3. Blood vessels that receive blood

3. Blood vessels that receive blood from the ventricle and lead it away from the heart and towards other organs are arteries («air duct» - Greek). The vessels received this name because the early anatomists assumed that they had been empty in dead persons and had carried air.The artery that takes up the blood from the right ventricle and carries it to the lungs is the pulmonary artery («lungs» - Latin). The pulmonary artery divides in two - one branch leads to the right lung, the other - to the left. The arteries continue to divide and subdivide and form smaller and smaller vessels with thinner and thinner walls. The smallest arteries are the arterioles and these finally divide into capillaries («hairlike» - Latin). We name them so because of their fineness, though actually they are much finer than hairs.

4. Gradually the capillaries begin to join into larger vessels. Such larger blood vessels that carry blood to the heart from the organs are the veins. The smallest of these are the venules.

5. The particular vein into which the capillaries and venules of the lungs finally unite is the pulmonary vein. The pulmonary vein carries the freshly oxygenated blood to the left auricle. The pulmonary artery and pulmonary vein make up the pulmonary circulation.

6. The contraction of the left ventricle forces the blood through a one-way valve into the aorta («to lift up» - Greek). The aorta is the largest artery in the body. It moves upward at first (the ascending aorta), but then arches over dorsally (the arch of the aorta). In its downward course, the aorta passes through the diaphragm.

7. The blood is a red fluid, which coagulates when escapes from a blood vessel. It consists of a colourless fluid, plasma or serum, and many millions of minute bodies, the corpuscles.