Question

Explain what happens physiologically in a person that has been sensitized to an allergen and they encounter the allergen for the second time. Then compare and contrast the reactions that occur in the person between the first and second encounter of the allergen. Be able to explain what accounts for the differences.       

Answer 1

When the body encounters an allergen for the first time(first exposure), Type 1 hypersensitivity will occur whicch will cause only mild reactions.

Tcell activation will lead to the formation of interleukins .

The interleukins interacts with the B cells to form an specific type of antibodies, IgE.

this Ige binds to the IgE specific receptors on the mast cells and the basophils.The IgE cells are sensitized with the allergen.

When there is an exposure of the same allergen, the allergen can bind to the IgE molecules, which will cause activation of the mast cells and basophils, resulting in secretions of large amount of chemical mediators.

The chemical mediators will cause vigorous reactions in the body such as rhinorrhea, anaphylaxis.