ABSTRACT
William Harvey described the circulation of the blood in 1654. Before this, blood vessels had been described and careful anatomical diagrams constructed. Blood was thought to ebb and flow, providing basic nutrition to the body. Harvey recognised the importance of the heart as a pump, the arteries taking blood to the tissues and the veins returning blood from the tissues to the heart. Malpighi described capillaries which connect arteries and veins. They are responsible for the exchange of oxygen and nutrition. Two separate circulations exist, the circulation through the lungs, the pulmonary circulation, and the circulation through the body, the peripheral circulation. The heart consists of four chambers, two on the right and two on the left. The smaller chamber, the atrium, primes the major chamber, the ventricle, which then contracts to eject blood. Blood from the right side of the heart passes through the lungs where it receives oxygen, at the same time removing carbon dioxide. The blood returns from the lungs to the left side of the heart where it is pumped around the body. Arteries from the left side of the heart supply the brain, the chest, the abdomen and the limbs. Blood is collected via small veins which drain into larger veins, returning blood to the right side of the heart.
