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BIO210-Lecture 29-heart & heartbeat.docx

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Robert Reisz

Lecture 29- the human heart and the heartbeat  Slide 3 o Diagram shows one cardiac cycle  Slide 4 o These are heart muscle cells o Nodal tissue is specialized muscle cells  Slide 5 o Intercalated discs hold the muscle cells together and form muscle layers of the heart (atria, etc) o Gap junctions allow coordination of many cells all together o Calcium is very important in heart muscle tissue; comes from sarcoplasmic reticulum, from outside the cell, and from one other  Slide 6 o Allows heart to beat in coordinated manner o Heart constantly using energy o Automaticity—will automatically produce a heartbeat b.c of its nodal tissue o Nodal tissue has properties of muscle o Every time a muscle has an action potential, it contracts o SA-pacemaker? o AV allows info to be captured in atria and passed to ventricle o Purkinje fibers sends electric energy o This nodal tissue, if cut into little tissue, all of these would spontaneously depolarize (create an action potential)  Slide 7 o When threshold depolarization occurs, we get this potential; like an action potential in nodal celss and will sweep across atria cells b.c they have gap junctions o Septum separates 2 atria from 2 ventricles o Has unstable rustic* potential*  Slide 8 o Decrease in
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