Blood is the life-maintaining fluid that circulates through the body's heart, arteries, veins, and capillaries. It carries away waste matter and carbon dioxide, and brings nourishment, electrolytes, hormones, vitamins, antibodies, heat, and oxygen to the tissues.
Because the functions of blood are many and complex, many disorders require clinical care by a physician or other health care professional. These conditions include benign (noncancerous) disorders, as well as cancers that occur in blood.