CVS 2.1 - The Heart as a Pump Flashcards Preview

ESA 2 > CVS 2.1 - The Heart as a Pump > Flashcards

Flashcards in CVS 2.1 - The Heart as a Pump Deck (41):
1

In which system of circulation is pressure high and in which is low? Why is this important?

- Systemic circulation = high
- Pulmonary circulation = low

- Output must be equal

2

What is systole?

Contraction and ejection of blood from the ventricles

3

What is diastole?

Relaxation and filling of the ventricles

4

Describe the structure of cardiac muscle. How is its structure related to its function?

- Distinct cells that are interconnected electrically

- Electrical signals can pass through freely so that beating can be synchronised

5

Describe the length of action potentials in cardiac muscle. What happens as a result of an action potential here?

- AP = long and lasts for one contraction

- AP spreads from cell to cell which contract in response causing an increase in intracellular Ca2+

6

What is the function of valves in the heart?

Allow blood to flow in one direction by opening or closing depending on different pressures

7

Which valves separate atria from ventricles?

- Tricuspid valve (right)
- Mitral valve (left)

8

Which valves lead to output vessels?

- Pulmonary valve
- Aortic valve

9

Describe the pumping system of the heart

Two pumps acting in series

10

What is the function of the valve cusps?

- Allow blood flow when pushed open
- Prevent back flow of blood when pushed closed

11

Where do the mitral and tricuspid valves attach? What is the function of this?

- Chordae tendinae

- Attach to papillary muscles which prevent the inversion of valves during systole

12

How long does the AVN delay the action potential signal for?

- ~120 ms

13

What are the stages of the cardiac cycle? (7)

1) Atrial Contraction
2) Isovolumetric Contraction
3) Rapid Ejection
4) Reduced Ejection
5) Isovolumetric Relaxation
6) Rapid Filling
7) Reduced Filling

14

Describe the events of atrial contraction

- Pressure increases in the atria due to contraction

- Mitral and tricuspid valves are open

- Aortic and pulmonary valves are closed

15

Which wave on the Wigger curve represents atrial contraction?

A wave

16

Which ECG wave represents atrial contraction?

P wave

17

What does atrial contraction result in? What does this mean?

- End diastolic volume (~120ml)

- Maximum amount of blood the ventricles can hold

18

Why does atrial contraction only provide the final 10-20% of blood to the ventricle?

- Ventricles are already 80-90% full from the previous cardiac cycle

- Ventricles passively fill with blood when the valves are open

19

Describe the events of isovolumetric contraction

- Ventricular contraction begins which increases pressure

- Intraventricular pressure becomes HIGHER than aortic pressure

- There is NO CHANGE in ventricular volume

20

Describe the positions of the valves during isovolumetric contraction

- Mitral and tricuspid valves = closed

- Pulmonary and Aortic valves = closed

21

Which wave on the Wigger curve represents isovolumetric contraction?

- C wave (closing of mitral valve)

22

Which ECG wave represents isovolumetric contraction?

QRS complex

23

Describe the events of rapid ejection

- Begins when intraventricular pressure becomes HIGHER than aortic pressure

- Rapid decrease in ventricular volumer as blood is pushed through to the aorta

- Decrease in atrial pressure causes atria to be pushed down which also decreases ventricular volume

- Blood is still flowing into atria from venous return

24

Describe the position of the valves during rapid ejection

- Mitral and tricuspid valves = closed

- Aortic and Pulmonary valves = open

25

Which wave on the Wigger curve represents rapid ejection?

- X descent

26

Describe the events of reduced ejection

- Repolarisation of ventricles = decreased tension

- Gradual increase in atrial pressure due to venous return

27

Describe the position of the valves during reduced ejection

- Mitral and Tricuspid = closed

- Aortic and Pulmonary = Open

28

Which wave on the Wigger curve represents reduced ejection?

V Wave

29

Which ECG wave represents reduced ejection?

T wave

30

Describe the events of isovolumetric relaxation

- Rapid decrease in ventricular pressure

- Ventricular volume remains constant due to closed valves

- Intraventricular pressure becomes LOWER than aortic pressure

- Brief back flow of blood from aorta

31

What does isovolumetric relaxation result in? What is this?

- End Systolic Volume

- The volume of blood left in the ventricles

32

Describe the position of the valves during isovolumetric relaxation

- Mitral and Tricuspid = Closed

- Pulmonary and Aortic = Closed

33

Define stroke volume. How is it calculated?

- Amount of blood ejected in each cycle, from each ventricle

- End Diastolic Volume - End Systolic Volume

34

Describe the events of rapid filling

- Intraventricular pressure is LOWER than atrial pressure

- Causes mitral valve to open which decreases atrial pressure

- Volume in ventricle increases

35

Describe the position of the valves during rapid filling

- Mitral and Tricuspid valves = Open

- Pulmonary and Aortic valves = Closed

36

Which curve on the Wigger graph represents rapid filling?

Y Curve

37

Describe the events of reduced filling

- Rate of ventricular filling slows (diastasis)

- Ventricle reaches relaxed volume

38

Describe the position of the valves during reduced filling

- Mitral and Tricuspid valves = Open

- Pulmonary and Aortic valves = Closed

39

During which stages of the cardiac cycle can the S1, S2 and S3 sounds be heard respectively?

- S1 = Isovolumetric Contraction (LUB sound)

- S2 = Isovolumetric Relaxation (DUB sound)

- S3 = Rapid Filling (Unusual. Common in children/pathology)

40

What happens to make the S1 sound?

Closure of the mitral valve

41

What happens to make the S2 sound?

Closure of the aortic valve

Decks in ESA 2 Class (63):