The Cardiac Cycle

Question 1

What does systole mean ?

Answer 1

Contraction / Contracting.

Question 2

What does diastole mean ?

Answer 2

Relax / Relaxing.

Question 3

Explain what happens in the heart during the atrial systole stage ?

Answer 3

The atria contract forcing the atrioventricular valves open. Pushing blood in atria down into the ventricles.

Question 4

delete Explain what happens in the heart during the cardiac diastole stage.

Answer 4

The atria and ventricles are relaxed just as the previous cycle had ended. Blood enters the atria (through the vena cava and pulmonary vein) increasing the pressure in the atria at a certain point the pressure in the atria is greater than the pressure in the ventricles. This pushes open the atrioventricular valves. This allows blood to flow into the ventricles. Pressure in the heart is lower than in the arteries, so the semilunar valves remain closed.

Question 5

Explain what happens during the ventricular systole stage.

Answer 5

• The ventricles contract.
• Causing the atrioventricular valves to close, to prevent the back flow of blood from the ventricles into the atria.
• The the semi lunar valves open. So blood is pumped from the ventricles out of the heart.

Question 6

Answer 6

Question 7

Answer 7

Question 8

Answer 8

Question 9

Answer 9

Question 10

Answer 10

• smooth endothelium lining so that there is less friction to blood flow
• Narrow lumen to maintain blood at high pressures.
• Elastic fibres so that it is able to stretch to accommodate high pressures.