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Physio > Cardio Lec 4 > Flashcards

Cardio Lec 4 Flashcards

1
Q

Normal heart sounds

A

s1, s2

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2
Q

s1 due to

A

av valve closing (ventricular systole)

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3
Q

s2 due to

A

semilunar valve closing (ventricular diastole)

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4
Q

Heart murmurs

A

abnormal heart sounds; most often when valve isn’t closing properly so blood is regurgitating due to back flow

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5
Q

When would you hear the murmur

A

when valve should be closed

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6
Q

During which phase would a murmur due to mitral valve regurgitation be heard most clearly?

A

during ventricular contraction

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7
Q

Incompetent valves refers to

A

improper closure (heard as a murmur)

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8
Q

Incompetent valves is due to

A

damage to papillary muscles or chordae tend.

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9
Q

Does cardiac muscle beats w/o help on NS?

A

yes

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10
Q

2 types of cells in myocardium

A

nodal cells & contractile cells

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11
Q

Nodal cells aka

A

pacemaker cells

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12
Q

T/F Nodal cells have unstable resting membrane potentials

A

T (have to fire spontaneously/don’t rely on a signal)

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13
Q

What allows heart to beat on own & how

A

pacemaker cells; nodal cells spontaneously depolarize –> fire an action potential –> send wave to contractile cells –> cause them to depolarize to threshold –> get them to fire action potentials –> heart muscle shortens & contracts

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14
Q

Myocardium connected via

A

gap junctions

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15
Q

How does wave spread thru heart as a SINGLE UNIT

A

by all cells being coupled to one another

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16
Q

Atria & ventricles separated via

A

fibrous skeleton that insulates electrical activity

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17
Q

Impulse that starts cycle originates in the

A

atria near SVC thru SA node aka pacemaker

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18
Q

Why is the SA node the pacemaker?

A

bc it fires more frequently than other areas

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19
Q

Do nodal cells contract?

A

no; they send electrical impulses to contractile cells

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20
Q

T/F: Nodal cells depolarize RAPIDLY on their own

A

F; SLOWLY

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21
Q

Pacemaker potential refers to

A

rate of rise to threshold

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22
Q

Funny current/Na channel opens when ___; other ion channels open when ___

A

membrane potential is most negative; most positive

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23
Q

Describe the action potential prod. by nodal cells/ pacemaker

A

(before threshold) Na channel opens @ -60 (its most negative) -> some depolarization -> causes transient Ca channel to open -> allows Ca & Na to enter -> 2 channels stay open until threshold -> @ threshold, voltage gated Ca channels open -> other 2 channels shut off -> membrane potential RAPIDLY depolarized -> @ peak, all (+) channels close -> K channels open -> cell repolarizes back to -60 -> funny current opens (little depolarization) -> causes t-type Ca channel open -> the 2 depolarize cell to threshold -> cause voltage gated Ca channels to open -> depolarize to peak -> all shut -> K channels open -> start over & over

24
Q

What dictates the HR?

A

rate/ how FREQUENTLY action potentials occur

25
Q

What would happen if you have a drug that causes channels not to open as fully?

A

take longer to depolarize –> hr slow down

26
Q

When the cell is firing its action potential that wave of depolarization spreads to

A

the adjacent cells via gap junctions

27
Q

What causes the myocytes to depolarize to threshold?

A

the spread to the adjacent cells via gap junctions

28
Q

Pacemaker potential/rise to threshold aka

A

phase 4

29
Q

Anything that increases slope of phase 4 will

A

increase hr

30
Q

Anything that decreases slope of phase 4 will

A

decrease hr

31
Q

Substances that increase slope of phase 4

A

Epi, norepi (bind to beta1 rs & make it QUICKER to get to threshold)

32
Q

Substance that decrease slope of phase 4

A

ACH (makes it take LONGER to get to threshold)

33
Q

How do substances binding to beta1 rs increase hr?

A

increase prod. of cAMP which causes Ca channels & funny current to open -> depolarize faster by bringing more + ions in

34
Q

How does Ach decrease hr?

A

closes na & ca channels, opens k channels

35
Q

If Ach given in a high enough does it will

A

stop the heart as a result of closing of channels

36
Q

Which would be expected to result in a reduction in hr?

A

opening of k channels

37
Q

In pacemaker cells, what ion channels open most dramatically once threshold voltage is reached?

A

calcium channels

38
Q

Ectopic foci/pacemaker refers to

A

any area other than SA node that is pacing the heart

39
Q

T/F: The SA node is the only nodal area w/ ability to spontaneously depolarize on its own

A

F; all nodal areas have the ability BUT DO SO LESS FREQUENTLY

40
Q

T/F: If SA node isn’t working properly, AV node can take over & pace the heart

A

T but hr would be slower (50-60bpm)

41
Q

If AV node blocked

A

Perkinje fibers can take over & pace ventricles but firing rate rlly infrequent; person would have hr: 30bpm -> person needs pacemaker

42
Q

If area other than SA node or any nodal area is pacing the heart, hr would be

A

higher

43
Q

What is required for muscle shortening/contraction?

A

calcium

44
Q

Myocardial action potentials initiated by

A

impulses from pacemaker cells

45
Q

Ventricular myocyte action potential

A

cell at RMP (-90 mv) -> depolarization coming from nodal/pacemaker cells -> myocytes to threshold causes na channel to open -> na rushes in & RAPID depolarization -> na channels shut at peak -> k (out) & ca channels open (ca in) -> plateau phase -> ca channels shut -> k channels stay open -> cell re-polarizes

46
Q

Cannot get contraction until __ because

A

plateau phase bc ca must be present

47
Q

When myocytes fire action potentials it causes

A

myocytes to contract based on ca coming in

48
Q

Arrythmias/Disrrythmias

A

abnormal rhythms

49
Q

What do Na, beta, K, & Ca channel blockers do

A

slow hr

50
Q

Cardiac conduction system

A

SA node signals atria to contract -> signal to AV node (slowly to allow ventricles to fill) -> thru bundle of his -> down bundle branches -> to perkinje fibers (quickly) -> cause ventricles to contract

51
Q

Cardiac conduction system seen thru

A

ekg

52
Q

Only way for signal to get from atria -> ventricle is thru

A

av node

53
Q

Excitation contraction coupling refers to

A

how the myocyte action potential is coupled to the actual contraction of the myocyte

54
Q

What causes the SR to release its calcium

A

calcium coming in when the action potential fires in the ventricular myocytes & voltage gated channels open (calcium induced calcium release)

55
Q

Initial calcium comes from

A

extracellular sources via VGCCs during plateau phase

56
Q

Extracellular calcium triggers

A

release of further intracellular calcium from SR -> causes contraction

Physio (14 decks)

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