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30 Cards in this Set
- Front
- Back
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Nervous System |
master controlling and communicating system of the body sensory input integration motor output |
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afferent
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sensory nerves |
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efferent |
motor nerves |
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neurons |
excitable cells that transmit electrical signals |
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supporting cells (neuroglia) |
cells that surround and wrap neurons |
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Neurons (nerve cells) |
longevity, lack ability to divide/reproduce, acons in periphery; cell bodies in brain and spinal cord, high metabolic rate, require constant O2 and glucose CNS can only metabolize sugar |
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Cell body (soma) |
in brain and spinal cord |
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dendrites |
short branches from soma, feelers that communicate with nearby cells |
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axon |
long extension; found in periphery, feelers at end, sends nerve impulses |
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synapse |
jct between axons and other structures, axons communicate everywhere |
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astrocytes |
(CNS) structure and repair largest, most abundant, sling to bv, axons, form blood brain barrier limits damage |
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schwann cells |
(PNS) forms myelin surrounds axons of PNS, form myelin sheath protection, insulation, regeneration of nerve fibers |
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myelin sheath |
white, fatty covering that increases the speed of nerve impulse |
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nodes of ranvier |
gaps in myelin |
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CNS gray matter |
unmyelinated |
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CNS white matter |
myelinated |
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PNS |
myelinated
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afferent |
dont have long axons |
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interneurons (association neurons) |
lie in b/t sensory and motor neurons site of integration 99% of neurons |
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graded potentials |
generated from any stimulus intensity differs based on amount of stimulus effects are local no refractory period occurs in most cell membranes |
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action potentials |
stimulus must reach threshold to generate always same intensity widespread effects refractory period occurs only in excitable membranes |
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refractory period |
period of time from initial AP production to stabilized RMP |
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absolute refractory period |
time from opening of Na+ gates to closing of Na+ gates membrane not responsive to additional stimulus ensures each AP is separate |
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relative refractory period |
follows absolute RP, from Na+ gates closing to RMP threshold for producing APs is increased more APs only produced with very large stimulus |
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Effect of neurotransmitter |
Depends on: amount released and amount of time it is bound to receptors |
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EPSP (excitatory post-synaptic potential) |
crosses synapse, depolarizes membrane binds to Na+ channel |
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IPSP (inhibitory post-synaptic potential) |
crosses synapse and binds to K+ channel to inhibit (hyperpolarize membrane) dopamine |
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Neurotransmitters |
chemicals that act as messengers in the nervous system effects can be excitatory, inhibitory, or both act directly or inhibit function only with specific receptors |
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cholinergic |
fibers that release ACh |
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adrenergic |
fibers that release norephinephrine (NE) |
