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Flashcards in Neurophysiology Deck (62):
1

peripheral neuropathy

pain and dysesthesia
-loss of sensation or reflex;weakness
-fasciculations and paresthesia

2

mononeuropathy

involve isolated neurons
-trauma or pressure

3

radiculopathy

damage to nerve roots

4

polyneuropathy

metabolites, toxins, demyelinateing disease, chronic infections

can affect axon, myelin, or synapse

5

diabetic neuropathy

hyperglycemia is trigger
-pro-oxidative and pro-inflammatory
-PNS cells more susceptible
-predominantly axonal damage
-variable demyelination

6

resting membrane potential

-65

7

synaptic potential

slow, graded, local

8

action potential

brief, actively propagated and traveling

9

equilibrium

current of ion moving in and out of cell is equal
--determined by charge and concentration

10

establishment of RMP

inward Na
outward K

-closer to K - because it has greater permeability

maintained bt Na/K ATPase pump

11

capacitor

lipid bilayer
-stores charge on opposite sides

12

resistor

ion channels
-allow certain amount of ions to flow

13

conductance

flow of ion across membrane

14

resistance

opposite of conductance

15

depolarization

due to inward Na current

16

hyperpolarization

due to outward K current

17

voltage-gated Na channels

open - membrane depolarization
inactivation - closed and will not reopen
deinactivated or resting - after membrane repolarized, return to conformation that allows them to opened in response to depolarization

18

voltage gated K channels

open - slowly, response to depolarization
-do not inactivate
resting - after membrane repolarized

19

steps in AP

depolarization
-rising phase
-falling phase
-undershoot
-resting

20

temporal summation

multiple signal over time may reinforce eachother

21

spatial summation

multiples signals that are physically close may influence eachother

22

time constant

how long to reach final voltage
-depends on number of channels
-many open channels, lower time constant

23

length constant

distance required for current to decline

24

neuromuscular junction

unmyelinated at axon
-release of acetylcholine
-muscle fiber - ligand gated ion channels

25

muscle atrophy

due to loss of trophic effect on muscle

26

fibrillation or fasciculation

neurotransmitter loss from damaged axon or schwann cells

27

peripheral nerve disease

motor - muscle atrophy
autonomic nerves - sweating lost, dry, cracked skin

28

loss of efferent autonomics

lose sweating
dry cracked skin

29

loss of afferent autonomics

changes in sensation, pain

30

internodal segment

myelin between two nodes

31

saltatory conduction

AP - travels along internodal parts of axon
-speeds signal speed

32

nerve conduction studies

myelin damage - slow conduction
axon damage - failure of propagation, ectopic propagation, decreased SNAP amplitude

33

PNS regeneration

schwann cells dedifferentiate
-macrophage phagocytose
-anterograde degeneration (wallerian)
-retrograde signaling induces reorganization of soma (chromatolysis)
-regeneration - neurite sprouts guided by schwann cells until connection mae
-schwann cells redifferentiate

34

fibrous astrocytes

white matter
-long and thin processes

35

protoplasmic astrocytes

gray matter
-short and frilly processes

36

astrocytes

control brain ECF
-store all glycogen in brain
-limit K accumulation

37

membrane potential in brain

lower
-85

38

primary brain injury

at time of injury
-axonal injury, vascular injury, CN injury, contusion, laceration

39

secondary brain injury

within 12-24 hours
-swelling, infection, increased ICP, hypoxic injury

40

edema

glial cells - uptake of K, followed by Cl and water - swelling

41

generalized edema

increased total ICP
-increase arterial pressure

42

focal edema

displaces nearby structure

43

Sx of edema

headache, vomiting, altered consciousness, focal neuro problems

44

Tx of edema

hyperventilation - alkalosis induces vasoconstriction
osmolytes - mannitol

45

scar formation

astrocyte and microglia
-reactive gliosis - scar or plaque formation

46

neurotransmitter release

Ca induced

47

termination of signal

uptake or degradation

48

uptake to presynaptic cell

serotonin, dopamine, NE

49

neuropeptides

fast axonal transport

50

amines and amino acids

made in presynpatic cytoplasm

51

excitotoxicity

excessive accumulation of neurotransmitter in brain ECF

52

glutamate

inhibits Na/K ATPase

53

excitation

fast - ligand-gated ion channels
slow - GPCRs

54

EPSP

closer to threshold

55

IPSP

moves away from threshold

56

potentiation

repeated APs
-more neurotransmitter with each AP

57

depression

high frequency AP - depletion of vesicles
low frequency - intracellular Ca - induce phosphatase

58

memory

synapses physical site of memory storage

59

working memory

fleeting changes

60

long-term memory

sensitivity of synapse to past activity influences long-term effectiveness

61

long-term potentiation

increase amplitude of EPSPs

62

long term depression

decrease amplitude of EPSPs