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Physiology I Block 3 > Cardiology 7.6 > Flashcards

Cardiology 7.6 Flashcards

1
Q

inward current do what to cell

A

depolarize

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2
Q

outward current do what to cell

A

repolarize

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3
Q

calcium current is voltage gated channel but modulated by

A

ligand gated channels

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4
Q

as AP is depolarizing what happens to the voltage channels

A

have a voltage threshold

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5
Q

what does calcium current do for plateau phase of AP

A

stays open

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6
Q

if you express calcium current in nerve cell can make it look like

A

cardiac cell

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7
Q

9:37

A

helps maintain

triggers relese of calcium from SR (calcium induced calcium release)

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8
Q

without calcium release cardiac cell will not

A

contract

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9
Q

sodium channels stay inactivated throughout

A

most of AP

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10
Q

what accounts for refractory period

A

sodium channels inactivated

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11
Q

depol cell and if nothing else happened what would happen to membrane potential if no potassium channels?

A

just shutting off sodium channels does not cause repol. so it wouldn’t repol.

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12
Q

whether membrane potential is depolarizing or repolarizing depends on net

A

ionic current

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13
Q

if inward current and outward currents whether big or small, if they are equal and opposite, membrane potential will be

A

stable

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14
Q

during depol net current ha to be

A

inward

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15
Q

during repol net current has to be

A

outward

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16
Q

Ito

A

potassium current

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17
Q

Ito accounts for what

A

accounts for phase 1 of AP

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18
Q

what happens to rate of phase 1 if you block Ito

A

slower

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19
Q

Ik

A

potassium current

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20
Q

Ik1

A

potassium current

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21
Q

Ik1 accounts for what when open

A

resting potential

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22
Q

if you have resting potential cell has to have open ____ channels

A

potassium

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23
Q

what happens to Ik1 to help depol cell

A

closes

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24
Q

what happens to AP if you block Ik

A

AP would get longer

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25
Q

longer AP b/c of blocked Ik what time interval would increase

A

QT

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26
Q

long QT syndrome are prone to

A

particular arhythmia

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27
Q

antihistamine blocked an Ik and what did it do

A

caused death! b/c it blocked the Ik

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28
Q

all drugs have to be tested to see if they block

A

Ik

b/c of that histamine that blocked Ik channel and killed ppl

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29
Q

anti-arthmia in too high a dose can be pro-

A

arthymic

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30
Q

how does HR affect AP duration

A

when you increase HR, AP duration (and refractory period) they are inversely proportional

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31
Q

increase HR what happens to diastolic interval

A

decreased but is still preserved

32
Q

SA node and AV node are

A

pacemaker cells

33
Q

phase 4 of SA node

A

spontaneously depols and fires AP

34
Q

what don’t we see in SA node

A

the big sodium currents

calcium currents are smaller

35
Q

upstroke of SA node is generated by acrtivation of

A

Ica

calcium current

36
Q

If

A

“funny current”

sodium ion channel

37
Q

draw out currents of SA node

A

pg 83

38
Q

if you gave toxic dose of calcium channel blocker what will it do

A

block the Ica current and SA node will stop firing

39
Q

SA node pacemaker activity is elicited by small sodium current, opens when it repolarizies, inward current dpols cell and brings it to thrshold. calcium current helps dpol towards end. activation of calcium current generates upstroke.

A

.

40
Q

main way to regulate heart rate is by

A

autonomic nervous system

41
Q

how does epi and noepi increase HR

A

increase rate of diastolic depol

increase If and Ica

42
Q

block all beta receptors in heart and what happens to HR

A

wouldn’t go up

43
Q

how does acetylcholine decrease heart rate

A

slows rate of diastolic depol & hyperpol Vm
decrease If & Ica
increase Ik, Ach

44
Q

Ach does what to heart

A

slows rate of depol and hyperpolarizes cell so moves further away from calcium current threshold

45
Q

if you stimulate the vagus nerve you can stop what from firing

A

SA node

46
Q

stop vagus nerve, then after a few seconds what happens

A

heart starts firing again b/c another pacemaker takes over

47
Q

when pt has high or low HR it might not have anything to do with SA node but could be due to

A

autonomic input

48
Q

beta 1 blockers will block effect of

A

sympathetic tone on HR and will slow HR

49
Q

HR goes down with exercise due to

A

increased vagal tone

50
Q

when HR above 100 beats/min called

A

tachycardia

51
Q

if HR less than 60 Beats/min called

A

bradycardia

52
Q

sinus arhymia means

A

SA node is driving the heart

53
Q

gatekeeper b/w atria and ventricles

A

AV node

54
Q

normally AP cannot propegate across

A

CT barrier (see pg 87)

55
Q

wants conduction veloctiy reaches his bundles

A

it is very fast

56
Q

atrial systole and ventricular systole is delayed b/c

A

it cannot pss through the CT it is blockin AV node

57
Q

if ventricles are firing super fast what does AV node do

A

electrical filter, only allows certain ones through

58
Q

bypass track

A

AP can go through and bipass

59
Q

echo

A

10:07

60
Q

rentry

A

echo

61
Q

rentry is one of the most common causes of

A

arrhythmias

62
Q

heart cells are electrically connected to

A

gap junctions

63
Q

if gap junctions are closed

A

AP will not propagate

64
Q

what can close gap junctions

A

calcium inside cell too high

pH too low inside

65
Q

gap junction close would happen when

A

ischemia - oxygen falls CO2 goes up ATP down, lactic acid produced. calcium goes up and tends to close gap junctions

66
Q

how does AP propagate in cardiac

A

initial AP is what starts the whole thing, then the rest fire the same. individual cells connected by gap junctions

67
Q

bigger cells decrease intracellular resistance

A

faster conduction velocity

68
Q

in AV node cells are smaller and what is conduction velocity

A

much slower

69
Q

conduction velocity

A

if things in numerator go up it goes faster

if things in denominator go up it slows down

70
Q

if amplitude is bigger

A

goes faster

71
Q

small cells have ____ conduction velocity

A

slow

72
Q

if resistance increases

A

onduction velocity decreases

73
Q

if gap junction resistance (it’s closed down) then

A

conduction velocity slows

74
Q

if threshold voltage moves in positive direction what happens to conduction velocity

A

decreases

75
Q

lidocaine does what

A

sodium channel blocker
used at dentist
can also be used to help some arhythmias

76
Q

if you slowly depolarize a cell (like ventricular) sodium channels will directly from

A

ready to go closed state to inactivation state (hyperkalemia)

77
Q

if you depolarize cell to -50 mv the heart cell will not

A

fire AP

Physiology I Block 3 (14 decks)

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