lecture 7 - CVS 3: the cardiac cycle

Question 1

what is the cardiac cycle?

Answer 1

cycle of pressure and volume changes in the heart chambers overtime the heart contracts and relaxes

Question 2

what are the stages in the cardiac cycle?

Answer 2

1) ventricular filling
2) atrial contraction
3) isovolumic ventricular contraction
4) ventricular ejection
5) isovolumic ventricular relaxation
6) back to start

Question 3

when does contraction occur?

Answer 3

systole

Question 4

when does relaxation occur?

Answer 4

diastole

Question 5

what is isovolumic ventricular contraction?

Answer 5

can generate force but theres no change in the volume of the chamber

closed system

Question 6

where do the sounds of the heartbeat come from?

Answer 6

from the closing of the AV and semilunar valves

Question 7

what is end diastolic volume (EDV)?

Answer 7

maximum volume in the ventricles prior to ventricular systole

Question 8

what is end systolic volume (ESV)?

Answer 8

minimum volume in the ventricles prior to ventricle systole

Question 9

how can you work out SV?

Answer 9

EDV - ESV

Question 10

what is ejection fraction?

Answer 10

fraction of blood we eject from the heart

= SV / EDV

Question 11

the heart sounds

Answer 11

2 main sounds can be heart - lubb dupp

first = AV valves closing 
second = SL valves closing

Question 12

what happens if valves don’t close properly?

Answer 12

blood can leak and the heart has to work harder

reduced efficiency of the heart as a pump

Question 13

diseases of valves

Answer 13

stenosis - cannot fully open

incompetence - insufficiency

Question 14

what is systemic atrial blood pressure

Answer 14

measured at the level of the heart - upper arm

systolic/diastolic
maximum/minimum

120/80 mmHg

Question 15

what happens when you put a stethoscope over an artery?

Answer 15

you shouldn’t be able to hear anything

in a normal artery you have laminar flow

Question 16

how do you test systolic and diastolic pressure by auscultation?

Answer 16

1) inflatable cuff placed above large artery
2) stethoscope below large artery
3) increase pressure to close artery to stop blood flow - exceed normal systolic pressure
4) start to lower pressure in cuff
5) when artery starts to open you get the first korotokoff sound from turbulent flow
6) increase in turbulent flow
7) when cuff pressure if less than diastolic pressure you get laminar flow again - no sound

Question 17

how can you determine systolic and diastolic pressure from auscultation?

Answer 17

first sound = peak systolic pressure

when sound disappears = diastolic pressure

Question 18

what is dichroic notch?

Answer 18

represents when the aortic valves close
• you get some back flow of blood causing a rebound in pressure
• pressure goes up slightly and back down

Question 19

what is mean arterial pressure (MAP)?

Answer 19

pressure in the arteries averaged over time

MAP = DP + 1/3(SP-DP)

Question 20

what is pulse pressure?

Answer 20

difference between SP and DP

SP - DP