In the circulatory system of the human body, there are about 5-6 quarts of blood in the average adult. This blood is considered a tissue because it has many cells. The blood goes to all the parts of the body taking oxygen from the lungs and carbon dioxide to the lungs, while also transporting metabolic wastes and nutrients. Blood is made up of a fluid called plasma. Plasma is 90% water, but has dissolved substances in …showed first 75 words of 477 total…

…showed last 75 words of 477 total…against pathogens and germs is known as phagocytosis. They fight infection by swallowing up and destroying the germs. Thrombocytes (platelets) vary in shape and size and are thought of as cell pieces because they don’t have a nucleus. A regular count of thrombocytes is 250,000 to 400,000 per cubic millimeter. They secrete a chemical called serotonin, which causes the blood vessel to spasm and narrow. The platelets are needed for blood clots and preventing blood loss.