Breifly explain the various types of disorders arising from improper function of the immune system.

Explanation

Immune system disorders are :- (a) Autoimmunity. Sometimes the immune system of the body goes off the track and starts behaving against the ‘own body. or .self.. This leads to a variety of diseases known as autommune diseases. When the cells acting as antigens in the same body, they are called autoantigens. The nature of autoimmune diseases depends on the autoantigens involved. For example, chronic anaemia (myasthenia gravis) if the autoantigens are muscle cells, then it results in the destruction of its own muscles resulting in severe weakness, chronic hepatitis, addison.s disease, ulcerative colitis and rheumatoid arthritis.
(b) Severe Combined Immuno Deficiency (SCID). Sometimes newborn children are without T-cells and B-cells. These children are highly susceptible to various infections. Such children are highly susceptible even to minor infections. In developed countries like USA such children are kept alive by keeping them in germ-free environments :alled isolation suits.
(c) Anaphylactic Shock. It is an allergic reaction .involving all the `"tissues"//"parts"` of the body and occurs in a few minutes after the injection of an antigen such as penicillin. Such a reaction is very serious. Hislamine released from ruptured mast cells causes marked dilation of all the arteries so that a large amount of fluid is passed from the blood to the tissues and there is a drastic fall in blood pressure. The affected person may become unconscious and the individual may die within a short time.
(d) Allergy. Allergy is the hypersensitiveness of a person to some foreign substance coming in contact with or entering the body.
The substances that cause allergic reaction are called allergens. The common allergens are dust particles", pollen, fungal spores, fabrics, feathers, fur, bacteria, foods, heat, cold, sunlight etc. The symptoms that result from an allergy may be of different kinds but mostly it affects the skin and mucous membranes. Hay fever affects the mucous membranes of the nose, eyes and upper respiratory tracts. In asthma, the lower portions of the respiratory system are severely affected. In eczema the skin becomes red, followed by the appearance of minute blisters. Eczema may affect any pan of the body and is one of the most severest of all allergic symptoms.