Session 2 - The Cardiac Cycle Flashcards

1
Q

what are resistance vessels?

A

vessels which can restrict blood flow to redirect blood

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2
Q

what are capacitance vessels

A

vessels which can hold a larger volume of blood without increasing in pressure

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3
Q

what are the 2 circulations?

A

pulmonary and systemic

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4
Q

what occurs during systole

A

contraction and ejection of blood from ventricles

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5
Q

what happens during diastole

A

relaxation and filling of ventricles

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6
Q

true or false; the action potentials in cardiac cells are relatively short

A

false

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7
Q

which is the only valve with 2 leaflets?

A

mitral valve

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8
Q

what are the mitral and tricuspid valve attached to

A

papillary muscles via the chordae tendineae

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9
Q

what do the papillary muscles and chordae tendineae do?

A

prevent inversion of the valves during systole due to the high pressure in the ventricles

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10
Q

what causes the opening and closing of valves

A

pressure difference on the 2 sides

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11
Q

which cells generate an action potential in the heart

A

specialised cardiac cells in the sinoatrial node

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12
Q

what is atrial systole

A

when the electrical activity spread over the atrial, causing them to contract

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13
Q

what happens when the electrical signal reaches the atrioventricular node

A

the signal is delayed to allow the atria to finish contracting and is spread down the septum and then through the ventricular myocardium causing the ventricles to contract

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14
Q

what are the purkinje fibres

A

fibres that send impulses to cells in the ventricles to cause them to contract

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15
Q

true or false; the excitation through the ventricles spreads through the endocardial to epicardial surface

A

true

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16
Q

what are the 7 stages in the cardiac cycle

A
  1. atrial
  2. isovolumetric contraction
  3. rapid ejection
  4. reduced ejection
  5. isovolumetric relaxtion
  6. rapid filling
  7. reduced filling
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17
Q

what happens to the length of diastole and systole when your heart rate increases

A

systole stays the same but diastole decreases

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18
Q

what side of the heart is a wiggers diagram plotted for? what would it look like if it was plotted for the other side?

A

Left. a diagram for the right would be similar but at lower pressures

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19
Q

what happens to atrial pressure in atrial contraction?

A

rises this gives the A wave

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20
Q

what wave is shown in an electrocardiogram during atrial contraction?

A

P wave which shows atrial depolarisation

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21
Q

what happens to the ventricle volume during atrial contraction

A

the final 10% of blood is added to the ventricles causing a small increase in volume. this gives the end diastolic volume

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22
Q

what is the main method of ventricle filling

A

passive filling during diastole

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23
Q

what is the end diastolic volume

A

when the ventricular volumes are at their maximum

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24
Q

what is the typical end diastolic volume value?

A

120 ml

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25
Q

what gives the first heart sound

A

closure of the mitral and tricuspid valves in isovolumetric contraction

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26
Q

why is phase 2 of the cardiac cycle known as isovolumetric contraction

A

there is no change in ventricular volume as all the valves are closed

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27
Q

why happens to the atrial pressure during isovolumetric contraction

A

there is a small inversion of the mitral valve when they close which increases the pressure slightly

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28
Q

what is seen on an electrocardiogram during isovolumetric contraction

A

the QRS complex is seen signifying ventricular depolarisation

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29
Q

which valves are open during isovolumetric contraction

A

none

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30
Q

what happens to ventricular volume during rapid ejection

A

decreases rapidly as the blood flows into the aorta

31
Q

which valves are open during rapid ejection

A

pulmonary and aortic valves

32
Q

what happens to atrial pressure during rapid ejection

A

initially decreases as the atrial base is pulled down as te ventricles contract. this is the X descent

33
Q

when does rapid ejection begin

A

when the ventricular pressure exceeds the pressure in the aorta causing the aortic valve to open. this is usually 80 mmHg

