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HUBS192 > HEART PHYSIOLOGY I > Flashcards

HEART PHYSIOLOGY I Flashcards

1
Q

what does it mean by saying the heart is 2 pumps that lie ‘in series’?

A
  • equal blood flow from all organs –> right atrium –> right ventricle –> lungs –> left atrium –> left ventricle –> all organs –> back to heart as a closed cycle
  • right and left pumps contract simultaneously
  • atria contracts first, ventricles contract second
  • valves open/close to direct blood
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2
Q

which circuit has a lower pressure?

A

pulmonary circuit has lower pressure than systemic (however same bloodflow)

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3
Q

how does the circulatory system modulate to fix the different in pressure but same bloodflow require in the 2 circuits?

A

pulmonary circuit has lower resistance

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4
Q

what is the y-axis in the blood pressure trace?

A

arterial pressure (mmHg)

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5
Q

what is the x-axis of the blood pressure trace?

A

time (s)

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6
Q

which phase is longer in a heart cycle, diastole or systole?

A

diastole

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7
Q

what is the highest point and lowest point of the blood pressure trace?

A
  • highest point = systolic pressure
  • lowest point = diastolic pressure
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8
Q

what is the pulse and the mean pressure of a blood pressure cycle?

A
  • pulse pressure = difference between highest and lowest points
  • mean pressure = average across the full cycle
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9
Q

what is high blood pressure called?

A

hypertension

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10
Q

what is low blood pressure called?

A

hypotension

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11
Q

what is a complication of hypotension?

A

syncope - fainting

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12
Q

what stimulates the cardiomyocyte contraction?

A

an increase in [Ca2+] and released in sarcoplasmic reticulum

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13
Q

what does calcium release mean?

A

myosin can bind into actin to form cross-bridges –> myosin pulls actin to shorten sarcomere and generate force

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14
Q

what happen to myocyte during each heartbeat?

A

every myocyte activated during each heart beat

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15
Q

how can we increase force of contraction?

A
  • increase of cytosolic Ca2+ level
  • increase the number of cross-bridge formed (since extent of cross-bridges formed is not maximised at rest)
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16
Q

during cardiac relaxation, how is cross-bridge release?

A
  • decrease in cytosolic Ca2+ lvl –> Ca2+ pumped back into SR
  • ATP binds to myosin
  • all cardiac myocytes relax each beat
17
Q

how does a contraction of 1 cardiomyocyte would help also contract the next?

A
  • cardiac cells are connected by intercalated discs
  • cardiomyotyes are also connected by gap junction which directly connects the cytoplasm –> current moves between adjacent cells
18
Q

define diastole and systole?

A
  • diastole is the relaxation phase associated with falling ventricular pressure and takes up 2/3 of the cardiac cycle
  • systole is the contraction phase associated with rising ventricular cycle and takes up 1/3 of the cardiac cycle
19
Q

what are the 5 main stages of a cardiac cycle?

A

1/ ventricular filling
2/ atrial contraction
3/ isovolumetric contraction
4/ ventricular ejection
5/ isovolumetric relaxation
- back to ventricular filling

20
Q

this is a reminder to learn the cardiac cycle and put it all in together as well as associate the stages with diastole, systole and ECG (from lecture 8 and 9)

A
21
Q

what is ECG?

A

waveform produced from the electrical events activity of the heart

22
Q

what are the main waves/complex waves of an ECG diagram?

A
  • P wave
  • QRS complex
  • T wave
23
Q

what cause P wave?

A

atrial depolarisation (AP starts at SA node depolarise the atria)

24
Q

what happens at QRS complex?

A

ventricular depolarisation + atrial repolarisation

25
Q

what cause T wave?

A

ventricular repolarisation

26
Q

compare the electrical and contractile cells of the heart?

A
  • electrical: ‘pale’ striated appearance with low actin and myosin, takes up 1% of the heart’s cell
  • contractile: striated appearance with high actin and myosin, takes up 99% of the heart’s cell
27
Q

how does action potential propagate along the surface membrane of electrical and contractile cells?

A
  • intercalated discs connect most cells of the heart
  • gap junctions between electrical and contractile cells, as well as between contractile cells with each other –> allow current flow –> functional syncytium
28
Q

what does it mean by saying functional syncytium?

A

millions of cardiac cells to behave as one

29
Q

what are the 6 associated structures in the conduction pathway

A
  • SA node
  • interatrial bundle
  • Av node
  • internodal bundles
  • av bundle –> left and right branch of the av bundle
  • purkinje fibres
30
Q

this is a reminder to learn the excitation and conduction pathway of the heart (from lecture 9)

A
31
Q

what does SA node do?

A

emit signal that instruct the heart to beat

32
Q

why does AV node delay the impulse

A

allow atria to contract and pump blood into ventricle then relax and allow ventricle to contract

33
Q

why does conduction signal travel down to the bottom of the heart and then back up the ventricular walls?

A
  • efficient pump of bloodflow
  • exit routes of the blood is at base of heart –> pump to apex and pump up from the bottom
34
Q

name the 6 stages of excitation

A

1/ atrial depolarization, initiated by SA node –> cause P wave
2/ atrial depolarization completed, impulse delayed at AV node
3/ ventricular depolarization begins at apex –> cause QRS complex, at the same time atrial repolarization occurs
4/ ventricular depolarization complete
5/ ventricular repolarization begins at apex –> cause T wave
6/ ventricular repolariztion complete

35
Q

this is a reminder to learn the whole diagram on lecture 9 and try to explain it all in one, as well as define the heart event during lubb and dupp sound

A
36
Q

what structure is also known as the pacemaker of the heart?

A

SA node

37
Q

what directly stimulate function at purkinje fibres?

A

sympathetic cardiac nerves

HUBS192 (23 decks)

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