7.5 The Cardiac Cycle

Question 1

What are the two phases to the beating of the heart

Answer 1

1. Contraction - Systole

2. Relaxtion - Diastole

Question 2

Process of diastole

Answer 2

Blood enters atria and ventricles from pulmonary veins and vena cava

Semi lunar valves are closed

Bicuspid and tricuspid valves open

Relaxation of ventricles allows blood to enter from atria

Question 3

Process of atrial systole

Answer 3

Atria contract to push remaining blood intro ventricles

Semi-lunar valves closed

Bicuspid and tricuspid valves open

Blood is pumped from atria to ventricles

Question 4

Process of ventricular systole

Answer 4

Blood pumped into pulmonary arteries and the aorta

Semi lunar valves open

Tricuspid and bicuspid valves closed

Ventircles contract and walls thicken

Question 5

When are the two ‘dubs’ of the heart

Answer 5

1. The closing of the semi-lunar valves in the aorta and pulmonary arteries during diastole
2. The closing of the atrioventricular valves during ventricular systole

Question 6

What are valves used for

Answer 6

Preventing the backflow of blood

Question 7

When are valves in the cardiovascular system designed to open

Answer 7

Whenever the difference in blood pressure either side of them favours the movement of blood in the required direction

Question 8

What are examples of the valves used in the cardiovascular system

Answer 8

1. Atrioventricular valves
2. Semi-lunar valves
3. Pocket valves

Question 9

Where are the atrioventricular valves (bicuspid and tricuspid)

Answer 9

Between the left atrium and ventricle and right atrium and ventricle

Question 10

What do the atrioventricular valves prevent blood from doing

Answer 10

They prevent the backflow of blood when contraction of the ventricles means that ventricular pressure exceeds atrial pressure

Question 11

Where are semi-lunar valves

Answer 11

In the aorta and pulmonary artery

Question 12

What do the semi-lunar valves prevent blood from doing

Answer 12

They prevent the backflow of blood into the ventricles when the pressure in these vessels exceeds that in the ventricles

Question 13

Where are pocket-valves

Answer 13

Inside veins

Question 14

What do the pocket valves prevent blood from doing

Answer 14

Blood flowing away from the heart rather than towards it

Question 15

What is cardiac output

Answer 15

the volume pof blood pumped by one ventricle of the heart in one minute

Question 16

What two factors does cardiac output depend on

Answer 16

1. Stroke volume

2. Beats per minute

Question 17

How do you calculate cardiac output

Answer 17

Stroke volume X beats per minute

Question 18

What is the units for cardiac output

Answer 18

Dm^3m-1