BIOL 1119 Lecture Notes - Lecture 3: Internal Carotid Artery, Cardiac Output, Medulla Oblongata
3 Oct 2017
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Document Summary
Sympathetic nervous system: sympathetic nerves secrete norepinephrine, which binds to -adrenergic receptors in the heart. Ne and epi in the blood stream can bind to b receptors. Binding activates the camp 2nd messenger system in nodal cells and cardiocytes. Ca2+ channels in the plasma membrane of cardiocytes more quickly: activate receptor on ca2+ channel in the sr in order to open ca2+ channels on the sr of cardiocytes more quickly. In the sa node, opening more special sodium channels leads to an increased influx of sodium per unit time. This means that threshold voltage is reached more quickly: start of the next depolarization phase in the sa node occurs more quickly increases heart rate. In cardiocytes, opening more calcium channels on cell surface and on sr means more calcium enters from outside cell and more calcium from inside sr per unit time. This means we reach a positive membrane potential more quickly increases speed of depolarization of cardiocytes.
