{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

quiz1_solutions

# quiz1_solutions - Harvard-MIT Division of Health Sciences...

This preview shows pages 1–4. Sign up to view the full content.

Harvard-MIT Division of Health Sciences and Technology HST.542 J : Quantitative Physiology: Organ Transport Systems Instructors: Roger Mark and Jose Venegas MASSACHUSETTS INSTITUTE OF TECHNOLOGY Departments of Electrical Engineering, Mechanical Engineering, and the Harvard-MIT Division of Health Sciences and Technology 6.022J/2.792J/BEH.371J/HST542J: Quantitative Physiology: Organ Transport Systems QUIZ 1 SOLUTIONS

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Problem 1 A. Draw normal P ( t ) waveforms for the left ventricle, left atrium, and aorta. Show two com- plete cardiac cycles, and use typical normal values for the pressures. Use the time axis provided in Figure 1.1a, and assume a heart rate of 60 bpm. C.O. = ˙ V O 2 C A O 2 C V O 2 = 363 ml O 2 /min ( 200 14 . 5 ) ml O 2 /liter blood = 363 55 = 6 . 6 L/min So SV = 6 . 6 L/min 60 beat/min = 110 cc/beat (See Figure.) B. The cardiac output was measured using the Fick method. Oxygen uptake 363 ml O 2 per minute Arterial oxygen content 200 ml O 2 per liter of blood Mixed venous oxygen content 145 ml O 2 per liter of blood Using this data together with your P ( t ) waveforms, draw the corresponding P-V loop for the LV. Assume an end-diastolic LV volume of 170 cc., and a LV “dead” volume of 15 cc for both systole and diastole. Draw linear systolic and diastolic P-V curves, and use the axes provided. See Figure. C. Correlate the following landmarks on the P-V loop with the appropriate points on the P ( t ) curves using the numeric labels below: a: begin LV contraction b: peak LV pressure c: begin LV filling d: end ejection e: begin LV ejection See Figure. D. “Ejection fraction” (EF) is defined as the percentage of the end-diastolic volume that is ejected during systole. What is the EF in this case? (Normal > 55%.) 110 EF = = 64 . 7% 170 6.022j—2004: Solutions to Quiz 1 2
E. A papillary muscle in the LV ruptures. (Assume that there are no functioning controls, and that the system has reached a new steady state.) The new arterial BP (systolic, diastolic, and mean) drops to 60% of its original value. New BP: 120 × 0 . 6 = 72 80 × 0 . 6 = 48 110 × 0 . 6 = 66 (i) Sketch two cardiac cycles showing the new P ( t ) waveforms, using the axes supplied in Figure 1.1b. Pay particular attention to the new amplitudes of the LV and LA pressures. Assume no change in the left ventricular end-diastolic pressure and volume.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}