# ECE_3820_Hw_6_answers - 225.7% change. d) Pumping work is...

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ECE 3820 Homework answers Hw Set #6 Ritter 4.3 a) Plot the pressure-volume loop (P (mmHg) vs V (mL)) using data from Fig 4.P1. b) Show where in the pressure-volume loop the following events occur: A-V valve closes, A-V valve opens, aortic valve closes, aortic valve opens, isovolumic contraction, isovolumic relaxation, ventricular filling, ventricular ejection. Indicate the end-systolic volume. c) Label the preload and afterload. d) Estimate the area under the curve. Work: 4550 to 6148 mmHg mL, Energy=5500 to 7407 mmHg mL/sec. e) Do not do this part. Ritter 4.4 a) 19.3% change b) 4.2 L/min before treatment, 5.4 L/min after treatment c) contractility before treatment was 1.75 mmHg/mL, contractility after treatment was 5.70 mmHg/mL.
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Unformatted text preview: 225.7% change. d) Pumping work is area under the solid curves. Work before: 10850 mmHg mL, Work after: 16200 mmHg mL. Ritter 4.14 Contractility is defined on a pressure volume curve as the slope of the left ventricular pressure volume points connected at end-systole after an experiment in which afterload is increased. Be able to draw this slope on a pressure volume diagram. Ritter 4.20 a) Power = 0.976 Watts b) Total metabolic energy = 11.16 Watts c) Change in pressure during isovolumic contraction is approx 90 mmHg. Transmural pressure difference is 89 mmHg. Use Laplaces equation for the heart (provided in the class slides) and a wall thickness of 1.5 cm to compute wall stress....
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## This note was uploaded on 11/14/2011 for the course ECE 3820 taught by Professor Wang during the Fall '11 term at GWU.

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