composition of the blood

Blood is made up of an aqueous liquid (plasma) in which solids (blood cells, platelets) are suspended. It accounts for 7% to 8% of the body’s weight.

platelet

Blood cell that causes the blood to coagulate, preventing hemorrhaging.

blood vessel

Membranous canal through which blood circulates in the organism; blood vessels form a network about 90,000 mi long.

plasma

Liquid part of blood consisting especially of water, mineral salts and proteins; it allows elements such as nutrients and waste to circulate in the blood.

white blood cell

Blood cell that plays an essential role in the body’s defenses (destruction of infectious agents, production of antibodies).

red blood cell

Blood cell that transports oxygen and contains a pigment (hemoglobin); red blood cells are the most numerous.