Allergic Responses

Allergic responses

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Allergens = a normally harmless substance with proteins that cause an immune response in someone who is allergic

Hypersensitivity = over reaction of the immune system in reaction to allergen exposure

In many people allergens do not produce allergic response, but in those with an allergy the allergens cause an over-reaction of the immune system. These people can be described as hypersensitive.

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Symptoms of an Allergy

Two types of symptoms:

Localised = affects only a specific region of the body

Anaphylactic shock = severe, whole body reaction. Is sudden and potentially fatal. Includes:

  • Odema (swelling) in the airways
  • Sudden fall in blood pressure

Can be so rapid and severe that death can be caused by inadequate blood circulation or asphyxiation.

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The Process of an Allergic Response

B cells = white blood cell produced in bone marrow and produce antibodies.

IgE antibodies = antibodies produced during an immune response.

Mast cells = cells of the immune system that produce histamine.

Histamine = chemical released when IgE antibodies bind to mast cells

When a person with an allergy is exposed to an allergen their immune system recognises it as non-self.

B cells then produce IgE antibodies - these antibodies belong to the immunglobin E group that are produced during immune response.

The IgE antibodies bind to mast cells which are found in all tissues

When the allergen binds to the IgE antibodies on the mast cell, histamine is released.

Histamine is what produces the symptoms of an allergy.

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