Blood Flow Through the Heart (Leaving Cert Biology): Revision Notes

Blood Flow Through The Heart

The heart pumps blood through the body in a double circulation system:

1. Pulmonary Circulation (to and from the lungs).
2. Systemic Circulation (to and from the rest of the body).

Blood Flow Through the Heart

1. Deoxygenated blood enters the right atrium of the heart (from all over the body) through the vena cava.
2. The right atrium pumps the blood down to the right ventricle through the tricuspid valve.
3. The right ventricle pumps the blood out through the pulmonary artery to the lungs.
4. Oxygenated blood enters the left atrium of the heart (blood coming from the lungs) through the pulmonary vein.
5. The left atrium pumps the blood through the bicuspid valve to the left ventricle.
6. The left ventricle pumps the blood out to the rest of the body through the aorta.

Additional Notes:

• The tri and bicuspid valves ensure that blood does not flow back into the atria from the ventricles.
• The semi-lunar valves ensure that blood does not flow back into the heart from the pulmonary artery and the aorta.
• The walls of the atria are thin. Blood only has to be pumped a short distance to the ventricles.
• The walls of the ventricles are much thicker as blood is pumped a long distance.