2. (2 pts) The heart ventricles are compliant vessels, but they have one very im

Question

2. (2 pts) The heart ventricles are compliant vessels, but they have one very important difference from ordinary blood vessels: their compliance changes dramatically during each heart cycle from a relatively large value during filling (diastole) to a small value during ejection (systole). a. The end-diastolic volume of blood, VED, at the very end of diastole in the left ventricle is about 135 mL at a filling pressure of 8.0 mmHg. What is its end-diastolic compliance? (Assume the residual volume of the left ventricle is negligible, i.e., zero). [ans: C 0.017 L/mmHg ] b. At the peak of systole-which occurs about 175 ms after the end of diastole-the left ventricle compliance has a value of 0.000800 L/mmHg. The outflow of blood into the aorta averages 200 mL/s during systole. What is the systolic pressure in the ventricle at this moment? [ans: P 125 mmHg ]

Explanation / Answer

ans 2..a..end diastolic compliance = end diastolic volume in llitre ddivided by filling pressure in mm of Hg

EDC=0.135/8

=0.0168

rounding off

ans is 0.017 l/mm Hg

ans b...using the same formula we used above

pressure=volume/compliance

=0.2/0.0016(read below why is it taken 0.0016 and not 0.0008)

=125

now u know very well that pressure from the contraction of left ventricle is transmitted to aorta and bicuspid valve both which are closed at that time..so to the systolic pressure in ventricle we have to double the value

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