Evolution Of Immunity And The Invertebrates :: essays research papers

Evolution of impedance and the Invertebrates"Article Summery" Name "Immunity and the Invertebrates" Periodical ScientificAmerican Nov, 1996 Author Gregory Beck and Gail S. Habicht Pages 60 - 71 TotalPages Read 9     The complex immune systems of humans and other mammals evolved over sort of a long time - in some rather surprising ways. In 1982 a Russian zoologistnamed Elie Metchnikoff noticed a unique airplane propeller of starfish larva. When heinserted a foreign determination through its membrane, tiny cells would try to ingestthe invader through the process of phagocytosis. It was already known thatphagocytosis occurred in specialized mammal cells but never in something lesscomplex like a starfish. This discovery led him to understand that phagocytosisplayed a oftentimes broader role, it was a fundamental mechanism of protection in theanimal kingdom. Metchnikoffs further studies showed that the host defensesystem of all animals today were present millions of years earlier when hey werejust beginning to evolve. His studies opened up the new field of comparativeimmunology. Comparative immunologists studied the immune defenses of past andcurrent creatures. They gained further insight into how immunity works.     The most basic requirement of an immune system is to distinguish betweenones own cells and "non-self" cells. The second job is to eliminate the non-self cells. When a foreign object enters the body, several things happen. Bloodstops flowing, the immunity system begins to eliminate unwanted microbes withphagocytic white blood cells. This defensive mechanism is possessed by allanimals with an innate system of immunity. Innate cellular immunity is believedto be the earliest form of immunity. Another form of innate immunity iscomplement, composed of 30 disparate proteins of the blood.     If these mechanisms do not work to defeat an invader, vertebrates relyon anoth er response acquired immunity. Acquired immunity is mainly dealt byspecialized white blood cells called lymphocytes. Lymphocytes pilgrimage throughoutthe blood and lymph glands waiting to attack molecules called antigens.Lymphocytes are made of ii classes B and T. B lymphocytes release antibodieswhile T help produce antibodies and allot to recognize antigens. AcquiredImmunity is highly effective but takes days to activate and succeed because ofits complex nature. Despite this, acquired immunity offers one great feature immunologic memory. Immunological Memory allows the lymphocytes to recognizepreviously encountered antigens making reaction time faster. For this reason, wegive immunizations or booster shots to children.     So it has been established that current vertebrates have two defensemechanisms innate and acquired, but what of older organisms ? Both mechanismssurprisingly enough can be found in almost all organisms (specifically