Monday, October 12, 2009
Blood is a bodily fluid which runs throughout a network of tube-like elastic vessels, distrubuting the necessary substances to the body cells, such as oxygen and nutrients, and transporting waste products away from those same cells. Blood is basically composed of three types of cells: 1) red blood cells, whose function is to carry nutrients, oxygen, and carbon dioxyde to and away from the body cells; 2) white blood cells, whose role is to protect the body from disease-inflicting foreign microorganisms such as bacteria, fungi, and viruses; 3) platelets, which are involved in hemostasis, causing blood to form clots at the site of a wound, stopping bleeding. These blood cells are suspended in plasma, which is composed of 90% water and 10% mineral ions, glucose, proteins, and hormones. The blood cells are produced in the bone marrow.