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9 Cards in this Set
- Front
- Back
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Autacoids
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- locally active hormones
- wide physiological and pathological role - histamine, serotonin, bradykinin, eicosanoids, and cytokines - released by different cell types in blood stream |
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Histamine
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- decarboxylation of L-histidine 2-(4-imidazoyl) ethyl amine - widely stored in mast cells
- wide/uneven storage - chiefly mast cells and basophils (bronchial & intestinal mucosae) - low turnover - low turnover in non-mast cells: Gastric mucosa,, CNS - high turnover |
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Anaphylaxis
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- severe allergic reaction that can involve multiple organs
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Postaglandins
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- causes Histamine to be released
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Histamine Receptors
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- H1 - higher affinity, rapid onset & decline
- H2 - slower, sustained - BP = fall |
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H1
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- Gq protein
- In bloodstream, smooth muscle, heart, CNS - increases vascular permeability, airway SM contraction, vasodilation, flushing, muscus secretion, pruritis |
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H2
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- Gs protein
- in gastic mucosa, heart, uterus, CNS - increases gastric acid secretion, resp. muscus secretion, nasal airway resistance, SM relaxation in lower airways |
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Histamine affects
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- dilation of blood vessels (H1)
- increased permeability of post capillary venules (H1) - adhesion molecules & leukocyte recruitment - edema - Heart - (H1) AVN - slows conduction, (H2) increase in rate and force - Neural - (H1) sensory nerve endings stimulant - inflammation - triple response |
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Histamine's classic effects (triple response)
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1. Red Spot - due to intense capillary dilation
2. Wheal - exudation of fluid from capillaries and venules 3. Flare - due to arteriolar dilation mediated by axon reflex |
