Blood is a vital component of the human body, composed of several different elements. PLASMA, which is composed of water, proteins, and other substances, makes up 55% of the blood and serves as a transport medium for nutrients, hormones, and other substances. Corpuscles, or red and white blood cells, make up 45% of the blood and are responsible for transporting oxygen and fighting infection. SERUM is the liquid portion of the blood that remains after clotting has occurred. Platelets are small cell fragments that help with clotting and healing. All of these components are essential for the proper functioning of the human body.