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Flashcards in ch. 12 Deck (97)
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61

fx: myelinate axons
regulate interstitial environment around PNS neurons

FX PNS

62

2 types of neuroglial cells that myelinate axons

oligodendrocytes on CNS axons
schwann cells on PNS axons

63

how do the 2 types of neuroglial cells cover the axon

wrap themselves many times around the axon to form many layer along the length of an axon.
this forms lipid rich myelin sheath covering on outside of axon

64

small gaps in axon covering between cells

nodes of ranvier

65

axons with myelin sheath?

white matter

66

no myelin sheath

gray matter

67

why is it white matter

because of lipids

68

what causes gray matter

unmyelinated nerve fibers, cell bodies, and dendrites form gray matter in CNS

69

myelin coating in CNS demyelinate and forms hard scars that block the underlying neurons from transmitting messages- muscles no longer receive input from motor neurons-stops contracting-atrophy

multiple sclerosis

70

autoimmune

guiliain-barre syndrome

71

demyelination of peripheral nerves (extremity weakness-paralysis-problems breathing)

guiliain-barre syndrome

72

potential electrical difference across a cell membrane- cell membrane is electrically charged polarized

transmembrane potential

73

transmembrane potential in an undisturbed/resting cell

resting potential

74

the numerical value of the resting potential in a neuron

-70 millivolts in neurons

75

why is the numerical value of the resting potential in a neuron negative

inside of the cell membrane contains excess of negative ions compared with the outside

76

explain how the resting potential is maintained in a neuron

Sodium-potassium pumps move two potassium ions inside the cell as three sodium ions are pumped out to maintain the negatively-charged membrane inside the cell

77

shift of potential to become more positive

depolarization

78

what causes depolarization

causes from Na+ entering cell

79

restoring potential to normal resting potential

repolarizing

80

if potential is becoming more negative

hyperpolarizing

81

what causes hypolarizing

result from K+ leaving cell

82

when charge is going up

threshold

83

graded potential at opposite ends of the cell are linked by a what

action potential

84

junction between 2 neurons where nerve impulses travel across to the next neuron

the synapse

85

there is a charge across membrane

transmembrane potential

86

inside the membrane is more what

negative

87

outside the membrane is more what

positive

88

whatever is not is a resting state

refractory period

89

action potential is relayed from one location to another down an axon

propagation

90

which is faster continuous or saltatory and why

saltatory- not as many action potential and moves farther in distance quicker