NURS 3550H Lecture Notes - Lecture 5: Laxative, Ataxia, Hypotension
28 Dec 2018
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Document Summary
Histamine is molecule produced in specialized cells through the body: has an important role in allergic reactions and regulation of gastric acid secretion, locally acting compound. Present in almost all tissues (esp. in skin, lungs, gi) Synthesized and stored in mast cells or basophils in the periphery: basophils are in the blood, mast cells are in the skin and other soft tissues. Must have prior exposure to the allergen for this cascade to take place. Several agents can act directly on mast cells to trigger histamine release. Histamine acts primarily through 2 receptors: h1 and h2. Vasodilation of arterioles and venules: prominent in skin of the face and upper body. Increased capillary permeability: due to endothelial cells contracting, fluid, protein, and platelets can escape, edema can occur, may cause drop in bp. Bronchoconstriction: however, histamines do not cause spontaneous asthma attacks, antihistamines are not used to treat asthma.
