Double Circulation and Portal System (Leaving Cert Biology): Revision Notes

Double Circulation

• The heart is a double pump.
• It pumps blood through the body in a double circulation system:
  1. Pulmonary circuit (to and from the lungs)
  2. Systemic circuit (to and from the rest of the body).

1. Pulmonary Circuit

• Pumps blood to the lungs for oxygenation.
• Blood exits the pulmonary artery and returns oxygen-rich via the pulmonary vein.

2. Systemic Circuit

• Pumps oxygenated blood around the rest of the body.
• Blood exits the aorta and returns deoxygenated via the vena cava.

Advantages of Double Circulation

1. Oxygen rich and oxygen poor blood are kept separate.
2. High-pressure pumping: Allows blood to reach all parts of the body quickly, delivering oxygen and nutrients quickly to tissues and organs, supporting their proper function and health.

Portal System

• The Hepatic Portal Vein connects the stomach and intestines with the liver.
• It transports glucose and amino acids.