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34 terms

Ch. 12 - cells

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central nervous system
brain and spinal cord
peripheral nervous system
cranial nerves and spinal nerves
afferent pathways
acending pathways, carry impulses toward CNS, part of PNS
efferent pathways
descending pathways, carry impulses away from CNS, part of PNS
somatic nervuos system
regulates voluntary motor control
autonomic nervous system
involuntary control of organ systems
neuron
primary nervous system cell
neuroglial cell
in CNS, provides structural support and nutrition
Schwann cell
in PNS, provides structuralsupport and nutrition
this cell type produces myelin sheeth
Schwann cell
this cell type conducts impulses to cell body
dendrite
myelin
insulator that allows ions to flow between segments rather than along entire length of membrane; increases velocity of ignal
saltatory conduction
Rapid transmission of a nerve impulse along an axon, resulting from the action potential jumping from one node of Ranvier to another, skipping the myelin-sheathed regions of membrane.
nodes of Ranvier
gaps between the myelin wrappings along the axon
divergence
ability of axonal branches to influence MANY neurons
convergence
branches of various neurons all influence a single neuron
unipolar neurons
have one process that branches shortly after leaving cell body
pseudounipolar neurons
have one process; the dendritic portion of each of these extends away from the CNS and axon projects into CNS
bipolar neurons
two distinct processes arising from cell body
multipolar neurons
most common type, have multiple processes capable of extensive branching
ex. unipolar neurons
neurons found in retina
ex. pseudounipolar neurons
sensory neurons in cranial and spinal nerves
ex. bipolar neurons
neurons connecting rod and cone cells of retina
ex. multipolar neurons
motor neurons
neurons: structural classifications
four types, based on number of processes extending from cell body
types of neurons
sensory, associational, motor
sensory neurons
afferent, mostly pseudounipolar (carry signals from peripheral sensory receptors to the CNS)
associational neurons
interneurons, multipolar (transmit signals from neuron to neuron)
motor neurons
efferent, multipolar (transmits signal away from CNS to an effector, such as skeletal muscle or organ
neuromuscular junction
end processes of motor neurons form in skeletal muscle
neuroglia
"nerve glue" - cells that support neurons of CNS
astrocytes
fill spaces between neurons and surround CNS blood vessels
oligodendroglia
deposit myelin within CNS, CNS equivalent of Schwann cells
microglia
phagocytosize debris in CNS