The Composition of Blood

The bulk of blood volume is pale yellow plasma. Another 30 to 45 percent is red blood cells, and the remainder is white cells and platelets. In kittens, the liver and spleen make blood cells; in adults bone marrow produces them.

Plasma in the blood provides transportation, carrying nutrients from the digestive system, and transporting waste. Levels of plasma are maintained by liquid absorbed  along the length of the large intestine.

Red cells carry oxygen through the arteries to the cell of the body. Oxygen attaches to a red-pigmented protein called hemoglobin in create the cells to create oxyhemoglobin, which is bright red in color.

The oxygen diffuses through capillary walls into cell tissue. In return, carbon dio[ide diffuses into the veins and attaches to hemoglobin to make blue-red methemoglobin.

White blood cells defend the body against microbes and parasites, clear waste from injuries, detoxify substances released in allergic reactions, and help the body to acquire immunity against infections by producing antibodies. Disk-shaped platelets help to clot blood around wounds.