During an allergic reaction, binding of antigens to IgE antibodies initiates a response, in which ch

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7.Human Health and Disease

normal

During an allergic reaction, the binding of antigens to IgE antibodies initiates a response, in which chemicals cause the dilation of blood vessels and a host of other physiological changes. Such chemicals are

Interferons

Hormones

Histamines

acetylamine

Solution

Histamine is released from mast cells during allergic reactions. Histamine can occur in various tissues but is concentrated in connective tissue. It is formed from the amino acids histidine. It causes dilation and increases permeability of small blood vessels, which results in such symptoms as localised swelling, itching, sneezing and runny eyes and nose.

Standard 12

Biology