Tuesday, May 13, 2008

White Blood Cells

White blood cells, or leukocytes, detent the body against foreign organisms. They are almost colorless, are considerably larger than red cells, have a nucleus, and are much less numerous; only one or two exist for every 1,000 red cells. The number increases in the presence of infection.

There are three types; granulocytes, lymphocytes, and monocytes. Granulocytes, accounting for about 70 percent of all white cells, include neutrophilis, ensinophils, and basophils. They are formed in the bone marrow. Lymphocytes form primarily in the Speen and lymphnodes. Monocytes are believed to originate from lymphocytes.

Platelets, or thrombocytes, are tiny bits of cytoplasm, much smaller than the red blood cells but lacking a nucleus. They are round or biconcave disks and are normally about 30 to 40 times more numerous than the white blood cells. They are produced as broken fragments of the megakaryocytes. The plateletss' primary function is in the clotting process described below.

Plasma is a complex, colorless solution, about 90 percent water, that carries different ions and molecules, including protein, enzymes, hormones, nutrients, waste materials such as urea, and fibrinogen, the protein that aids in clotting. The most abundant plasma protein is albumin, which normally keeps a large portion of the body water in the blood. When the plasma albumin concentration becomes dangerously low, because of disease, free water collects in the tissues outside the blood vessels, producing swelling called edema.

Globulin are large protein molecules of many chemical structures and functions. The antibodies, produced by lymphocytes, are globulin and are carried throughout the body, where many of them fight bacterial or viral invasion. Other antibodies are related to the blood groups.

An important function of plasma is to transport nutrients to the tissue. Glucose, absorb from the bowels, constitutes a major source of body energy. Some plasma proteins and fats are also used by the tissue for cell growth and energy. Minerals essential to body function, although present only in trace amounts, are important elements of the plasma.
Post a Comment