CVS 2 (Histology and Cardiac Cycle) Flashcards Preview

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Flashcards in CVS 2 (Histology and Cardiac Cycle) Deck (56)
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1
Q

Which is more permeable: a capillary or a post-capillary venule?

A

Post-capillary venule

2
Q

Arteries and veins often accompany each other. Which usually has the largest diameter?

A

Veins

3
Q

Why do the superficial veins of the legs have well-defined muscular walls, but other veins don’t?

A

To resist the distension which would be caused by gravity if the muscle wasn’t present.

4
Q

Which veins have well-defined muscular walls?

A

Superficial veins of the legs

5
Q

Define venae comitantes:

A

A pair of deep veins which accompany an artery, where all 3 vessels are wrapped in the same sheath.

6
Q

What is the importance of venae comitantes?

A

The pulsing of the accompanying artery promotes venous return.

7
Q

Name the 1st 3 arteries which branch from the aortic arch, in order from closest to heart:

A

1) Brachiocephalic artery
2) Left common carotid artery
3) Left subclavian artery

8
Q

Which 2 vessels feed into the right atria?

A

1) Superior vena cava

2) Inferior vena cava

9
Q

Which vessel takes blood away from the right ventricle?

A

Pulmonary trunk (immediately bifurcates into left and right pulmonary arteries)

10
Q

How many pulmonary veins feed into the heart, and which chamber do they feed into?

A

4 pulmonary arteries

Left atria

11
Q

Which vessel takes blood away from the left ventricle?

A

Ascending Aorta

12
Q

Name the valve which separates the left atria from the left ventricle:

A

Mitral valve

13
Q

Name the valve which separates the right atria from the right ventricle:

A

Tricuspid AV valve

14
Q

Describe the position and structure of the aortic semilunar valve:

A

Positioned between the left ventricle and the ascending aorta
Tricuspid

15
Q

Describe the position and structure of the pulmonary semilunar valve:

A

Positioned between the right ventricle and the pulmonary trunk
Tricuspid

16
Q

What is the approx. pressure in the left atria?

A

~ 8-10 mmHg

17
Q

What is the approx. pressure in the left ventricle (systole/diastole mmHg)?

A

~ 120 / 10 mmHg

18
Q

What is the approx. pressure in the aorta (systole/diastole mmHg)?

A

~ 120 / 80 mmHg

19
Q

What is the approx. pressure in the right atria?

A

~ 0-4 mmHg

20
Q

What is the approx. pressure in the right ventricle (systole/diastole mmHg)?

A

~ 25 / 4 mmHg

21
Q

What is the approx. pressure in the pulmonary artery (systole/diastole mmHg)?

A

~ 25 / 10 mmHg

22
Q

Define systole:

A

Contraction of the ventricle wall and ejection of blood into vessels

23
Q

Define diastole:

A

Relaxation of ventricle wall and filling of ventricles with blood

24
Q

What is the approx. stroke volume of the heart?

A

~ 70 ml/beat

25
Q

Define stroke volume:

A

Amount of blood ejected from the (left) ventricle per beat

26
Q

What is the approx. duration of a cardiac myocyte action potential?

A

~ 280 ms

27
Q

What property of cardiac myocytes ensures electrical stimulation across the myocardium?

A

Gap junctions within the intercalated discs

28
Q

Name the 4 valves in the heart:

A

1) Tricuspid AV valve
2) Mitral valve
3) Pulmonary (semilunar) valve
4) Aortic (semilunar) valve

29
Q

What connects the cusps of the heart valves to the papillary muscles?

A

Chordae tendineae

30
Q

What is the essential role of the chordae tendineae and the papillary muscles?

A

To prevent inversion of the AV valves during systole

31
Q

Define chordae tendineae:

A

Strong fibrous cords made by chordal fibroblasts, which connect the cusps of the AV valves to the papillary muscles.

32
Q

How long is the cardiac action potential delayed for when it reaches the AV node?

A

~ 120 ms

33
Q

From the AV node, what is the passage of AP conduction causes ventricle systole?

A
  • Down Bundle of His

- Up Purkinje fibres

34
Q

Name the 7 phases of the cardiac cycle, starting with 1) Atrial contraction :

A

1) Atrial contraction
2) Isovolumetric contraction
3) Rapid ejection
4) Reduced ejection
5) Isovolumetric relaxation
6) Rapid filling
7) Reduced filling

35
Q

What is the average time of 1 heart beat at rest?

A

~ 0.9 s

36
Q

What is the typical End-Diastolic Volume (EDV)?

A

~ 120 ml

37
Q

What happens first during a heart beat: P wave of ECG or A wave of atrial pressure? Why?

A

P wave, as it indicates atrial depolarisation, which then causes atrial contraction, increasing the atrial pressure, producing the A wave.

38
Q

What % of ventricular filling is accounted for by atrial contraction?

A

~ 10%

39
Q

How does the body still function during atrial fibrillation?

A

The ventricles are 90% filled via gravity when the valves open, so atrial contraction is not necessary for blood to move around the heart, to be pumped around the body.

40
Q

What phase of the cardiac cycle occurs as S1 is heard?

A

Isovolumetric contraction

41
Q

What is the sound S1 caused by?

A

Closing of the mitral and tricuspid AV valves

42
Q

What causes the mitral valve to close?

A

Ventricular pressure exceeds atrial pressure

43
Q

How does the closing of the mitral valve affect the atrial pressure?

A

Causes slight increase of atrial pressure (C wave)

44
Q

During what phase of the cardiac cycle does the QRS complex of the ECG occur?

A

2: Isovolumetric contraction

45
Q

What part of the ECG corresponds to ventricular depolarisation?

A

QRS complex

46
Q

Just after S1, which valves open?

A

Aortic semilunar valve

Pulmonary semilunar valve

47
Q

Describe the immediate change in ventricular volume after S1:

A

Ventricular volume decreases from ~120 ml to ~40ml

48
Q

Which wave of the ECG corresponds to ventricular repolarisation?

A

T wave

49
Q

What causes the aortic valve to close?

A

Pressure in the aorta is higher than the pressure in the left ventricle, and slight backflow of blood

50
Q

What is the ‘dicrotic notch’?

A

Small downward deflection of aortic pressure caused by closure of semilunar valves

51
Q

What is the typical End-Systolic Volume (ESV)?

A

~ 40 ml

52
Q

Define stroke volume:

A

Amount of blood ejected by left ventricle during one contraction

53
Q

What is the sound S2 caused by?

A

Closing of the aortic and pulmonary semi-lunar valves

54
Q

What is meant by the X- and Y-descent, in regards to atrial pressure?

A
X-descent = Fall in atrial pressure during ventricular contraction
Y-descent = Fall in atrial pressure after opening of the mitral valve
55
Q

What causes the mitral valve to open?

A

Atrial pressure is greater than ventricular pressure (in left heart)

56
Q

In what situation is the sound S3 considered normal?

A

In children