What Is Non Specific Defence

Mammalian defence against infectious disease can be non-specific, otherwise known as innate, or specific (adaptive).

Non-specific defence can be further categorised into external (preventive) or internal (defensive). Innate defence can be physical, chemical or biological. The skin, commensal organisms (e.g. bacteria), mucous membranes and hair contribute to the physical mechanism of the body’s non-specific defence against disease. These prevent disease from entering the mammal’s body by acting as a physical barrier. Cilia which line the airways, as well as sweeping cells in the lungs and urinogenital tract, play a role in the non-specific defence. Cilia push pathogen-containing mucous out of the body. The acid of the stomach is an example
The inflammatory response is another non-specific mechanism of defence. This occurs when an area of tissue becomes damaged. Histamine is released from damaged/infected mast cells of the affected tissue causing a localised increase in blood flow by dilating arterial vessels and narrowing the venule vessels. This increases the movement of cellular response. Platelets and clotting factors of the blood migrate to the injury site to heal the wound and confine infectious agents to the site. This hinders the spread of the pathogen throughout the body. Cells surrounding the injury site release chemical signals called chemokines. These will be in higher concentrations closer to the injury site. This allows a “route” for phagocytic cells to migrate to the area of infection. Symptoms of the immunological response include redness of the infected area (accounted for by increased blood flow), fever and the area may appear swollen. Pus from the wound is formed from the phagocytic white blood cells which were involved in the engulfment of pathogens. When the infection has been successfully destroyed, histamine levels will subside and blood vessels return to their original
Immunodeficiency is when the immune system’s ability to fight against disease is compromised. This occurs when one or more components of the immune system are inactive. This can result in the recurrence of disease, slower healing time and an increase in the incidence of some cancers. Immunodeficiencies can be categorised into primary or secondary. A primary immunodeficiency disease is when an individual is born with a deficiency or has a genetic cause. A secondary immunodeficiency disease is the result of an external factor such as radiation. AIDS and leukaemia are examples. Autoimmunity is an abnormality in which the immune system is hyperactive and attacks the body’s own tissues. An example of an autoimmune disease is rheumatoid arthritis. This disease causes chronic joint inflammation as a result of the immune system attacking tissues around the joints. Symptoms of rheumatoid arthritis include pain of the joints, swollen joints and limping. There are four types of hypersensitivity. Type 1 hypersensitivity is an allergic reaction in result of exposure to an allergen. This is mediated by Immunogloblin