BISC306 Lecture Notes - Lecture 2: Heart Rate, Skeletal Muscle, Cardiac Muscle Cell
23 Oct 2017
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Document Summary
Vertebrate hearts: hearts are composed of mostly cardiac type muscle, contractions are elicited by action potentials, myocytes are electrically coupled via gap junctions. The mammalian heart the heart has 4 muscular chambers: 2 atria, 2 ventricles the heart beat is myogenic with pacemakers located in sino atrial (sa) and. This is called diastole: a chamber ejects blood when the muscle contracts. This is called systole. cardiomyocytes are striated and electrically coupled by gap junctions. More about pacemakers: many invertebrates have neurogenic pacemakers, composed nervous tissue which acts as a central pattern generator, autorhythmic, however, the rhythm can be modified by the cns and hormones, vertebrates and some invertebrates have myogenic pacemakers. Comparison of cardiac and skeletal muscle action potentials: the long plateau phase ensures that contraction of cardiac muscle cannot summate as can occur in skeletal muscle, example- cardiac muscle can only twitch.
