the cardiac cycle

Question 1

describe the cardiac cycle?

Answer 1

1. late daistole- both sets of chambers are relaxed and ventricles fill passively
2. atrial systole- strial contraction forces a small amount of additional blood into ventricles
3. isovolumic ventricular contractiuon- first phase of ventricular contraction pushes AV vavles closed but does not create enough pressure to open semilunar valves
4. ventricular ejection- as ventricular pressure rises and sxceeds pressure in the arteries, the semilunar valves open and blood is ejected
5. isovolumetric ventricular relaxation- as ventricles relax, pressure in the ventricles falls, blood flows back into the cusps of semilunar valves and they close

Question 2

what is used instead of stoke volume to assess the healthiness of someone’s heart?

Answer 2

the ejection fraction (stoke volume/ end diastolic volume)

Question 3

is stroke volume clinically relevant?

Answer 3

no, as it depends purely on the size of the person

Question 4

what causes the first heart sound?

Answer 4

the closing of the mitral and tricuspid valves

Question 5

what causes the second heart sound?

Answer 5

the closing of the bicuspid valves i.e. aortic and pulmonary valves

Question 6

what is normal systolic pressure at rest?

Answer 6

120 mmHg

Question 7

what is normal diastolic pressure at rest?

Answer 7

80 mmHg

Question 8

what is a rough estimate of mean arterial pressure?

Answer 8

diastolic pressure plus a 3rd of pulse pressure

Question 9

what is considered a normal ejection fraction?

Answer 9

> 55%

Question 10

what can cause a systolic murmur?

Answer 10

stenosis of aortic/pulmonary valves or regurgitation through mitral/tricuspid

Question 11

what causes a diastolic murmur?

Answer 11

stenosis of mitral/ tricuspid valves
or
regurgitation through aortic/pulmonary valves

Question 12

what causes a diastolic and systolic murmur?

Answer 12

septal defect

or calcification of valves causing stenosis and regurgitation