Cardiac cycle and blood flow through the heart

Question 1

What happens in stage 1 of the blood ejection process?

Answer 1

Oxygen-depleted blood enters the right atrium from the superior and inferior vena cavae. The right atrium contracts and pushes blood through the tricuspid valve into the right ventricle.

Example: Deoxygenated blood enters the right atrium from the vena cavae.

Question 2

What happens in stage 2 of the blood ejection process?

Answer 2

The right ventricle contracts and pushes blood through the pulmonary valve into the pulmonary trunk and pulmonary arteries and into the lungs. The pulmonary arteries are the only arteries that transport oxygen-depleted blood. Once blood is reoxygenated, the pulmonary veins transport blood from the lungs to the left atrium. The pulmonary veins are the only veins that transport oxygen-rich blood.

Additional Information: Pulmonary veins transport oxygen-rich blood.

Question 3

What happens in stage 3 of the blood ejection process?

Answer 3

Blood moves from the left atrium through the mitral valve and enters the left ventricle. The left ventricle contracts and blood moves through the aortic valve into the aorta and then to body cells.

Example: Blood moves from the left atrium to the left ventricle through the mitral valve.