34
Q

what wave is seen in an electrocardiogram during reduced ejection

A

T wave due to ventricular repolarisation

35
Q

what happens to atrial pressure during reduced ejection

A

rises gradually due to venous return from the lungs. this is the V wave

36
Q

what happens to ventricular pressure during reduced ejection n

A

falls as repolarisation leads to a decline in tension

37
Q

which valves are open during reduced ejection

A

pulmonary and aortic valves

38
Q

which valves are open during isovolumetric relaxation

A

none

39
Q

which stage is the second heart sound in

A

isovolumetric relaxation

40
Q

what causes the second heart sound

A

the closing of the pulmonary and aortic valves

41
Q

what is the end systolic volume

A

the minimum volume of blood in the ventricles

42
Q

what happens to ventricular pressure during isovolumetric relaxation

A

declines rapidly

43
Q

what causes the dicrotic notch in aortic pressure

A

closure of the aortic valve

44
Q

what causes the closure of the aortic valve

A

when the ventricular pressure falls below aortic pressure giving a brief backflow of blood which closes the valve

45
Q

which valves are open in rapid filling

A

mitral and tricuspid valves

46
Q

what happens to the atrial pressure in in rapid filling

A

falls as the mitral valve opens giving the Y descent

47
Q

why does the mitral valve open during rapid filling

A

the pressure in the ventricles is below that of the atria

48
Q

in whom might a 3rd heart sound be heard in rapid filling

A

children

49
Q

what is diastasis

A

when the rate of filling of the ventricles slows down

50
Q

what is it called when the valves don’t open enough

A

stenosis

51
Q

what is it called when the valves don’t close all the way

A

regurgitation

52
Q

what are 3 causes of aortic valve stenosis

A
  1. degenerative (calcification or fibrosis)
  2. congenital (bicuspid form)
  3. chronic rheumatic fever
53
Q

what type of heart sound in heart in aortic stenosis

A

crescendo - decrescendo

54
Q

what happens to the red blood cells during aortic stenosis

A

they can become damaged (Microangiopathic haemolytic anaemia)

55
Q

what does aortic stenosis cause

A

left sided heart failure leading to syncope (fainting to lack of blood to CNS) and angina (lack of blood to cardiac cells). it also increase LV pressure leading to LV hypertrophy

56
Q

what causes aortic regurgitation

A

aortic root dilation and valvular damage

57
Q

what heart sound is heard during aortic valve regurgitation

A

descending murmur in diastole

58
Q

true of false; aortic regurgitation decreases stroke volume

A

false. blood flows back into the ventricles so theres more blood in the next cycle

59
Q

what happens to the diastolic and systolic pressures during aortic valve regurgitation

A

systolic pressure increases and diastolic pressure decreases

60
Q

true of false; patients have a bounding pulse in aortic regurgitation

A

true as the pulse pressure increases

61
Q

what does a bounding pulse result in

A

heading bobbing and Quinke’s sign

62
Q

what is Quinke’s sign

A

when the colour of the nail bed changes with the heart beat

63
Q

what heart sound is heard in mitral valve regurgitation

A

holosystolic murmur

64
Q

what normally prevent the prolapse of the mitral valve

A

chordae tendineae and papillary muscles

65
Q

what is myxomatous degeneration

A

the weakening of the mitral valve leading to prolapse

66
Q

what are the causes of mitral vlave regurgitation

A

damage to papillary muscles following a heart attack as these cells might die, left sided heart failure leading to LV dilation stretching the valve and rheumatic fever disrupting seal due to fibrosis

67
Q

true or false mitral valve regurgitation increases preload

A

true. As blood leaks back into the LA it means more blood will enter the LV in subsequent cycles

68
Q

what is the main cause of mitral valve stenosis

A

rheumatic fever

69
Q

where is there increased pressure during mitral valve stenosis?

A

left atrium

70
Q

what are the results of mitral valve stenosis

A
  1. atrial fibrillation due to stretching of muscle cells
  2. oesophagus compression due to dilation of the LA
  3. Pulmonary oedema (increased pressure in LA causes blood to back up into the lungs)
71
Q

why is there RV hypertrophy in mitral valve stenosis

A

increased pressure in the LA causes blood to back up in the lungs so its harder for the RV to force blood out

72
Q

what does atrial fibrillation during mitral valve stenosis cause

A

thrombus formation

73
Q

what does oesophagus compression in mitral valve stenosis cause

A

dysphagia (difficultly in swallowing)

74
Q

what is dyspnea

A

difficultly breathing