HTHSCI 1H06 Lecture 2: Lecture 2 Summary Notes
11 Jan 2019
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For instance in the digestive system, smooth muscle of the intestines contracts, parietal cells increase gastric acid secretion, etc: response: there are 4 types of histamine receptors. Each is a 7 tmr (transmembrane receptor) in each case, the ligand must be recognized, the signal transferred, and a response elicited: h1 receptors: smooth muscle, endothelium, brain. Responds to allergic conditions: h2 r: gastric mucosa, cardiac muscle, mast cells, brain. Aids w. gastric acid secretion: h3 r: brain and neurons. Role in cns and sleep disorders, as well as pain: h4 r: immune cells (stimulate wbc"s and lymphocytes). Immune system and inflammatory/pain: termination: some histamine is taken into cells. Mostly, enzymatically degraded: diamine oxidase (extracellular histamine in intestines, kidney and placenta, histamine methyltransferase (intracellular histamine in kidney, liver, colon, pancreas, bronchi and cns, histamine plays a significant role in many physiological disorders.
