Cardiovascular Dynamics: Simulating Compensation for Aortic Stenosis

2/23/2021 PhysioEx Exercise 5 Activity 7 PhysioEx Lab Report Exercise 5: Cardiovascular Dynamics Activity 7: Compensation in Pathological Cardiovascular Conditions Name: Date: 23 February 2021 Pre-lab Quiz Results You scored 100% by answering 4 out of 4 questions correctly. 1 Which of the following could cause an increase in peripheral resistance in the blood vessel? You correctly answered: atherosclerosis. 2 Which structures in the heart ensure that one-way flow occurs? You correctly answered: valves. 3 Which of the following might be seen in both the diseased heart and the athlete's heart? You correctly answered: thicker myocardium. 4 The type of resistance increased in aortic valve stenosis is You correctly answered: increased left-ventricular afterload. Experiment Results Predict Questions 1 Predict Question 1: You will now test three mechanisms to compensate for the decrease in flow rate caused by the decreased flow tube radius. Which mechanism do you think will have the greatest compensatory effect? Your answer: decreasing the pressure in the right (destination) beaker. 2 Predict Question 2: What do you think will happen if the pump pressure and the beaker pressure are the same? Your answer: Flow will stop. Stop & Think Questions 1 Narrowing of the right flow tube radius simulates You correctly answered: aortic valve stenosis. 1/3 2/23/2021 PhysioEx Exercise 5 Activity 7 2 What does increasing the pump pressure correspond to in the human heart? You correctly answered: increasing the force of contraction. 3 What does decreasing the right (destination) beaker correspond to in the human heart? You correctly answered: decreasing afterload. Experiment Data Condition Flow (ml/min) Rad. L Rad. R Str. V (ml) Rate Press. L (mm) (mm) (strokes/min) (mmHg) Press. Dif. R (mm Hg) Normal 5086.8 3.0 3.0 70 72.7 40 40 Aortic stenosis 3310.0 3.0 2.5 70 47.3 40 40 Increased preload 3892.9 3.5 2.5 70 55.6 40 40 Increased preload 4256.7 4.0 2.5 70 60.8 40 40 Increased preload 4479.5 4.5 2.5 70 64.0 40 40 Increased contractility 3826.3 3.0 2.5 70 54.7 40 50 Increased contractility 4270.3 3.0 2.5 70 61.0 40 60 Increased contractility 4656.3 3.0 2.5 70 66.5 40 70 Decreased afterload 3826.3 3.0 2.5 70 54.7 40 50 Decreased afterload 4270.3 3.0 2.5 70 61.0 40 60 Decreased afterload 4656.3 3.0 2.5 70 66.5 40 70 Post-lab Quiz Results You scored 100% by answering 4 out of 4 questions correctly. 1 Which of the following compensatory mechanisms was not tested? You correctly answered: decreasing the pressure in the left (source) beaker. 2 In an actual heart, what is the most logical way to compensate for a decrease in flow tube radius? You correctly answered: adjust the force of contraction of the heart. 2/3 2/23/2021 PhysioEx Exercise 5 Activity 7 3 Without a difference in pressure between the pump and the destination beaker You correctly answered: the valve will not open. 4 Athletes experience an overall __________ in peripheral resistance, so the heart generates __________ pressure to deliver the same amount of blood. An athlete's arterial pressure would likely be __________ than that in a non-athlete. You correctly answered: decrease, less, lower. Review Sheet Results 1 Explain how the heart could compensate for changes in peripheral resistance. Your answer: Increasing contractility, the force of contraction. 2 Which mechanism had the greatest compensatory effect? How well did the results compare with your prediction? Your answer: Increasing the right beaker's pressure had the greatest compensatory effect on flow, which is the opposite of my prediction. 3 Explain what happened when the pump pressure and the beaker pressure were the same. How well did the results compare with your prediction? Your answer: The flow stopped when the pump pressure and beaker pressure were the same because the pressure was equal to the beaker pressure, and enough pressure was not present for flow to occur. This was consistent with my prediction. 4 Explain whether it would be better to adjust heart rate or blood vessel diameter to achieve blood flow changes at a local level (for example, in just the digestive system). Your answer: It would be better to adjust blood vessel diameter as adjusting heart rate for an extended period can cause stress to the muscles. 3/3