Question | Answer |
allergic reaction or an abnormal reactions characterized by an excessive reaction to a particular stimulus | hypersensitivity |
Hypersensitivity disorders include | allergy, autoimmune, isimmunity |
allergy | antigen is an exogenous agent |
autoimmunity | antigen to self |
isimmunity | antigon is from tissue or another individual. |
4 types of hypersensitivity mechanisms | IgE mediated, tissue specific, Immune complex mediated and cell mediated. |
Type I-IgE mediated is the most common | antibodies that coat mast cells signalling them to degranulate followed by discharge of chemicals such as histamine, |
Type II - Tissue specific | Antibodies bind to the antigen on the cell surface. think transfusion gone wrong- wrong blood given. |
type III- Immune complex mediated | antibodies bind to soluble antigens that were released into the body fluids and the immune complexes are deposited into the tissue. |
Type IV- cell mediated | cytototoxic T lymphocytes or lymphokines that produce TH1 cells (T helper cells) attack & destroy cellular targets directly. |
Type I hypersensitivity | Allergic reactions are IgE mediated. |
Type 1 hypersensitivity is | humoral and immeadieate |
In Type 1-first exposure to allergen leads to | development of IgE antibodies from B lymphs that attach to mast cells and basophils in tissues = sensitization |
In type 1 subsequent exposures (following first exposure) | allergen attaches to IgE antibody on mast cell releasing histamine leading to inflammation & edema |
Type 1 anaphylatic shock | large amounts of chemicals released from mast cells causing severe reactions. |
Type 1 anaphylatic affects systemically | systemic vasodilation leads to severe decreased BP and loss of fluids |
Type 1 anaphylatic affects lungs | by bronchconstriction leading to hypoxemia |
Treatment for anaphylatic rxn | Benedryl, epinephrineo |
What does benedryl do? | it is an anti-histamine- blocks response to release histamine |
epinephrine opens airways via | bronchodilation, decreases mucus production |
epinephrine increases BP via | vasoconstriction which reverses the effects of histamine. |