dendrite-like extensions and sends information to CNS.  
Term
neuroglia cells
Definition

more numerous than neurons. retain their ability to divide.

Term
astrocytes
Definition
star shaped. provide structural support for the CNS, form a layer around blood vessels and helps form the blood-brain barrier.
Term
ependymal cells
Definition
squamous epithelial like. line the ventricles of the brain and circulate the cerebrospinal fluid; some form the choroid plexus which produces CSF.
Term
microglial cells
Definition
small mobile cells. protection of the CNS from infection. phagocytic.
Term
oligodendrocytes
Definition
cells with processes that can surround several axons. cell processes form myelin sheaths around axon or enclose unmyelinated axons in the CNS.
Term
schwann cells
Definition
single cells surrounding axons. form myelin sheaths or enclose unmyelinated axons in the PNS.
Term
myelin sheath in PNS
Definition
schwann cells form the myelin sheath around some nerve fibers in the PNS.
Term
myelin sheath in CNS
Definition

oligodendrocytes form the myelin sheath around some nerve fibers in the CNS.

 

do not regenerate.

Term
gray matter
Definition
groups of neural cell bodies and their dendrites.
Term
white matter
Definition

bundles of parallel axons with their myelin sheaths

 

in the CNS, these are nerve tracts

in the PNS, these are called nerves

Term
resting membrane potential
Definition
the difference across the membrane of a resting cell
Term
depolarized
Definition

state in which membrane is permeable to Na+ ions for a brief period of time causing a reverse in charges inside and outside of the membrane

Term
action potential
Definition
nerve impulse
Term
synapse
Definition

nerve cell junction

Term
presynaptic membrane
Definition
The part of the cell membrane of an axon terminal that faces the cell membrane of the neuron or muscle fiber with which the axon terminal establishes a synapse.
Term
postsynaptic membrane
Definition
The surface of the cell on the opposite side of the synapse from the synaptic terminal of the stimulating neuron that contains receptor proteins and degradative enzymes for the neurotransmitter.
Term
common neurotransmitters
Definition
norepinephrine, acetylcholine, seratonin, dopamine, gamma-aminobutyric acid (GABA), glycine and endorphins.
Term
reflex
Definition
involuntary reactiotn in response to a stimulus applied to the periphery and transmitted to the CNS.
Term
reflex arc
Definition
basic functional unit of the nervous system and the smallest, simplest pathway capable of recieving a stimulus and yielding a response.
Term
converging circuit
Definition
two or more neurons that synapse with the same neuron
Term
diverging circuit
Definition
axon from one neuron divides and synapses with more than one neuron. this allows information transmitted in one neural pathway to diverge into two or more pathways.
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