Lecture 8 02/17/2014
Autonomic nervous systemacetylcholine (Ach): acetic acid + choline(a nutrient in almost everything you
Neurons that makes choline=cholinergic
Neurons that act on receptors=cholinergic receptors; 2 types:
Mtype; muscarinic receptors (autonomic)
Ntype; nicotinic receptors (skeletal)
Cardiac musclemuscarinic receptors; metabotropic▯gproteins signaling pathways; intracellular response.
Pacemaker (modified muscle cells)cannot contract like a muscle, but they can spontaneously depolarize
themselves because they have sodium channels that can open when it’s repolarized▯depolarization
▯funny channel, and the funny sodium current: through gap junctions allow other cells to contract and
depolarizethe neuron ends in the pacemaker.
Muscarinicslows down the heart rate and decreases the blood pressure; in humans it cannot decrease the
strength of the heart but it can in some invertebrates.
Baroreceptor reflex: controls blood pressure. Increase blood pressureturn off sympathetic response▯turn
on cholinergic and then decreases the heart rate.
Bradycardia (slow heart rate) and tachycardia (fast heart rate)
Smooth muscle▯GI tract: increase motility; stimulatory
Airwaysbronchoconstriction (reflex mechanism)
Alveoli are delicate and allow for gas exchange; when something gets into the airway and potentially small
enough to get down to the alveoli it could damage and cause infection ▯so constrict the bronchiole so it
doesn’t get to the alveoli and WBC can attack the foreign object preventing infection. This is done by
muscarinic receptors by acetylcholine.
Use an antagonist of acetylcholine for treatment of asthma (blocks ACh)
Atropine (muscarinic receptor blocker)
“patent” airwaysopen airways
Eyes have cholinergic receptorsmuscarinic receptors causes constriction.
Pancreasstimulate insulin for digestion
Exocrine▯secretes material into a cavity, increases enzyme secretion into the intestine.
Endocrinehormone gland and releases into the bloodstream