[PhysioEX Chapter 5 exercise 3] PEX-05-03

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Exercise 5: Cardiovascular Dynamics: Activity 3: Studying the Effect of Blood Vessel Length on Blood Flow Rate Lab Report

Pre-lab Quiz Results
You scored 100% by answering 4 out of 4 questions correctly.

1. When the length of the blood vessel increases, which of the following also increases?
   You correctly answered: d. both friction and surface area
2. Blood vessel length decreases
   You correctly answered: c. when we lose weight.
3. Blood flow is
   You correctly answered: b. directly proportional to vessel radius to the fourth power.
4. Which of the following correctly describes resistance to flow?
   You correctly answered: a. Resistance to flow increases with increased vessel length.

Experiment Results

Predict Question:
Predict Question: What effect do you think increasing the flow tube length will have on the fluid flow rate?
Your answer : c. The fluid flow rate will decrease.

Stop & Think Questions:
What is the relationship between fluid flow and flow tube length?
You correctly answered: b. They are inversely proportional to each other.
Which is more likely to occur on a daily basis?
You correctly answered: b. changes in blood vessel diameter

Experiment Data:
Flow (ml/min) Radius (mm) Viscosity Length (mm) Pressure (mm Hg)
90.8 3.0 3.5 10 100
60.6 3.0 3.5 15 100
45.4 3.0 3.5 20 100
36.3 3.0 3.5 25 100
30.3 3.0 3.5 30 100
26.0 3.0 3.5 35 100
22.7 3.0 3.5 40 100

Post-lab Quiz Results
You scored 100% by answering 4 out of 4 questions correctly.

1. Increasing the flow tube length is analogous to increasing blood vessel length. How did this affect the flow rate?
   You correctly answered: b. The flow rate decreased.
2. Which of the following correctly describes the relationships between blood vessel length, resistance, and blood flow?
   You correctly answered: c. Blood vessel length is directly proportional to resistance and inversely proportional to blood flow.
3. Which of the following correctly describes the relationships between blood vessel radius, resistance, and blood flow?
   You correctly answered: d. Blood vessel radius is inversely proportional to resistance and directly proportional to blood flow.
4. Which of the following describes why the body might require an increase in vessel radius?
   You correctly answered: a. to provide more blood flow and, therefore, nutrients to a particular body part

Review Sheet Results

1. Which is more likely to occur, a change in blood vessel radius or a change in blood vessel length? Explain why.
   Your answer:
   Blood vessel radius. Because of contraction or relaxation, foreign matter in blood vessel while length is fixed after growth.
2. Explain the effect that the change in blood vessel length had on flow rate. How well did the results compare with your
   prediction?
   Your answer:
   With increased length, the flow rate decreased as predicted.
3. Explain why you think blood vessel radius can have a larger effect on the body than changes in blood vessel length (use
   the blood flow equation).
   Your answer:
   While the flow rate is proportional to the length, the flow rate is proportional to the fourth power of the radius.
4. Describe the effect that obesity would have on blood flow and why.
   Your answer:
   Obesity would make vessel length longer than normal, so the flow rate of blood would decreses.