Cardiac cycle and coordination

Question 1

What occurs in diastole?

Answer 1

Atria and ventricles are both relaxed.
Aorta and pulmonary artery pressure is higher than that in the ventricles.
Semilunar valves are shut preventing back flow of blood into the ventricles
Allows time for blood to enter atria again

Question 2

Contraction increases the …

Answer 2

Pressure

Question 3

What is atrial systole
.Pressure
.Direction of blood
.valves

Answer 3

Pressure in atria is higher than ventricular pressure as blood has entered atria from vena cava and pulmonary vein

the pressure causes the Atrioventricular valves to open- allowing blood to flow down from atria to ventricles.

Atrial contraction/systole occurs, pushing remaining blood from atria to enter ventricle

Question 4

What is ventricular systole

Answer 4

Atria is now relaxed and av valves are closed to prevent back flow of blood.
Ventricular pressure is now higher than atrial pressure
Semi lunar valves are now open to allow blood to enter the arteries.
Ventricular systole occurs and forces blood into arteries.

Question 5

What is the lub- dub sound

Answer 5

Lub- atrioventricular valves closing
Dub- semi-lunar valves closing

Question 6

In ventricle systole, the ventricle contracts from the apex upwards. How come?

Answer 6

so blood is pushed towards the arteries

Question 7

During atrial systole, there is only a small rise in pressure, how come?

Answer 7

the muscle in the wall is only thin, so only a small increase in pressure is created

Question 8

Why is it suitable for the atria to not generate as much pressure as the ventricles

Answer 8

Because the role of the atria is to receive blood and fill the ventricles, not a lot of pressure is needed

Question 9

What does the green line show

Answer 9

Ventricular pressure

Question 10

what does the red line show

Answer 10

Aortic pressure

Question 11

when looking at the graph displaying pressure change during the cardiac cycle. What three things is it important to describe

Answer 11

-comparisons between pressure
-Different valves
-direction of blood

Question 12

what is the role of tendinous chords

Answer 12

prevent valves turning inside out

Question 13

Cardiac muscles are considered myogenic. what does it mean

Answer 13

Myogenic means the heart controls its own contractions by initiating its own electrical excitation waves.

Question 14

What are the 4 components in the heart used to coordinate the cardiac cycle

Answer 14

Sino atrial node
Atrioventricular node
Bundle of his
Purkyne fibres

Question 15

Where is the Sino-Atrial node located

Answer 15

In the upper wall of the right atria

Question 16

Why is the SAN also known as a natural pace maker

Answer 16

Because it initiates the wave of excitation

Question 17

where does the SAN send the wave of excitation

Answer 17

through the walls of the atria to enable atrial systole, the wave is then sent to the atrioventricular node

Question 18

Why is there a delay of the wave of depolarisation from the SAN to the AVN

Answer 18

The delay allows the atria to fully contract and allows blood to enter the ventricle.

Question 19

Where is the wave of excitation sent from the AVN

Answer 19

the wave is transmitted from the AVN to the bundle of his

Question 20

Where is the bundle of his located

Answer 20

In the septum of the heart

Question 21

How come the transmission of the wave of depolarisation through the bundle of his doesn’t conduct ventricular systole

Answer 21

Because there is a insulating layer around the bundle of his, therefore the wave of excitation can pass without contraction

Question 22

After the bundle of his, the wave of depolarisation is sent to the Purkyne Fibres. Where are these located in the heart?

Answer 22

In the walls of the ventricle

Question 23

The wave of excitation is spread through the Purkyne fibres, from the apex of the heart then upwards. Why?

Answer 23

So the blood is pushed towards the semi-lunar valves