Neurophysiology

Question 1

peripheral neuropathy

Answer 1

pain and dysesthesia

• loss of sensation or reflex;weakness
• fasciculations and paresthesia

Question 2

mononeuropathy

Answer 2

involve isolated neurons

-trauma or pressure

Question 3

radiculopathy

Answer 3

damage to nerve roots

Question 4

polyneuropathy

Answer 4

metabolites, toxins, demyelinateing disease, chronic infections

can affect axon, myelin, or synapse

Question 5

diabetic neuropathy

Answer 5

hyperglycemia is trigger

• pro-oxidative and pro-inflammatory
• PNS cells more susceptible
• predominantly axonal damage
• variable demyelination

Question 6

resting membrane potential

Answer 6

-65

Question 7

synaptic potential

Answer 7

slow, graded, local

Question 8

action potential

Answer 8

brief, actively propagated and traveling

Question 9

equilibrium

Answer 9

current of ion moving in and out of cell is equal

–determined by charge and concentration

Question 10

establishment of RMP

Answer 10

inward Na
outward K

-closer to K - because it has greater permeability

maintained bt Na/K ATPase pump

Question 11

capacitor

Answer 11

lipid bilayer

-stores charge on opposite sides

Question 12

resistor

Answer 12

ion channels

-allow certain amount of ions to flow

Question 13

conductance

Answer 13

flow of ion across membrane

Question 14

resistance

Answer 14

opposite of conductance

Question 15

depolarization

Answer 15

due to inward Na current

Question 16

hyperpolarization

Answer 16

due to outward K current

Question 17

voltage-gated Na channels

Answer 17

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

Question 18

voltage gated K channels

Answer 18

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

Question 19

steps in AP

Answer 19

depolarization

• rising phase
• falling phase
• undershoot
• resting

Question 20

temporal summation

Answer 20

multiple signal over time may reinforce eachother

Question 21

spatial summation

Answer 21

multiples signals that are physically close may influence eachother

Question 22

time constant

Answer 22

how long to reach final voltage

• depends on number of channels
• many open channels, lower time constant

Question 23

length constant

Answer 23

distance required for current to decline

Question 24

neuromuscular junction

Answer 24

unmyelinated at axon

• release of acetylcholine
• muscle fiber - ligand gated ion channels

Question 25

muscle atrophy

Answer 25

due to loss of trophic effect on muscle

Question 26

fibrillation or fasciculation

Answer 26

neurotransmitter loss from damaged axon or schwann cells

Question 27

peripheral nerve disease

Answer 27

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

Question 28

loss of efferent autonomics

Answer 28

lose sweating | dry cracked skin

Question 29

loss of afferent autonomics

Answer 29

changes in sensation, pain

Question 30

internodal segment

Answer 30

myelin between two nodes

Question 31

saltatory conduction

Answer 31

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

Question 32

nerve conduction studies

Answer 32

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

Question 33

PNS regeneration

Answer 33

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

Question 34

fibrous astrocytes

Answer 34

white matter | -long and thin processes

Question 35

protoplasmic astrocytes

Answer 35

gray matter | -short and frilly processes

Question 36

astrocytes

Answer 36

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

Question 37

membrane potential in brain

Answer 37

lower | -85

Question 38

primary brain injury

Answer 38

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

Question 39

secondary brain injury

Answer 39

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

Question 40

edema

Answer 40

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

Question 41

generalized edema

Answer 41

increased total ICP | -increase arterial pressure

Question 42

focal edema

Answer 42

displaces nearby structure

Question 43

Sx of edema

Answer 43

headache, vomiting, altered consciousness, focal neuro problems

Question 44

Tx of edema

Answer 44

hyperventilation - alkalosis induces vasoconstriction | osmolytes - mannitol

Question 45

scar formation

Answer 45

astrocyte and microglia | -reactive gliosis - scar or plaque formation

Question 46

neurotransmitter release

Answer 46

Ca induced

Question 47

termination of signal

Answer 47

uptake or degradation

Question 48

uptake to presynaptic cell

Answer 48

serotonin, dopamine, NE

Question 49

neuropeptides

Answer 49

fast axonal transport

Question 50

amines and amino acids

Answer 50

made in presynpatic cytoplasm

Question 51

excitotoxicity

Answer 51

excessive accumulation of neurotransmitter in brain ECF

Question 52

glutamate

Answer 52

inhibits Na/K ATPase

Question 53

excitation

Answer 53

fast - ligand-gated ion channels | slow - GPCRs

Question 54

EPSP

Answer 54

closer to threshold

Question 55

IPSP

Answer 55

moves away from threshold

Question 56

potentiation

Answer 56

repeated APs | -more neurotransmitter with each AP

Question 57

depression

Answer 57

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

Question 58

memory

Answer 58

synapses physical site of memory storage

Question 59

working memory

Answer 59

fleeting changes

Question 60

long-term memory

Answer 60

sensitivity of synapse to past activity influences long-term effectiveness

Question 61

long-term potentiation

Answer 61

increase amplitude of EPSPs

Question 62

long term depression

Answer 62

decrease amplitude of EPSPs