CVS - The Heart As A Pump Flashcards Preview

CJ: UoL Medicine Semester Two (ESA2) > CVS - The Heart As A Pump > Flashcards

Flashcards in CVS - The Heart As A Pump Deck (34):
1

What is the difference between resistance and capacitance vessels?

Resistance vessels - restrict blood flow to drive supply to hard to perfuse areas of the body, usually arteries.

Capacitance vessels - enable system to vary amount of blood pumped around body, usually veins.

2

Which has the higher pressure - the systemic or pulmonary circulation?

Systemic circulation has high, while pulmonary has low.

3

What is systole?

When the heart contracts and ejects blood from the ventricles

4

What is diastole?

When the heart relaxes and the ventricles fill.

5

What is the rough amount of blood pumped by each ventricle per beat?

About 70 ml

6

Is a cardiac action potential relatively long or short?

Relatively long - lasts for duration of a single contraction of heart (around 280ms)

7

Which valve regulates flow from left atrium to left ventricle?

Mitral valve

8

Which valve regulates flow from right atrium to right ventricle?

Tricuspid valve

9

Which valve regulates flow out of the right ventricle?

Pulmonary valve

10

Which valve regulates flow out of the left ventricle?

Aortic valve

11

How do the cusps of the mitral and tricuspid valves attach to papillary muscle?

Via chordae tendineae, which prevent inversion of valves on systole.

12

Describe the sequence of electrical conduction in the heart.

- pacemaker cells in SINOATRIAL NODE generate an action potential
- activity spreads over ATRIA
- reaches the AV NODE where it is delayed for 120 ms
- spreads down SEPTUM between ventricles
- spreads through VENTRICULAR MYOCARDIUM from inner to outer epicardial surface
- ventricle contracts from BASE up

13

What are the seven stages of the cardiac cycle?

1) atrial contraction
2) isovolumetric contraction
3) rapid ejection
4) reduced ejection
5) isovolumetric relaxation
6) rapid filling
7) reduced filling

14

When the heart rate increases, what happens to the length of systole and diastole?

Systole remains the same, diastole shortens

15

What does a Wiggers diagram show?

It illustrates the co-ordination of the cardiac cycle, using:
- aortic pressure
- left ventricular pressure
- left atrial pressure
- left ventricular volume
- ECG
- phonocardiogram (heart sounds)

16

What is the relationship between left ventricle volume and left ventricle pressure?

As pressure increases, volume decreases. Aortic pressure also increases simultaneously.

17

What happens in phase 1 of heart contraction?

ATRIAL CONTRACTION

Atrial pressure rises due to atrial systole - this is called the 'A wave'. Ventricular volume peaks.

18

What happens in phase 2 of heart contraction?

ISOVOLUMETRIC CONTRACTION

- mitral valve closes, but aortic valve still closed so volume does not change
- first heart sound (S1) caused by closing of valves
- QRS complex in ECG and C wave in atrial pressure curve

19

What happens in phase 3 of heart contraction?

RAPID EJECTION

- ventricular pressure higher than in aorta so aortic valve opens
- ventricles contract
- atrial pressure initially decreases as atrial base is pulled downwards as ventricle contracts ('X descent')

20

What happens in phase 4 of heart contraction?

REDUCED EJECTION
- repolarisation of ventricle causes rate of contraction to fall
- atrial pressure rises ('V wave')
- T-wave of ECG

21

What happens in phase 5 of heart contraction?

ISOVOLUMETRIC RELAXATION

- brief backflow of blood into ventricle is stopped by aortic valve (dicrotic notch)
- rapid decline in ventricular pressure but volume remains constant as all valves are closed (these cause second heart sound - S2)

22

What happens in phase 6 of heart contraction?

RAPID FILLING

- fall in atrial pressure after mitral valve opens (Y-descent)
- third heart sound (S3) present in children and occasionally (abnormally) in adults

23

What happens in phase 7 of heart contraction?

REDUCED FILLING

- rate of filling slows as ventricle reaches inherent relaxed volume

24

What is aortic valve stenosis?

- valve doesn't open enough, so less blood can get through
- can lead to increased LV pressure -> LV hypertrophy
- can lead to left sided heart failure -> syncope, angina
- shear stress can damage erythrocytes

25

Give some causes of aortic valve stenosis.

- degenerative (senile calcification/fibrosis)
- congenital
- chronic rheumatic fever

26

Give some causes of aortic valve regurgitation

- aortic root dilation
- valvular damage

27

What is it called when a valve doesn't close all the way?

Regurgitation

28

What is it called when a valve doesn't open enough?

Stenosis

29

What are the effects of aortic valve regurgitation?

- blood flows back into LV during diastole, which increases stroke volume
- systolic pressure increases, diastolic pressure decreases

30

Give some symptoms of aortic valve regurgitation

- bounding pulse (head bobbing, Quinke's sign)
- LV hypertrophy

31

Give some causes of mitral valve regurgitation

- Myxomatous degeneration can weaken tissue leading to prolapse
- damage to papillary muscle
- left sided heart failure
- rheumatic fever

32

How does mitral valve regurgitation cause LV hypertrophy?

Some blood leaks back into LA, which increases pre-load and can cause LV hypertrophy

33

What is the main cause of mitral valve stenosis?

Rheumatic fever

34

What does increased LA pressure due to mitral valve stenosis cause?

- pulmonary oedema, dyspnea and pulmonary hypertension which can lead to RV hypertrophy
- LA dilation, which can lead to:
- atrial fibrillation -> thrombus formation
- oesophagus compression -> dysphagia

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