the cardiac cycle

Question 1

phases of the cardiac cycle

Answer 1

• diastole (both)
• atrial systole
• ventricular systole

Question 2

what 3 phases are the ventricles filled in

Answer 2

diastole
atrial systole
ventricular diastole

Question 3

what is systole

Answer 3

contraction

Question 4

what is diastole

Answer 4

relaxation

Question 5

what causes the movement of blood from one region to another

Answer 5

pressure difference
high pressure area to a low pressure area

Question 6

what prevents the backflow of blood around the heart
and give their name

Answer 6

AV valves
semilunar valves

Question 7

what are cardiac cells and what does this mean

Answer 7

myogenic
these generate their own contraction and dont require a neural input to initiate a contraction

Question 8

what is the cardiac cycle controlled by

Answer 8

electrical impulses

Question 9

first stage of cardiac cycle

what happens during diastole

Answer 9

• both atria and ventricles are relaxed and under low pressure
• blood flows in through the atria to the ventricles from the pulmonary veins and vena cava
• blood flows into ventricles
• ventricles fill until theyre the same pressure as the veins
• at the end of diastole, atrial systole occurs

Question 10

what happens during atrial systole

Answer 10

• the atrial muscle contracts and pushes a tiny bit more blood into the ventricles (started by the SA node)
• this causes the pressure in the ventricles to become greater than the atria
• the difference in pressure causes the blood to attempt to flow back into the atria
• this closes the AV valves

Question 11

what happens in ventricular systole

Answer 11

at the beginning- both valves are closed
- the ventricle muscles contract
- the pressure difference in the ventricles compared to the pulmonary artery and aorta is steep
- the contraction causes blood to surge through the ventricle opening the semilunar valves and travel into the great arteries

at the end- contraction relaxes and ventricles relax

Question 12

what happens in late ventricular systole early secondary diastole

Answer 12

now that the ventricles have relaxes their pressure decreases
- the pressure in the arteies is greater
- the blood attempts to travel back into ventricles
- this only closes the semilunar valves
- blood is then pumped through the arteries

Question 13

what causes the av valves to open again

Answer 13

when the pressure in the ventricles decrease after systole

Question 14

what is the atrial systole initiated by

Answer 14

a wave of excitation
from the SA node

Question 15

where is the SA node located

Answer 15

in specialised cardiac tissue in the right atrium

Question 16

where does the SA node send electrical impluses
and what does this cause

Answer 16

• to the whole atrial area
• causing a coordinated contraction of both atria at the same time

Question 17

what is the benefit of the electric impulse only traveling to the atrial area

Answer 17

• causes a small time delay between atrial systole and ventricular systole
• makes sure the ventricles are fully filled before they contract

Question 18

what causes ventricular contraction

Answer 18

an electric impulse generated from the atrioventricular node after the SA node impulse has caused a contraction

Question 19

how does the ventricles contract (process)

Answer 19

• AVN picks up the SAN impulse and generates its own
• the impulse is sent through specialised fibres within the septum called as plural bundle of His
• the impulse travels through each purkunje fibre around the whole ventricle
• once the impulse reaches the apex of the heart, the ventricular cardiac muscle contracts from the bottom upwards

Question 20

what is the benefit of the ventricle contracting from the bottom upwards

Answer 20

this navigates the flow of the blood to the aorta or pulmonary artery