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 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 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 : a. increasing the left flow tube radius
Predict Question 2: What do you think will happen if the pump pressure and the beaker pressure are the same?
Your answer : c. Flow will stop.
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 preload
Increased contractility
Increased contractility
Decreased contractility
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
55.6
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 100% by answering 4 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.
You correctly answered: 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:
The heart can compensate for changes in peripheral resistance by increasing contractility.
2. Which mechanism had the greatest compensatory effect? How well did the results compare with your prediction?
Your answer:
Decreasing the pressure in the right-most beaker (the destination beaker) had the greatest effect because this decreases afterload. 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:
When the pump pressure and the beaker pressure were the same, the flow stopped.
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 the blood vessel diameter because at a local level, the effects will only be seen there.
Adjustments to the heart rate would have systemic effects.

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