PEX-05-07

Exercise 5: Cardiovascular Dynamics: Activity 7: Compensation in Pathological Cardiovascular Conditions Lab Report Pre-lab Quiz Results You scored 100% by answering 4 out of 4 questions correctly. 1. Which of the following could cause an increase increase in peripheral resistance in the blood vessel? You correctly answered: b. atherosclerosis 2. Which structures in the heart ensure that one-way flow occurs? You correctly answered: d. valves 3. Which of the following might be seen in both the diseased heart and the the athlete's heart? You correctly answered: c. thicker myocardium 4. The type of resistance increased in aortic valve stenosis is You correctly answered: d. increased left-ventricular afterload.

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Experiment Results Predict Question: 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 : b. increasing the pump's pressure Predict Question 2: What do you think will happen if the pump pressure and the beaker pressure are the same? Your answer : b. Flow rate will increase. Stop & Think Questions: Narrowing of the right flow tube radius simulates You correctly answered: c. aortic valve stenosis. What does increasing the pump pressure correspond to in the human heart? You correctly answered: d. increasing the force of contraction What does decreasing the right (destination) beaker correspond to in the human heart? You correctly answered: b. decreasing afterload Experiment Data: Condition Normal Aortic stenosis Increased preload Increased preload Increased contractility Increased contractility Increased contractility Decreased afterload Decreased afterload Decreased afterload Decreased afterload

Flow 5086.8 3310.0 3892.9 4256.7 4479.5 3826.3 4270.3 4656.3 3826.3 4270.3 4656.3

Rad. L 3.0 3.0 3.5 4.0 4.5 3.0 3.0 3.0 3.0 3.0 3.0

Rad. R 3.0 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5

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Str. V 70 70 70 70 70 70 70 70 70 70 70

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Rate 72.7 47.3 155.6 60.8 64.0 54.7 61.0 66.5 54.7 61.0 66.5

Press. L 40 40 40 40 40 40 40 40 40 40 40

Press. Dif. R 40 40 40 40 40 50 60 70 80 60 70

Post-lab Quiz Results You scored 75% by answering 3 out of 4 questions correctly. 1. Which of the following compensatory mechanisms was not  tested? You correctly answered: c. 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: b. adjust the force of contraction of the heart 3. Without a difference in pressure between the pump and the destination beaker You correctly answered: a. 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. Your answer: c. decrease, more, higher Correct answer: d. decrease, less, lower

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Review Sheet Results 1. Explain how the heart could compensate for changes in peripheral resistance. Your answer: ....... 2. Which mechanism had the greatest compensatory effect? How well did the results compare with your prediction? Your answer: ...... 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: ...... 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: .......

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