BIOC34H3 Lecture Notes - Lecture 5: Adenylyl Cyclase, Beta Blocker, Sympathetic Nervous System
Document Summary
Everything that is happening i. e. influx of ions + depolarization, occurs at a much faster rate than normal bc of the sympathetic stimulation. Parasympathetic mechanisms: slows down rate of depolarization & heart rate, signal from brainstem cardiac branch of vagus nerve release ach on pacemaker cells. Needs regulation so heart rate does not go too high. Without regulation, it would become 100-110 bpm. Tone/input from sympathetic ns is more powerful than from parasympathetic but mostly, parasym can predominate sym due to regulation and leading to a lower heart rate. *symp activates b and a adrenergic receptors* (more beta than alpha bc alpha more common in blood vesseels) Atropine: block muscarinic r"s increase heart rate. Atenolol (aka beta blocker): block adrenoceptors slows down heart rate. Comparing the slowed/increased heart rate from the drug to the resting hr without the blockage, can measure amount of parasym and sym tone in heart.
