Your blood is living tissue made up of liquid and solids. The liquid part, called plasma, is made of water, salts and protein. Over half of your blood is plasma. The solid part of your blood contains red blood cells, white blood cells and platelets.

Red blood cells deliver oxygen from your lungs to your tissues and organs. White blood cells fight infection and are part of your body's defense system. Platelets help blood to clot. Bone marrow, the spongy material inside your bones, makes new blood cells. Blood cells constantly die and your body makes new ones. Red blood cells live about 120 days, platelets 6 days and white cells less than a day.

There are many types of blood disorders, including: bleeding disorders, hemophilia and anemia. If you lose blood, you may need a transfusion.

What is Blood

Blood carries gases, nutrients and waste products through the body. Blood also fights infections, heals wounds and performs many other vital functions. There is no substitute for blood. It cannot be made or manufactured. Donors are the only source of blood for patients who need it.

One unit of blood can be separated into components: red blood cells, white blood cells, plasma, platelets and cryoprecipitate.