Heart Pump

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Heart Pump

Lecture number:
Lecture Note
University of Southern California
Bisc 307l - General Physiology
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BISC 307L 1st Edition Lecture 26 Current Lecture  Pressure-Volume Changes in Left Ventricle o o Summary of everything o Focuses on the left ventricle o Plot of the pressure in the left ventricle and the volume o A: the left ventricle has completed its relaxation and has not yet begun to refill- pressure at a minimum. And volume at a minimum because after ejection phase o B: the ventricles start to fill – increase volume (flat part due to the fact that the blood is trickling) No change in pressure. At the end the pressure does go up a little due to the atrium contracting for the final bit of filling. End diastolic volume o C: Volume is the same but the pressure increases. This is when the ventricle is contracting and the AV closes so pressure goes up. The valve going out to the artery is still closed so this pressure goes up. Isovolumic ventricular contraction phase (phase 3). Then the pressure exceeds the pressure in the artery so the valve opens and the ventricle ejects blood into the aorta o D: At the end of contraction (end systolic volume) when the blood is ejected out of the ventricle- this is also called the stroke volume at the end). Now start of relaxation of the left ventricle and the pressure falls and the semilunar valve closes and there is a vertical drop- this is isovolumic- because the AV valve is still closed so there is no change in volume  Wiggers Diagram o o correlates mechanical and electrical events during the cardiac cycle o go through it on your own besides the very top o can understand everything below the ECG  Cardiac Output/ Regulation of Heart Rate

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