Now the average adult has about five liters of blood flowing inside his body. Blood is the fluid of life growth and health. It transports oxygen from the lungs to body tissue and carbon dioxide from body tissue to the lungs. It transports nourishment from digestion and hormones from glands throughout the body. It transports disease, finding substances to tissues and waste to the kidneys. Blood is alive because it contains living cells. Red blood cells and white blood cells are responsible for nourishing and cleansing the body. Since the cells are alive, they need nourishment Vitamins and minerals keep the blood healthy blood cells have a definite life cycle, just as all living organisms do. Approximately fifty five percent of blood is plasma. A strong colored clear liquid plasma carries the solid cells and platelets when the human body loses a little bit of blood through a minor wound. The blate let's help the blood clot so that the bleeding stops. You would bleed to death without the platelets. Your body is always making new blood inside your bones. When the human body loses a lot of blood through a major wound, that blood has to be replaced through a blood transfusion from other people. But everybody's blood is not the same. There are four different blood types plus your body has rh factors which make it even more unique. Blood received through a transfusion must match your own. Sometimes patients donate their own blood when they are scheduled to have major surgery so that they will have a perfect match. It is called an auto longest blood donation.