The Cardiac Cycle

Question 1

What are the stages of the cardiac cycle

Answer 1

Stage 1 – Atrial Diastole

Stage 2 - Ventricular Diastole

Stage 3 – Atrial Systole

Stage 4 – Ventricular Systole

Question 2

What does systole mean?

Answer 2

contraction of the heart muscle / when the heart pumps the blood.

Question 3

What does diastole mean?

Answer 3

relaxation of the heart muscle / when the heart fills with blood.

Question 4

What happens in atrial diastole stage?

Answer 4

Atria fill with blood

Atrioventricular valves closed.
Semi-lunar valves open

Question 5

What happens in Ventricular diastole stage?

Answer 5

Rising pressure in atria causes the AV valves to open and ventricles to fill

AV valves open.
Semi-lunar valves closed

Question 6

What happens in atrial systole stage?

Answer 6

Atria contract, forcing blood into ventricles

AV valves open
Semi-lunar valves closed

Question 7

What happens in Ventricular systole stage?

Answer 7

Ventricles contract, increasing pressure in the ventricles and forcing blood into the aorta and pulmonary artery

AV valves are forced to close

Question 8

What are the phases?

Answer 8

Filling phase
Isovolumetric contraction
Outflow phase
Isovolumetric relaxation

Question 9

What happens in the filling phase?

Answer 9

the ventricles fill during diastole and atrial systole

Question 10

What happens in the Isovolumetric contraction phase

Answer 10

the ventricles contract, building up pressure ready to pump blood into the aorta.

Question 11

What happens in the Outflow phase?

Answer 11

the ventricles continue to contract, pushing blood into the aorta and the pulmonary trunk. Also known as systole

Question 12

What happens in the Isovolumetric relaxation phase

Answer 12

the ventricles relax, ready to re-fill with blood in the next filling phase.

Question 13

How do you work out the cardiac output?

Answer 13

Cardiac output = heart rate x stroke volume

Question 14

What is stroke volume?

Answer 14

The amount of blood pumped by the left ventricle of the heart in one contraction
The normal range is 50 to 100 ml.

Question 15

What is the heart`s pacemaker and how does it work?

Answer 15

The sinus node is an area of specialized cells in the upper right chamber of the heart
It sends an electrical impulse to make your heartbeat. The job of a pacemaker is to artificially take over the role of your sinus node if it isn’t working properly.

Question 16

What is an ECG

Answer 16

An ECG is a simple test that can be used to check your heart’s rhythm and electrical activity.
Electrodes are placed on your chest to record your heart’s electrical signals.

Question 17

What does wave P show?

Answer 17

Atrial systole

Excitation of atria so they contract

Question 18

What does wave QRS show?

Answer 18

Ventricular systole

Excitation of ventricles so they contract

Question 19

What does wave T show?

Answer 19

Diastole

When the heart chambers are relaxing.

Question 20

What are the atria

Answer 20

2 top chambers of the heart

Question 21

What is the ventricle?

Answer 21

2 bottom chambers of the heart

Question 22

What is the Sinoatrial node (SAN)?

Answer 22

A patch of tissue in the right atrium that generates the electrical activity and initiates a wave of excitation at regular intervals.

Question 23

What is the Atrioventricular node (AVN)

Answer 23

A patch of tissue found at the top of the septum that picks up the wave of excitation from the atria.

Question 24

What is the Septum?

Answer 24

The dividing wall between the right and left sides of the heart – prevents mixing of blood.

Question 25

What is the Bundle of His

Answer 25

A collection of heart muscle cells specialised for electrical conduction.

Question 26

What are the Purkinje fibres

Answer 26

Specialised conducting fibres found in the heart.