The Cardiac Cycle

Question 1

What is the cardiac cycle?

Answer 1

The sequence of mechanical events that occurs during a single heart beat

Question 2

In late diastole, all chambers of the heart are

Answer 2

relaxed

Question 3

Atrial pressure remains slightly greater than ventricular pressure until

Answer 3

ventricles are full distended

Question 4

The cardiac cycle begins when what node initiates the heart beat?

Answer 4

Sinoatrial node

Question 5

Ventricle filling is completed by what?

Answer 5

Contraction of the atria

Question 6

Ventricular volume after filling is known as

Answer 6

End-Diastolic Volume (EDV)

Question 7

What is the normal EDV range?

Answer 7

120-140mL

Question 8

What is the equivalent pressure to EDV?

Answer 8

End-Diastolic Pressure (EDP)

Question 9

What value should EDP be less than?

Answer 9

10 mmHg

Question 10

Ventricular contraction causes a sharp rise in

Answer 10

ventricular pressure

Question 11

What sounds are caused by the closure of the AV valves?

Answer 11

First heart sounds

Question 12

Ventricular depolarisation is associated with what part of the ECG?

Answer 12

QRS complex

Question 13

Is flow into the arteries initially rapid or slow?

Answer 13

Very rapid

Question 14

Rapid ejection can sometimes be heard as a

Answer 14

murmur

Question 15

What effect is there on the aortic pressure when the flow out of the ventricle reverses causing closure of the outflow valve?

Answer 15

There is a small increase in aortic pressure

Question 16

What causes the dicrotic notch?

Answer 16

Sudden drop in pressure after systolic contraction

Question 17

What is the stroke volume?

Answer 17

The amount of blood ejected by the ventricle in one beat

Question 18

During the last two thirds of systole, atrial pressure rises as a result of

Answer 18

filling from the veins

Question 19

The refilling of the ventricles is assisted by what feature of the ventricles?

Answer 19

The elastic recoil of the ventricular walls

Question 20

At rest, what is the difference in length of diastole and systole?

Answer 20

At rest, diastole is twice the length of systole

Question 21

The pressure-volume loop is affected by what two factors of the ventricle?

Answer 21

• contractility
• compliance
• factors that alter refilling/ejection

Question 22

The area of the pressure-volume loop is an indicator of what?

Answer 22

Cardiac function

Question 23

What is the systolic pressure?

Answer 23

Pressure put on the arteries by the pumping of blood throughout the body

Question 24

What is diastolic pressure?

Answer 24

The minimum arterial pressure during relaxation and dilatation of the ventricles of the heart when the ventricles fill with blood

Question 25

What is the mean arterial pressure?

Answer 25

Average arterial pressure during a single cardiac cycle

Question 26

What is end systolic volume?

Answer 26

The volume of blood in a ventricle at the end of systole (contraction) and the beginning of diastole (filling)

Question 27

What is the ejection fraction?

Answer 27

The proportion of EDV that is ejected

Question 28

What is the c-wave?

Answer 28

The small atrial pressure wave resulting from AV valves bulging into the atria

Question 29

What is the v-wave?

Answer 29

When the atrial pressure rises in the last two thirds of systole as a result of filling from the veins

Question 30

What is the isometric contraction period?

Answer 30

The time between the closure of the atrioventricular valves and the opening of the semilunar valves

Question 31

What is the isometric relaxation period?

Answer 31

The early ventricular diastole beginning with a closure of the aortic and pulmonic valves, preceding opening of atrioventricular valves

Question 32

As contraction reduces in ejection, ejection is reduced, what is this known as?

Answer 32

The reduced ejection phase

Question 33

In ejection, the initial flow into the arteries is very rapid, what is this known as?

Answer 33

Rapid ejection phase

Question 34

What is a phonocardiogram?

Answer 34

The recording of the sounds made by the heart in a cardiac cycle using a phonocardiograph

Question 35

In late diastole, do ventricles fill actively or passively?

Answer 35

Passively

Question 36

In atrial systole, atrial contraction forces what?

Answer 36

A small amount of additional blood into the ventricles

Question 37

What effect does isovolumic ventricular contraction have on the AV valves?

Answer 37

Pushes AV valves closed

Question 38

What happens as ventricular pressure rises and exceeds pressure in the arteries in ventricular ejection?

Answer 38

The semilunar valves open and blood is ejected

Question 39

In isovolumic ventricular relaxation, as ventricles relax and pressure in ventricles falls, what happens to blood flow?

Answer 39

Blood flows back into the cusps of semilunar valves and snaps them closed