Human Immune System Essay Example for Free

Human Immune System Essay None of these things are able to get in when your immune system is working, but the moment your immune system stops the door is wide open. Once you die it only takes a few weeks for these organisms to completely dismantle your body and carry it away, until all thats left is a skeleton. The human immune system is made up of a number of interdependent cell types which collectively protect the persons body from various parasitic, fungal, bacterial and viral infections, as well as from the growth of tumor cells. | A number of these cell types have specialized functions, are able to kill parasites, engulf bacteria, or kill tumor cells or viral-infected cells. Frequently, these cells are dependent upon the, T, helper subset for activation signals in the form of secretions which are more formally referred to as, Lymphokines, Cytokines, or specifically as, Interleukins. An understanding of the T helper subset may assist in comprehension of the root of immune deficiencies, as well as perception of the potential avenues that the human immune system can be modulated in the case of particular diseases. Immune Response The presence of an APC, combined with a T cell or B cell, is required in order for there to be an immune response to a foreign antigen. Should an APC present an antigen on its cell surface to a B cell, for example, the B cell is signaled to proliferate and produce antibodies. The antibodies then specifically bind to that antigen. If the antibodies bind to antigens on parasites or bacteria, it acts as a signal for macrophages or PMNs to engulf and kill them. One addition and important function of antibodies is to start something referred to as a, Complement Destruction Cascade. When antibodies bind to bacteria or cells, serum proteins referred to as, Complement, first bind to immobilized antibodies, and then destroy the bacteria through creating holes in the bacteria. Antibodies may also signal macrophages and natural killer cells to kill bacterial infected cells or viral cells. Aids The fight between the virus and the immune system for supremacy is continuous. Our b ody responds to this onslaught through production of more T-cells, some of which mature to become helper T-cells. The virus eventually infects these targets and eliminates them, too. More T-cells are produced; these too become infected, and are killed by the virus. This fight may continue for up to ten years before the body eventually succumbs, apparently because of the inability to any-longer produce T-cells. This loss of helper T-cells finally results in the complete inability of our body to ward-off even the weakest of organisms (all kinds of bacteria and viruses other than HIV) which are normally not ever a problem to us. This acquired condition of immunodeficiency is called, AIDS.