PHIL 2130 Lecture Notes - Lecture 25: Reflex Bradycardia, Baroreflex, Anaphylaxis
6 May 2020
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Vessels of skin and nasal mucosa express a1 receptors. Contract pupillary radial (dilator) muscles: mydriasis increase pupil d. Activation has diverse effects: include decrease in systemic bp. Expressed in the heart: positive inotropy and chronotropy. B2 and a1 receptors leads to variable effects on peripheral resistance. Cause significant vasoconstriction due to a1 agonism and low affinity for b2. Increases heart rate due to b1 agonism. Rapid infusion can result in baroreflex-induced bradycardia. Epipen: treatment of anaphylactic shock (bronchospasm, mucous membrane congestion, severe hypotension. Increased hr and inotropy due to direct b1 effect and indirect baroreflex-induced tachycardia. Alpha 1 + 2 agonist topically used as a decongestant spray. Antihypertensive: long duration of action b/c mechanism involves cns. Treat congestive heart failure (chf) postmyocardial infarction. Low affinity for b2 ensures little decrease of peripheral resistance (impt. Treatment of asthma by inhalation (reduce system side effects: tachycardia, skeletal muscle tremor)
