PHGY 210 Lecture Notes - Lecture 14: Aldosterone, Baroreflex, Mechanoreceptor
25 Feb 2013
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The parasympathetic control of the heart rate, medulla oblongata to a ganglion, through acetylcholine transduction, nicotinic receptor. Post-ganglionic nerve transduce ach onto s. a. node cells, muscarinic receptor. Atropine will collect at the clefts between s. a. nodes and post-ganglionic nerve cells, will speed up heart rate as parasympathetic system control is removed. Sympathetic control of the heart rate is controlled by acetylcholine and then norepinephrine at the beta-adrenergic receptor. Beta-agonist would speed up the heart rate by making it more sensitive, an antagonist would competitively bind. If norepinephrine is dumped on the ventricular muscle would increase calcium inflow like on the s. a. nodes and increase contraction force. Sympathetic contractions do not follow the normal edv/sv ratios, they have their own curves. Most of the vessels in the bodies (all the way down to venules and arterioles), are controlled by the sympathetic vessels, using an alpha-adrenergic receptor. Activation would lead to constrictions of the vessels.
