Question

(a) How does the human body respond to an allergen ? Which type of antibody is produced during allergic reactions ?

(b) Name the types of drugs that help in reducing the symptoms of allergic reactions.

(c) Name the chemicals released in the body during an allergic reaction.

Hint:

On exposure to an allergen the body makes IgE antibodies. Mast cells release histamine and serotonin. Antihistamines reduce symptoms.

Answer 1

Step 1: Part (a): response to an allergen:
Allergy is an exaggerated response of the immune system to some foreign substances called allergens, such as pollen, dust or some foods.
On exposure, the body makes IgE type antibodies against the allergen.
These antibodies attach to mast cells in the tissues.

Step 2: Part (b): drugs that reduce symptoms:
The symptoms are treated with antihistamines. They block the action of histamine.
Adrenaline and steroids are also used. They quickly reduce the effects of the allergy.

Step 3: Part (c): chemicals released:
On later exposure, the allergen binds to the IgE on mast cells.
The mast cells then release histamine and serotonin.
These cause sneezing, watery eyes, rashes and breathing trouble.

Final Answer:
(a) The body makes IgE antibodies on exposure to the allergen. (b) Antihistamines, adrenaline and steroids. (c) Histamine and serotonin.