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Physiology of Disease > Exam 3- CV phys > Flashcards

Exam 3- CV phys Flashcards

1
Q

The heart’s ability to trigger its own contractions is called

A

autorhythmicity

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2
Q

autorhythmicity occurs because

A

the plasma membrane in cardiac pacemaker cells has reduced permeability to potassium ions but still allows sodium and calcium ions to slowly leak into the cells

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3
Q

depolarization causes voltage gated sodium channels in the cell membrane to open
this increases the flow of sodium into the cell

A

Phase 0

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4
Q

open sodium channels begin to inactivate

at the same time voltage-gated potassium channels close and voltage gated calcium channels open

A

Phase 1

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5
Q

potassium channels are closed
Long lasting L calcium channels stay open
lasts about .2 sec

A

Phase 2

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6
Q

a second set of potassium channels open allowing a significant amount of potassium to flow out of the cell
Calcium channels close

A

Phase 3

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7
Q

all voltage gated channel are closed

A

Phase 4

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8
Q

the reason tetanus occurs in skeletal muscle

A

sk muscle has a relatively short absolute refractory period

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9
Q

which is true of the cardiac myocyte action potential

A

it is longer than skeletal muscle cell action potential

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10
Q

the total cardiac action potential lasts

A

250-300 milliseconds

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11
Q

the period of time when cardiac muscle is incapable of reacting to any stimulus is

A

absolute refractory period

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12
Q

when you increased the frequency of stimulation the amplitude of the ventricular systole wave

A

did not change

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13
Q

When you delivered 20 stimuli/sec to the heart you saw

A

neither wave summation nor tetanus

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14
Q

an extrasystole is also a(n)

A

extra ventricular contraction

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15
Q

which contributes to the inability of the cardiac muscle to be tetanized

A

the long refractory period of the cardiac action potential

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16
Q

the amplitude of the ventricular systole did not change with the more frequent stimulation because

A

a new contraction could not begin until the relaxation phase

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17
Q

why is it important that cardiac muscle NOT reach tetanus?

A

the heart must relax fully to allow blood to enter

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18
Q

why is it only possible to induce an extrasystole during relaxation?

A

prior to relaxation the heart is in its absolute refractory period

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19
Q

explain why wave summation and tetanus are not possible in cardiac muscle

A

Cardiac muscle has a long plateau phase with a long associated absolute refractory period. A contraction can not begin until the ARF has ended-until relaxation. So wave summation and tetanus are impossible, treppe though, is possible

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20
Q

At rest both the SNS and PNS are working but the ______branch is more active

A

PNS

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21
Q

the _________nerve carries the parasympathetic signal to the heart

A

vagus

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22
Q

select the 2 factors that contribute to vagal escape

A

initiation of a rhythm by purkinje fibers

sympathetic reflexes

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23
Q

according to the introduction of activity 2 PEX 6 in the absence of parasympathetic stimulation , sympathetic stimulation, and hormonal controls, the SA node generates action potentials _____times per minute

A

100

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24
Q

When you applied multiple stimuli to the heart by indirectly stimulating the vagus nerve

A

the heart rate decreased

25
Q

After vagal nerve stimulation in activity 6 we saw vagal escape this was

A

he response that resumed the normal heart rate after multiple vagal nerve stimulation

26
Q

In the absence of neural and hormonal influences the SA node generates action potentials at a predetermined frequency . The resting HR is approximately 30 bpm lower. This suggests that

A

the parasympathetic system has more control over the resting HR

27
Q

If the vagus nerve was cut how you would expect the HR to change

A

without vagal stimulation you would expect the resting HR to be closer to 100

28
Q

humans are _____ which means that the human body maintains an internal body temperature within 35.8-38.2 degrees C range even though the external temperature is changing

A

homeothermic

29
Q

when you decreased the temperature of the ringer’s solution the frog heart rate

A

decreased

30
Q

you would expect the Heart rate of a person with a temperature of 100.4F=38C to be

A

increased compared to someone with a temperature of 37C

31
Q

if the frog heart was in distilled water and not in ringer’s solution

A

spontaneous cardiac action potentials would not develop

32
Q

norepinephrine and epinephrine increase the frequency of action potentials in the heart by binding to ____adrenergic receptors embedded in the plasma membrane

A

beta 1

33
Q

“Working through a _______2nd messenger mechanism, binding of the ligand (NE) opens sodium and calcium channels, increasing the rate of depolarization and shortening the period or repolarization”

A

cAMP

34
Q

agonist

A

produces the same response as the initial neurotransmitter of hormone

35
Q

antagonist

A

blocks the effect of the initial neurotransmitter or hormone

36
Q

Pilocarpine is an acetylcholine agonist that you applied to the frog heart in activty 4

this lead to a(n)

A

decrease in HR

37
Q

Atropine is an acetylcholine antagonist that you applied to the frog heart in activity 4
this lead to a(n)

A

increase in HR

38
Q

uses for calcium channel blockers are

A

treat hypertension

treat abnormal HRs

39
Q

greater concentration outside the resting cell

A

Ca2+, Cl-, Na+

40
Q

greater concentration inside the resting cell

A

K+

41
Q

effect of digitalis on the heart

A

decrease the HR, it also strengthens the contraction force to increase Stroke volume

42
Q

Phase 0 rapid depolarization

A

Na+ enters

43
Q

Phase 1 small repolarization

A

decrease in Na+ movement

44
Q

Phase 2 plateau

A

K+ movement out decreases Ca2+ enters the cell

45
Q

phase 3 repolarization

A

K+ leaves the cell Ca2+ movement decreases

46
Q

Phase 4 resting potential

A

K+ moves out little sodium or Ca2+ moves in

47
Q

the effect of increasing Na+ outside the heart was

A

negative chronotrope and negative inotrope

48
Q

A calcium channel blocker such as verapamil is a

A

negative chronotrope and negative inotrope

49
Q

pilocarpine is an acetylcholine agonist. Besides its effect on the heart
select three other possible responses

A

increase perspiration
increase GI activity- loose stool
contract the pupil

50
Q

digitalis is

A

positive inotrope

51
Q

the effect of increasing Ca2+ outside the heart was

A

positive chronotrope and positive inotrope

52
Q

hyperkalemia is expected to

A

decrease HR

53
Q

hypoxia, or worse anoxia, to cells results in cell death.

When there is decreased blood flow to cardiac cells this leads to cardiac cell death. When cells die the empty their contents. Remember, there is more potassium inside a cell then outside. Thus the microenvironment around a recently killed cell may be high in potassium. How might this affect the resting membrane potential of the still viable neighbor cells?

A

the hyperkalemia may decrease the resting membrane potential decreasing the strength of their contraction

54
Q

the addition of most ions on the frog heart lead to

A

an erratic HR

55
Q

affect of calcium channel blockers on smooth muscle found in blood vessels is to

A

decrease entry of calcium and thus lower vasomotor tone and vasodilate, decrease BP

56
Q

the phase of the cardiomyocyte action potential when calcium channels are open and potassium channels are closed is called the

A

plateau phase

57
Q

the initial effect of hyperkalemia is as

A

negative inotrope and negative chronotrope

58
Q

ion with the most profound change on the heart rate was

A

K+

Physiology of Disease (8 decks)

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