Week 1 - The Cardiac Cycle

Question 1

What is systole and diastole?

Answer 1

systole is the ejection of blood from the heart. semilunar valves open. diastole is the filling phase.

Question 2

How much of the cardiac cycle occurs during systole and diastole?

Answer 2

2/3rds is diastole. 1/3rd is systole

Question 3

What are the 5 stages of the cardiac cycle?

Answer 3

Diastole, atrial systole, isovolumic ventricular contraction, ventricular ejection, isovolumic ventricular relaxation

Question 4

What occurs during atrial systole?

Answer 4

SA node spreads depolarisation around the atrium and contracts, squeezing the last bit of blood out

Question 5

what occurs during isovolumic ventricular contraction?

Answer 5

ventricles depolarise to close the mitral and tricuspid valves shut so blood doesnt go back into atria. isovolumic as ventricles are contrcating to build up pressure, but theres nowhere for blood to go.

Question 6

What occurs in ventricular ejection?

Answer 6

pressure in ventricles exceed aorta and pulmonary trunk, so aortic and pulmonary valves open and blood is pushed through

Question 7

What occurs in isovolumic ventricular relaxation?

Answer 7

after ejection, pressure falls in ventricles and semilunar valves shut. blood then fills into aorta slowly until pressure exceeds ventricles and pushes valves open again.

Question 8

What occurs in late diastole phase?

Answer 8

tricuspid and mitral valves open and blood passively fills ventricles

Question 9

What is the systolic and diastolic pressure?

Answer 9

systolic - maximum pressure in aorta. diastolic - minimum pressure in aorta

Question 10

What is pulse pressure?

Answer 10

difference between systolic and diastolic pressures

Question 11

When do we see systolic pressure and what’s its pattern?

Answer 11

when ventricle depolarises, graph shoots up from 80 to 120mmHg. as semilunar valves shut, pressure decreases slowly, but theres a notch where elastic recoils as aorta is elastic.

Question 12

When does diastolic pressure end?

Answer 12

when pressure in aorta gets low, about 80mmHg, and this is lower than the pressure in the ventricles.

Question 13

What is the pattern of volume and pressure in the left atrium?

Answer 13

3 waves - a, c and v.
- a wave is atrial contraction in atrial systole
- c wave is mitral valve closing and bulging into left atrium
- v wave is slow increase in pressure as blood is continuously flowing int atrium from L&R vena cavas. drops rapidly as mitral valve opens.

Question 14

What is EDV and ESV? Values?

Answer 14

end diastolic volume and end systolic volume. 140ml and 60ml

Question 15

What is the stroke volume?

Answer 15

difference between EDV and ESV - amount of blood that’s ‘stroked’ in ventricular contraction

Question 16

Why is stroke volume not useful and what do we use instead?

Answer 16

it varies from person to person. bigger people have a bigger stroke volume. we use ejection fraction - percentage of blood in the ventricle thats pumped out. 60% is normal.

Question 17

What is the isometric contraction phase?

Answer 17

semilunar valves shut and ventricle is contracting but volume is constant.

Question 18

What is the rapid ejection phase?

Answer 18

semilunar valves open due to pressure and blood is shot out quick and short movement with high pressure. volume decreases quickly.

Question 19

What is the slower ejection phase?

Answer 19

towards end of ventricular systole, blood pumped slighlty slower out (still FAST)

Question 20

what is isometric relaxation phase?

Answer 20

ventricle isn’t contracting and all valves are shut. atrium is filling. ventricle stays at 60ml

Question 21

What is the rapid filling phase?

Answer 21

diastole. atrium has higher pressure than ventricles and valves open - blood quickly fills ventricles

Question 22

How many heart sounds do we have and which are hearable?

Answer 22

4. only 1 and 2 are hearable and they are closure of mitral and tricuspid valves, and closure of semilunar valves

Question 23

What are the 3rd and 4th heart sounds?

Answer 23

3rd is rapid passive filling phase.
4th is active filling phase - atria contracts.

Question 24

What do we use to record the sounds made by the heart?

Answer 24

phonocardiogram

Question 25

What may cause a heart murmur?

Answer 25

• may be normal.
• continuous murmur may be patent ductus arteriosus
• systolic murmur could be stenosis of aortic/pulmonary valves, or regurgitation through mitral/tricuspid valves
• diastolic murmurs could be stenosis of mitral/tricuspid valves, or regurgitation back through aortic/pulmonary valves