BIOL 1344 Lecture Notes - Lecture 6: Interventricular Septum, Sinus Rhythm, Purkinje Fibers
14 Sep 2016
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Pace maker cells: 1% of all cells. Myocardial cells [cardiomyocytes]: 99% of all cells. Sino-atrial node [sa node]: posterior wall of right atrium. Responsible for sinus rhythm; heart rate: 70 bpm. Striated- sarcomeres > actin + myosin filaments > sliding of filaments > force. Mitochondria, glucose, ff, lactic acid, ketones used to generate force. Blood is squeezed out of heart; wringing action. Can sometimes close if there is acidity, no o2 > no atp. Pacemaker cells: excitable > action potential > reverse of polarity. Depolarization > action potential > triggers ap in muscle cells > triggers muscle contraction. *** look at diagram of action potential on slideshow. B= slow ca2+ entry through voltage-gated ca2+ channels. C= k+ efflux (out) through voltage-gated k+ channels. Sa node > atrial muscle cell > av node > bundle of his, rt. > epinephrine > binds to beta1 receptors >heart rate increases > chronotropic effect [change in heart rate]
