3.1.2 Animal transport – Cardiac Cycle Flashcards
(16 cards)
What are the 3 stages of the cardiac cycle?
Atrial systole
Ventricular systole
Diastole
What does systole mean?
To contract
What does diastole mean?
To relax
Which chambers are contracting and relaxing during atrial systole?
Atria – contracting
Ventricles – relaxing
Which chambers are contracting and relaxing during ventricular systole?
Atria – relaxing
Ventricles – contracting
Which chambers are contracting and relaxing during diastole?
Atria – relaxing
Ventricles - relaxing
What happens to the blood in the heart during atrial systole?
Blood is being forced from both atria into the ventricles.
What happens to the blood in the heart during ventricular systole?
Blood is being forced out of the ventricles through the pulmonary artery (to the lungs) and the aorta (to the rest of the body).
What happens to the blood in the heart during diastole?
The blood is entering the atria through the vena cava and pulmonary vein. The atria fill with blood, which starts to ‘trickle’ down into the ventricles.
Which valves are open during atrial systole?
The tricuspid and bicuspid valves are forced open during atrial systole.
Which valves are open during ventricular systole?
The aortic and pulmonary semilunar valves are forced open during ventricular systole (the tricuspid and bicuspid valves are forced shut).
What happens to the valves during diastole?
The aortic and pulmonary semilunar valves are shut.
The tricuspid and bicuspid valves are open as the blood ‘trickles’ down from the atria to the ventricles.
How do pressure differences in the heart cause the tricuspid and bicuspid valves to open?
When the pressure in the atria is greater than the pressure in the ventricles, the valves are forced open.
How do pressure differences in the heart cause the tricuspid and bicuspid valves to close?
When the pressure in the ventricles in greater than the pressure in the atria the valves are pushed shut.
The tendinous cords stop the valves inverting.
How do pressure differences in the heart cause the semilunar valves to open?
When the pressure in the ventricles is greater than the pressure in the pulmonary artery/aorta, the valves are forced open.
How do pressure differences in the heart cause the tricuspid and bicuspid valves to close?
When the pressure in the pulmonary artery/aorta is greater than the pressure in the ventricles, the valves are forced closed.
