The Heart As A Pump

Question 1

What is systole?

Answer 1

Contraction and ejection of blood from ventricles

Question 2

What is diastole?

Answer 2

Relaxation and filling of ventricles

Question 3

What is stroke volume?

Answer 3

The volume of blood pumped by each beat.
Approx. 70ml per beat

Question 4

How much blood in the average adult?

Answer 4

5 litres

Question 5

What valve is found between the left atrium and ventricle?

Answer 5

Mitral valve

Question 6

Where is the tricuspid valve found?

Answer 6

Between the right atrium and ventricle

Question 7

What is the valve exiting the left ventricle called?

Answer 7

Aortic valve

Question 8

What is the valve exiting the right ventricle called?

Answer 8

Pulmonary valve

Question 9

What prevents the inversion of mitral and tricuspid valves during systole?

Answer 9

Chordae tendinae attach the valves to papillary muscles

Question 10

Describe the conduction system in the heart

Answer 10

Pacemaker calls in the SA node generate action potential. Activity spreads over atria - atrial systole. Reaches the AV node and delayed for about 120ms. From AV node, excitation spreads down septum between ventricles. Next spreads through ventricular myocardium from endocardial to epicardial surface. Ventricle contracts from the apex up forcing blood through outflow valves

Question 11

What is the first heart sound (s1) due to?

Answer 11

Closure of the mitral and tricuspid valves at the start of isovolumetric contraction

Question 12

What is the second heart sound (s2) caused by?

Answer 12

Closure of aortic and pulmonary valves

Question 13

What is valve stenosis?

Answer 13

Valve doesn’t open enough -> obstruction to blood flow when valve normally open

Question 14

What is valve regurgitation/incompetence/insufficiency?

Answer 14

Valve doesnt close all the way -> back leakage when valve should be closed

Question 15

Causes of aortic valve stenosis.

Answer 15

Degenerative - senile calcification/fibrosis
Congenital - bicuspid form of valve
Chronic rheumatic fever - inflammation - commissural fusion
Crescendo-decrescendo murmur

Question 16

Aortic valve regurgitation

Answer 16

Aortic root dilation - leaflets pulled apart.
Vlavular damage - endocarditis rheumatic fever

Early decrescendo diastolic murmur

Blood flows back into LV during diastole -> increase in stroke volume -> LV hypertrophy

Question 17

Mitral valve regurgitation

Answer 17

Myxomatous degeneration can weaken tissue leading to prolapse
Damage to papillary muscle after heart attack
Left sided heart failure leads to LV dilation which can stretch valve
Rheumatic fever can lead to leaflet fibrosis which disrupts seal formation

Holosystolic murmur

Some blood leaks back into LA, increasing preload -> more blood enters LV -> can cause LV hypertrophy

Question 18

Mitral valve stenosis

Answer 18

Due to rheumatic fever in majority of cases
Commissural fusion of valve leaflets

Snap as valve opens. Diastolic rumble

RV hypertrophy due to pulmonary oedema, dyspnea and pulmonary hypertension