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Cardiovascular mechanics and system integration

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4. Cardiovascular mechanics and system integration during exercise (30 points)Two patients come to the laboratory to run on a treadmill while their vital signs are beingmonitored. Patient A is an entirely normal individual with no history of cardiovascular problems.Patient B has had a heart transplant, and fully recoveredEXCEPTthat the new heart is notconnected to the nervous system. Thus, the heart of patient B will only be mechanicallycoupled to the rest of the body and will not be controlled by the brain. During exercise, thefollowing physiological changes were noted.Explain the above results for both patients in words and using the four Quadrant diagramsattached. The diagrams already contain vascular function curves (in Quadrant 1) and operatingconditions (dashed lines) for both individuals when they were at rest. As you progress throughthe questions below, adjust the function curves if necessary and add new operating lines thatare consistent with the above information during exercise.A.(4 points)Arterial pressure. Start by placing the new cardiac output values on the Qaxis. Then write down the relationship that makes up Quadrant 2 in the space below. Ifnecessary, draw a new curve that would be consistent with the changes in arterialpressure observed for both patients. Finally, add in the new operational lines. Based onyour work above, explain the arterial pressure results observed for both patients.VariablePatient APatient BCardiac outputIncreases 6-foldDoublesArterial pressureSlightly elevatedSignificantly decreasedVenous pressureSlightly elevatedSignificantly elevatedStroke volumeDoublesDoublesHeart rateIncreases 3-foldNo changeExercise toleranceNormalAbnormalEquation in Quadrant 2: Q =ΔP/p. After placing the new cardiac output values on theQ axis for both patients, it is clear that there is another change required in Quadrant 2 toobtain the observed atrial pressures. Naturally, during exercise there will be a decreasein peripheral resistance (p) for both patients, shifting the line to the right.The net effect for Patient A is that the drop in peripheral resistance would decreaseatrial pressure, but this is balanced by the large increase in cardiac output that isstimulated by the nervous system. For Patient B, cardiac output is much lower becausethere is no nervous system stimulation (only increases due to mechanical reasons, asdiscussed later), so there is an overall decrease in atrial pressure.
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