BME 410 Lecture Notes - Lecture 9: Cardiac Muscle, Skeletal Muscle, Stroke Volume
20 Apr 2016
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Document Summary
Action potentials originate at the sinoatrial node and spread to ventricle: autonomous. Systole phase: tricuspid and mitral valves are closed: operates for billions of cycles, high strain (20%, fast actuation (1-10 hz, high force (1n, powered by chemical energy. Contract using atp and ca2+, bringing z disks closer together. Action potentials induce contraction: influx of ca2+ is also needed, ventricle is an electrochemical syncytium, allow ions to freely move between adjacent cells. Diastole phase: pulmonary and aortic valves are closed. Left ventricular ejection fraction = (stroke volume = end diastolic volume end systolic volume)/(end diastolic volume: end systolic volume is smaller than end diastolic volume. Blood vessels that vascularize the ventricles: branch off aorta, major arteries located on the surface of the heart, smaller arteries and capillaries penetrate into the muscle. Even if a patient survives a myocardial infarction, heart is permanently damaged (cid:2) (cid:2) (cid:2: heart failure, arrhythmias, fibrillation. Abnormal electrical circuits due to damaged heart muscle.
