Cardiac cycle

Question 1

3 Stages of cardiac cycle

Answer 1

Diastole
Atrial systole
Ventricular systole

Question 2

What happens during diastole in terms of contraction?

Answer 2

Both the atria and ventricles are relaxed as blood from pulmonary vein/ vena cava fills the atria

Question 3

What happens during diastole in terms of the valves?

Answer 3

Because the pressure in atria is bigger than in ventricles due to the filling of blood into atria which increases pressure slightly
then this causes the atrioventricular valves to open and blood to fill ventricle
Semi lunar valves closed

Question 4

What happens during diastole in terms of ventricular volume?

Answer 4

Slowly increases as blood from atria empties into ventricles

Question 5

What happens during atrial systole in terms of contractions?

Answer 5

The atria contract decreasing volume in atria, increasing pressure
The ventricles will remain relaxed, so pressure in atria>pressure in ventricle

Question 6

What happens in atrial systole in terms of valves?

Answer 6

The atrial ventricular valves are open because pressure in atria is larger than in ventricles

Question 7

What happens in atrial systole in terms of volume of blood in ventricles?

Answer 7

Increased in ventricular volume of blood due to blood being forced from the atria into the ventricles due to contraction of atria

Question 8

Why is there delay in semi lunar valve opening before atria ventricular valve closes?

Answer 8

So blood isn’t flowing in2 directions

Question 9

What happens in ventricular systole in terms of contractions?

Answer 9

The ventricles contract and atria remain relaxed
So volume of ventricle decreases and pressure inside increased

Question 10

What happens in ventricular systole regarding the valves?

Answer 10

The pressure in ventricles increased due to contracting So semi lunar valves will open because pressure in ventricles greater than in artery/pulmonary artery

Question 11

When does the semi lunar valve shut?

Answer 11

When ventricles stop contracting because all blood has been forced into aorta/pulmonary artery
And so the pressure in aorta/pulmonary artery is greater than in the ventricles

Question 12

How do atrioventricular valves prevent back flow of blood?

Answer 12

Close when the pressure in atria no longer is high because atria stopped contracting
Because contraction of ventricle is delayed, this means when it does the blood is not forced into atria again because the av valves are closed

Question 14

Stroke volume

Answer 14

Volume of blood pumped per heart beat

Question 15

Heart rate

Answer 15

Beats per minute

Question 16

Cardiac output

Answer 16

Heart rate (beats per minute) x the stroke volume