Question

what is allergy?

Please tell
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Answer 1

Answer:

A damaging immune response by the body to a substance, especially a particular food, pollen, fur, or dust, to which it has become hypersensitive.

Answer 2

An allergy is an exaggerated reaction of the body's immune system to a particular food or substance which is generally harmless to most of the people.

Allergy can also said to be hypersensitivity of the body's immune system to a specific substance.

• Allergy symptoms occur when the immune system overreacts and triggers a reaction to something that is harmless.
• The substances that cause cause allergy are called allergens. The common allergens are pollen grains, dust, feathers, fungal spore, peanuts, mushrooms and mites in dust etc.
• The allergic reactions are usually very rapid and start appearing with the few minutes.
• Immune system responses can be mild, from coughing and running nose, to a life-threatening reaction known as anaphylaxis.

Reaction in the body during allergy

• The immune system of our body has lymphocytes, a type of white blood cells that defend the body against any foreign germ or antigen (or allergen which cause allergy) that enter our body. They recognise an antigen and produce antibodies which are specific to that antigen. These antibodies attack the antigens and form antigen-antibody complexes and reactions.
• During allergy, the immune system recognises an urgent such as a pollen grain, (mostly a harmless substance) as a foreign antigen, as a threat to the body. This triggers an antigen-antibody reaction. This reaction occurs on the membrane of special cells called the mast cells which become permeable and burst.
• Mast cells release chemicals called histamines which cause dilation of blood capillaries, redness and itchiness of skin and inflammation of membranes.
• Generally the first exposure to an allergen does not cause allergy and helps in the formation of antibodies only. But the second or subsequent exposures cause strong allergic reactions.
• Anti-histamine drugs quickly reduce and nullify the symptoms of allergy.
• Eosinophils, a type of blood cells also increase in number during allergic reactions and thought to have anti-inflammatory responses due to absorption of histamines.