Biology Aids Essay Example | Topics and Well Written Essays - 1750 words

Biology Aids - Essay Example The two major cell types in blood are white blood cells and red blood cells. Red blood cells are the most common type of blood cells which functions as the principal means to deliver oxygen from the lungs to body tissues through blood. Adult humans have roughly 2-3 1013 red blood cells at any given time (women have about 4 million to 5 million erythrocytes per cubic millimeter (microliter) of blood and men about 5 million to 6 million. On the other hand, white blood cells are components of the blood. They are manufactured in the bone marrow and are instrumental in depending the body against infectious diseases and foreign substances. White blood cells are part of the immune system. In a normal adult, There are normally between 4x109 and 11x109 white blood cells in a litre of healthy adult blood - about 7,000 to 25,000 white blood cells per drop. B-cells circulate throughout the body with antibody molecules on their surfaces. When they pick up the signal of a particular antigen, they multiply and transform into plasma cells, which are essentially minifactories with one purpose: to churn out the precise antibodies that hook onto the antigens of the interloper. T-cells, on the other hand, migrate to the thymus. ... T-cells, on the other hand, migrate to the thymus. There, with the aid of various thymic hormones, immature T-cells grow, learn to recognize and attack antigens, and develop a range of specialized activities. The thymus is the master gland of cell-mediated immunity, a veritable training school for different classes of T-cells. There are three types of T-cells: T-helper cells which orchestrate the actions of other immune cells; killer T-cells which liquidate invading microbes, viruses or cancer cells; and suppressor cells which maintains properly balanced immune responses. 4. What does MHC stand for What is it Why is it important in the context of disease-causing agents MHC stand for major histocompatibility complex which is a group of genes that code for certain proteins that are found in the surface of cells and help the immune system recognize foreign substances. MHC is an essential component of the immune response as they allow the T-cells of the immune system to recognized body cells which are invaded by infectious substances. The MHC molecules do this by presenting fragments of proteins belonging to the invader on the cell's surface. The T cell recognizes the foreign peptide attached to the MHC molecule and binds to it, stimulating the T cell to either destroy or cure the infected cell. In uninfected healthy cells the MHC molecule presents peptides from its own cell, to which T cells do not normally react. 5. Compare and contrast viruses and bacteria. Both virus and bacteria both has the capacity to bring diseases. Also, both organisms contain DNA and enzymes. Amidst these similarities, a virus is smaller