WHAT IS BLOOD ?

Blood is made of four components:

	Plasma is a mixture of water, sugar, fat, protein, and potassium and calcium salts. It also contains many chemicals that help form blood the clots necessary to stop bleeding. More than 92% of plasma is water.
	Red blood cells contain a special protein called hemoglobin, which carries the oxygen we inhale with our lungs to all of the parts of our bodies. It then returns carbon dioxide from our body to our lungs so we can exhale it. Hemoglobin is also responsible for making red blood cells red. We have so many red blood cells that our blood itself appears red, even though it contains more than red blood cells.
	White blood cells are clear round cells that are bigger than red blood cells. White blood cells produce proteins called antibodies that help our bodies fight infections caused by bacteria, viruses, and foreign proteins.
	Platelets aren't really cells at all; they are just fragments of cells. When we are injured, platelets gather at the site of the injury and stick to the edges of the wound. They release chemicals that help start the process of blood clotting so that bleeding will stop.