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Phagocytosis and the Immune Response

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Phagocytosis and the Immune Response Contents Introduction....................................................................................3 Phagocytosis Leucocytes Neutrophils Oxidative burst Body..........................................................................................4 - 6 Macrophages Natural immunity - specific/non-specific Lymphocyte Antibodies Antigens B cells Conclusion.................................................................................6 - 7 T cells Cell mediated immune response Bibliography .............................................................................. 7 What are the roles of leucocytes in Phagocytosis and secretion of antibodies? The roles of cellular components of the blood are vital in the transport of respiratory gases and in the defence against disease. The role of white blood cells (also known as leucocytes) are concerned with the defence of the body against disease. Leucocytes are nucleated cells present in the blood. They are less numerous in comparison to red blood cells: there are around 7000 per nm� of blood compared with 5000000 red cells. There are three main types of leucocytes; these are neutrophils and monocytes, which carry out the process of Phagocytosis, which involves engulfing, and destroying the bacteria. Lymphocytes are the third and they secrete antibodies and help form part of the body's immune system. One of the functions of lysosomes is to digest material taken into the cell body by the process of Phagocytosis. Once a white cell has left the blood vessel and migrated to the enemy, the next job is to eat the microbe. ...read more.


Specific immunity The specific immune system protects the body from 'invasion' from microorganisms and parasites and also makes sure that the bodies defences do not turn on its own tissues. The specific immune response is made up from two different systems that cooperate closely: 1) Hormonal immunity - also called antibody-medicated immunity, involves only chemicals, called antibodies, attack bacteria and viruses before they get inside body cells. They also react with toxins and other soluble foreign proteins. Antibodies are produced by white cells called B-Cells. 2) Cell-mediated immunity as the name suggests, involves cells, which attack foreign organisms directly. Activated T-Cells kill some micro-organisms, but they mostly attack infected body cells. Cell mediated immunity is used by the body to deal with multicellular parasites, fungi, cancer cells. B-Cells are produced in the bone marrow and are distributed throughout the body in the lymph nodes. B-cells respond to the foreign antigens of a pathogen by producing specific antibodies. Antibodies are complex proteins that are released into the blood and carried to the site of infection. B-cells do not fight pathogens directly. Antibodies interact with the antigen and render it harmless. Reference: Markus Barbor - 2000 - Biology When attacked by disease-causing organisms, the body retaliates by waging biochemical's warfare. ...read more.


Memory cells may remain in the body for many years, the production of antibodies by B cells is referred to as the humoral immune response. Reference: John Adds - 1999 - Respiration and coordination T cells undergo maturation in the thymus gland and then pass to the lymph nodes and spleen. T cells can also recognise antigens by means of specific receptors and, once activated by a specific antigen, they undergo mitotic divisions to produce clones of T cells, with different functions. Name Function Killer T cells Can attach themselves to invading cells and destroy them; they also attract macrophages and help to activate Phagocytosis. Helper T cells Help the humoral response by involvement in the maturation of B cells and by triggering the production of antibodies by the B cells. Memory T cells Work in the same way as the memory B cells, ensuring a rapid response on subsequent exposure to the same non-self antigens. Suppressor T cells Regulate the immune system response by suppressing the activity of the killer T cells. The response made by T cells is referred to as the cell mediated immune response. Killer T cells cause cells infected with the virus particles to lyse. T cells in the thymus gland, sometimes referred to as thymocytes manufacture and release molecules called lymphokines, which include interferon. Interferon prevents the replication of the virus. ...read more.

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