Circulatory System

• The heart is at the centre of the circulatory system
• Mammals have a double circulatory system. This means the blood will flow through the heart twice in one circuit: -deoxygenated blood is pumped to the lungs. -oxygenated blood is pumped around the body.
• The heart is a muscle that is constantly contracting and relaxing. This means that the heart muscles need a constant supply of oxygen for respiration. The coronary arteries supply blood to the heart.
• Deoxygenated blood is pumped out of the heart to the lungs via the pulmonary artery. Oxygen diffuses into the deoxygenated blood into the lungs and the blood becomes oxygenated.
• Blood in the aorta is at a very high pressure to ensure the blood can be pumped to all tissues in the body.
• Oxygen dissociated from the blood at respiring cells in the body and the blood become deoxygenated.