Cardiac cycle

Question 1

How do we calculate arterial blood pressure?

Answer 1

ABP = SV x HR x TPR

Question 2

What may change the cardiac cycle?

Answer 2

Exercise

Heart failure

Question 3

What can be used to measure pressure changes?

Answer 3

Cardiac catheter

Echocardiography

Question 4

What is the chain of events in the cardiac cycle?

Answer 4

Electrical activity
Mechanical activity
Pressure changes
Volume changes

Question 5

Whats the average duration of the cardiac cycle?

Answer 5

850ms

Question 6

What is the average duration of diastole?

Answer 6

600ms

Question 7

What is the average duration of systole?

Answer 7

200ms

Question 8

What increases pressure in a chamber?

Answer 8

The muscle around it contracting

Question 9

What variables affect pressure changes?

Answer 9

Thickness of the muscle

Question 10

What opens valves?

Answer 10

A positive pressure gradient

Question 11

Where does blood move?

Answer 11

Down a pressure gradient

From high pressure to low pressure

Question 12

What is the first stage of the cardiac cycle?

Answer 12

Ventricular pressure falls below atrial pressure
Mitral valve opens
Atrial blood flows into ventricle
“Rapid filling”
Aortic valve remains closed as aortic pressure is greater than ventricular pressure

Question 13

What happens at the end of ventricular diastole?

Answer 13

Atrial systole

Question 14

What is the result of atrial systole?

Answer 14

A little more blood added to the ventricles

5ml of 120-130ml

Question 15

What is the second stage of the cardiac cycle?

Answer 15

Ventricular systole
Ventricular pressure higher than atrial pressure
Mitral valve closes
Aortic valve still closed
"Isovolumetric contraction"

Question 16

What is meant by isovolumetric contraction?

Answer 16

Contracting the same volume of liquid
No change of volume
All valves closed

Question 17

What is the third phase of the cardiac cycle?

Answer 17

Ventricular ejection
Ventricular pressure higher than aortic pressure
Aortic valve opens

Question 18

How come the aortic valve doesn’t shut soon after open?

Answer 18

Regardless of the pressure gradient, momentum keeps the aortic valve open

Question 19

What is the fourth phase of the cardiac cycle?

Answer 19

Ventricular diastole
Aortic valve closes
Mitral valve still closed
This is called isovolumetric relaxation

Question 20

What is the end systolic volume and what is its role?

Answer 20

50ml of blood

In case of need to rapidly increase stroke volume

Question 21

What are normal pressures in the aorta?

Answer 21

120/80

Question 22

What are normal pressures in the pulmonary artery?

Answer 22

25/10

Question 23

What are normal pressures in the right atrium?

Answer 23

4

Question 24

What are normal pressures in the right ventricle?

Answer 24

25/4

Question 25

What are normal pressures in the left atrium?

Answer 25

8

Question 26

What are normal pressures in the left ventricle?

Answer 26

120/8

Question 27

What is the equation for flow?

Answer 27

Pressure/resistance

Question 28

What is flow equivalent to in the cardiovascular system?

Answer 28

Cardiac output

Question 29

Right cardiac output and left cardiac output are what?

Answer 29

Equal

Question 30

Explain the differences in ventricular wall thickness

Answer 30

TPR is lower in pulmonary system than vascular. Left ventricle has to create higher pressures