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The first time an antigen (allergen) is encountered, the body becomes "sensitized" or forms antibodies, but no visible signs of hypersensitivity is exhibited.
1.) the allergen is encountered by mast cells and basophils, each coated with a particular group of antibodies that wsere formed during the first encounter
2.) then, chemicals such as histamine are released
3.) The severity of the reaction depends upon where in/on the body the chemicals are released
Tendency of allergies being inherited
at least one in five people have had or will have allergies related to hay fever (most common allergy)
Four principle types of hypersensitivities
Anaphylaxis reactions, cytotoxic reactions, immune complex reactions, cell mediated reactions,
occurs within a few minutes after a sensitized person is re-exposed to a particular antigen, certain chemical agents are released, which hekp to attract neutrophils and eosinophils to the area.
increases permeability and dilation of blood capillaries, resulting in edema, erythema (redness) increase mucus csecretion, and smooth muscle contractions.
slow-reacting substances that tend to cause prolonged contractions of certain smooth muscles ( asthma attacks)
affects smooth muscle of the respiratory system and can cause an increase in mucus secretion
upper res. system type 1
itchy and tearing eyes, congested nasal passageways, coughing and sneezing,
Lower res system type 1
asthma-like symptoms, wheezing and shortness of breath caused by constriction of smooth muscles in the bronchial tubes
Gastrointestinal tract type 1
certain food allergies can cause diarrhea, however, other factors are usually involved, some hives or may even lead to systemic shock.
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