Immunity
Animal immune response to pathogenic micro-organisms
The activation of the animal immune system or immune response takes place in 3 distinct consecutive steps.
Firstly we have the mechanical barriers such as the skin, stomach acid, cilia and mucus in order to try and stop pathogens from entering the body.
Secondly we have the body’s general or non-specific response to any particles that enter the body through a wound or any natural orifice. After the pathogen has passed through the first defence, complement activation will occur and activate responses that will cause inflammation (increased blood flow to capillaries and capillary permeability) caused by release of histamines and phagocytosis (the process of engulfing and destroying micro-organisms by phagocytes) in order to try and get rid of the pathogen. Histamines are organic molecules released by damaged tissue made from the base structure of ammonia and are the decarboxylated form of histidine. In most cases this is successful and the pathogen is eliminated.
The Third line of defence involves cells called lymphocytes which can be classified as two different types, namely B-lymphocytes (found in the blood and lymph but made in the bone marrow) and T-lymphocytes (made in the liver or bone marrow). They provide specific immune response using 2 parts. Humoral immunity and cell mediated immunity.
Humoral immunity (done by B-Lymphocytes) focuses on identifying pathogens and recognising antigens prior to cell infection. This is done by recognising the antigens on the germs surface, while cell mediated immunity (done by T-Lymphocytes) focuses on the active destruction of infected or cells using the antibodies produced using the antigens.
The B-Lymphocytes are made up of two types of cells, memory cells and plasma cells. The memory cells remember the specific type of antigen on the pathogen for the next time the organism is infected so a quick response is achieved, while plasma cells...