Blood is a vital component of the human body, and it is made up of several different components. Hematin is a complex molecule composed of four parts: IRON, heme, globin, and porphyrin. SERUM is the liquid portion of blood that contains proteins, hormones, and other substances. Heme is a small, IRON-containing molecule that binds to oxygen and carries it throughout the body. IRON is an essential mineral found in red blood cells that helps transport oxygen. PLASMA is the liquid portion of the blood that contains proteins, hormones, and other substances. Plasm is a type of PLASMA that contains antibodies and other proteins. Platelets are small, disc-shaped cells that help form clots to stop bleeding.