Blood Blood is made up of four components: plasma, red blood cells, white blood cells, and platelets. Most materials transported in the blood travel in the plasma. Plasma is the liquid part of the blood. Water makes up 90 percent of plasma. The other 10 percent is dissolved materials. Protein molecules give plasma its yellow color. There are three groups of plasma proteins. One group regulates the amount of water in the blood. Second group produces white blood cells and helps fight disease. Third group interacts with platelets to form blood clots.
Red Blood Cells Without red blood cells, your body could not use the oxygen that you breathe in. Red blood cells take up oxygen in the lungs and delivers it to the cells elsewhere in the body. A red blood cell is made mostly of hemoglobin which is an iron- containing protein that binds chemically to oxygen molecules. Hemoglobin also picks up some of the carbon dioxide produced by cells. Mature blood cells have no nuclei. Without a nucleus, a red blood cell cannot reproduce or repair itself. Mature red blood cells only live for about 120 days. Every second, 2 million red blood cells in your body die, but your bone marrow produces new blood cells at the same rate.
White Blood Cells Like red blood cells, white blood cells are produced by bone marrow. White blood cells are the body’s disease fighters. There are fewer white blood cells than red blood cells and white blood cells are larger than red blood cells. White blood cells contain nuclei and they can live for months or even years.
Platelets Platelets are cell fragments that play an important part in forming blood clots. When a blood vessel is cut, platelets collect and stick to the vessel at the site of the wound. A scab is a dried blood clot on the skins surface.
Blood Types A blood transfusion is the transfer of blood from one person to another. The marker molecules on your red blood cells determine your blood type and the type of blood that you can safely receive in transfusion. If you ever receive a transfusion your blood will be check first.
The Lymphatic System The lymphatic system is a network of vein-like vessels that returns the fluid to the bloodstream. This system acts something like rain gutters after a rain storm, carrying the excess fluid away. Once the fluid is inside the lymphatic system is called lymph. Lymph consists of water and dissolved materials such as glucose. It also contains some white blood cells. As lymph flows through the lymphatic system, it passes through small knobs of tissue called lymph nodes. The lymph nodes filter lymph, trapping bacteria and other disease causing microorganisms in the fluid.