The cardiac cycle

Question 1

What is the first stage in the cardiac cycle

Answer 1

Late diastole - both sets of chambers are relaxed and ventricles fill passively

Question 2

What is the second stage in the cardiac cycle

Answer 2

atrial systole - atrial contraction forces a small amount of blood into the ventricles

Question 3

What is the third stage in the cardiac cycle

Answer 3

Isovolumic ventricular contraction - first phase of ventricular contraction is enough to close the AV valves but not enough to open the semi lunar valves

Question 4

What is the fourth stage in the cardiac cycle

Answer 4

Ventricular ejection - as the ventricles pressure exceeds the atrial pressure, its causes the semi lunar valves to open and blood be expelled from the ventricles

Question 5

What is the fifth stage in the cardiac cycle

Answer 5

Isovolumic ventricular relaxation - Ventricles relax, causing a decreases in pressure, blood flows back on to the semi lunar valves and snaps them closed

Question 6

What is responsible for the a wave in measuring atrial pressure in the heart

Answer 6

A wave follows the p wave on an ECG

Therefore shows arterial depolarisation causing an increase in arterial pressure

Question 7

What valves open and shut to create the c wave in arterial pressure in the heart

Answer 7

c wave starts as soon as mitrovalve closes and stops as soon as aortic valve opens

Question 8

What is responsible for the V wave in the measure of arterial pressure in the lungs

Answer 8

due to venous return coming back to the lungs in systolic stage through pulmonary vein

Question 9

What causes the arterial pressure to decrease and match the ventricle pressure in the lungs

Answer 9

Mitral valve opens

Question 10

What causes the massive increase in ventricle pressure in the heart

Answer 10

Mitral valve close causing the pressure in the ventricles to increase as are filled with blood

Question 11

What triggers the aortic valves to open

Answer 11

When ventricular pressure exceeds aortic pressure

Question 12

What causes the aortic valve to close

Answer 12

When ventricular pressure decreases as muscles relax from pushing out stoke volume, blood flows back on to the aortic valves and snaps them closed

Question 13

What causes the dicrotic notch in the aortic pressure

Answer 13

ventricles push out the blood, it absorbs energry, releases blood then the aortic valve shuts causing a rebound in pressure

Question 14

What causes further decrease in aortic pressure, and equalises ventricular and arterial pressure

Answer 14

Mitral valve opening

Question 15

What is the usually end diastolic pressure (EDV)

Answer 15

140ml

Question 16

What is the usually end systolic volume

Answer 16

60ml

Question 17

What is it important for there to be end systolic volume

Answer 17

So heart doesn’t pump all the blood thats in it - reserve for exercise

Question 18

How is the stroke volume determined

Answer 18

The difference between EDV and ESV

Question 19

How do you calculate the ejection fraction

Answer 19

SV/EDV

Question 20

What is the clinical importance of the ejection fraction

Answer 20

As stroke volume will vary according to the person, where ejection fractions shows how much of the blood present in the heart is pumped out

Question 21

What should the ejection fraction typically be

Answer 21

2/3rds

Question 22

Why does doubling the heart rate have little effect on diastolic volume

Answer 22

As increasing heart rat has little effect on filling stage but rather how fast blood can be expelled from the heart

Question 23

What is the difference between right and left side of the heart in terms of pressure and volume and why

Answer 23

Volume of the right and left side is the same, however the pressure of the right side is much less due to less force needed to push blood around pulmonary circulation rather than systemic circulation

Question 24

What is the effect of mitral valves opening on the pressure and the volume of the left ventricles

Answer 24

The left ventricles volume increases while pressure remains the same

Question 25

What happens to cause mitral valves to close

Answer 25

Ventricular pressure increases

Question 26

What is called when the ventricular pressure is increases with a high volume of blood in the lungs that cant escape

Answer 26

isometric contraction stage

Question 27

What valve opens to allow blood out to the body, and what effect does this have on ventricular pressure and volume

Answer 27

Aortic valve open

This means ventricular pressure continues to increase as stroke volume is pushed out and ventricles volume decreases

Question 28

After the volume of stroke volume is fully expelled from the lungs what happens to the ventricular pressure and volume

Answer 28

The ventricular pressure decreases again, while the End systolic volume remains constant

Question 29

What does the decrease in ventricular pressure have on the effect of the aortic valve

Answer 29

Causes the aortic valve to shut

Question 30

What is the typical lub dub sound caused by a phonocardiogram
How is this sound created

Answer 30

Mitral & tricuspid valves closing
followed by
Aortic & pulmonary valves closing

The turbulence of the blood caused by the valves shutting

Question 31

What does a phonocardiogram investigate

Answer 31

Heart murmurs - abnormal heart rhythms

Question 32

What features of the valves can cause heart murmurs

Answer 32

Stenosis of valves

Regurgitation of valves

Question 33

What continues to pick up a continual rhythm on the phonocardiogram

Answer 33

septum defect

Question 34

When is the rapid filling stage

Answer 34

start of diastole when the mitral valve open

Question 35

What causes the rapid ejection stage

Answer 35

systolic pressure exceeding aortic pressure - aortic valves open

Question 36

What causes the isometric contraction stage

Answer 36

When the pressure increases but the blood remains in the ventricles