Cardiac cycle

Question 1

What is the cardiac cycle?

Answer 1

All events associated with the flow of blood through the heart during one heart beat

Question 2

What are the 3 phases of the cardiac cycle?

Answer 2

Diastole
Isovolumic contraction
Systole

Question 3

What are the 4 stages of diastole?

Answer 3

isovolumic relaxation - valves controlled by pressure gradient. when muscles relax, pressure falls but not change in volume and blood flows through into the atria. 
rapid inflow
slow inflow (diastasic) - when most of blood has travelled through and pressure starts to equalise 
atrial systole - generates more blood flow into ventricle by pressure gradient (20% of stroke volume)

Question 4

What is isovolumic contraction?

Answer 4

Muscle is contracting so pressure is increasing, but the valves haven’t opened yet so there is no volume change
(pressure must exceed threshold)

Question 5

What occurs in systole?

Answer 5

ventricular contraction to eject blood

Question 6

Which valves have choral tendineae?

Answer 6

mitral and tricuspid

Question 7

Damage to which muscle will cause valve inversion?

Answer 7

papillary muscle

Question 8

Define stroke volume

What is average resting stroke volume?

Answer 8

volume of blood ejected from left ventricle with each cardiac cycle

70ml

Question 9

Define cardiac output

What is the average?

Answer 9

volume of blood ejected from left ventricle each minute

5L per min

Question 10

How is cardiac output calculated?

Answer 10

CO = HR X SV

Question 11

What is the normal duration of the cardiac cycle?

Answer 11

0.8 seconds

Question 12

What is the normal PR interval?

Answer 12

<200ms