BIOL 2P94 Lecture Notes - Lecture 7: Nicotinic Acetylcholine Receptor, Adrenal Medulla, Postganglionic Nerve Fibers
4 Feb 2013
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Document Summary
Peripheral autonomic nervous system: the sympathetic ns is distributed to more tissues than is the parasympathethic ns. The parasympathethic ns innervates glands and some thoracic and abdominal viscera. The parasympathethic ns is noticeably absent from all limb and body wall vasculature. Nss tend to have opposite effects on dually-innervated effector tissues. Analogous to muscle agonist/antagonist pairs, symp/parasymp are reciprocally coordinated. Example of symp/parasymp effects on cardiac pacemaker cells. Vagal (parasymp) stimulation immediately depol. rate and hyperpol. the cell. Mediated by ach: na and ca influx and k outflux. Symp stimulation causes in depol. rate and heart rate after a few seconds. Mediated by ne: na and ca influx only. Actions of autonomic nxt are conferred by nature and location of the nxt"s receptors. There are 5 types of muscarinic receptors, including m1 (ganglia), m2 (heart), m3 (smooth muscle, secretory glands) There are nicotinic receptors as well (ganglia, adrenal medulla) B receptors cause contraction of vascular smooth muscle via plc/dag/ca pathway.
