REVIEW SHEET
EXERCISE 5
Cardiovascular Dynamics
Vessel Resistance
The following questions refer to Activity 1: Studying the Effect of Flow Tube Radius on Fluid Flow.
1. At which radius was the fluid flow rate the highest?
60 mm
2. What was the flow rate at this radius?
1017.4 mmHg
3. Describe the relationship between flow rate and radius size.
Direct
4. What happens to blood vessels in the body if increased blood flow is needed?
They dilate to increase flow
The following questions refer to Activity 2: Studying the Effect of Viscosity on Fluid Flow.
5. At what viscosity level was the fluid flow rate the highest?
1.0
6. Describe the relationship between flow rate and viscosity.
The greater the viscosity, the less the flow. This is an inverse relationship.
7. Was the effect of viscosity greater or less than the effect of radius on fluid flow? Why?
Viscosity has less effect than radius on fluid flow because flow is directly proportional to the fourth power of vessel radius .
8. What effect would anemia have on blood flow? Why?
It would decrease blood flow because the blood vessels constrict in anemics
The following questions refer to Activity 3: Studying the Effect of Flow Tube Length on Fluid Flow.
9. At what flow tube length was the flow rate the highest?
10mm, the blood had a shorter distance to travel
10. Describe the relationship between flow tube length and fluid flow rate.
The shorter the length the faster the flow
11. What effect do you think obesity would have on blood flow? Why?
In obese people the blood vessels lengthen, thus causing the flow of blood to decrease.
The following questions refer to Activity 4: Studying the Effect of Pressure on Fluid Flow.
12. What effect did increased pressure have on the fluid flow rate?
The greater the pressure the faster the flow
13. In the body, where does the driving pressure for fluid flow come from?
The heart
Pump Mechanics
The following questions refer to Activity 5: Studying the Effect of Radius on Pump Activity.
14. What happened to the flow rate as the right vessel radius was increased?
When the right vessel radius was increased the flow rate increases.
15. What happened to the rate (strokes/min) as the right vessel radius was increased? Why did this occur?
Stroke rate increased as the right vessel radius increased because beaker emptying time decreased.
The following questions refer to Activity 6: Studying the Effect of Stroke Volume on Pump Activity.
16. At what stroke volume tested was the pump rate the lowest?
120 mm
17. Describe the relationship between stroke volume and pump rate.
The amount of blood that the heart can pump in a given time period is known as cardiac output or CO. Cardiac output is made up of two components: Stroke volume, SV and heart rate, HR. Stroke volume is the amount of blood that the heart pumps each time it beats, and heart rate is the number of time it beats in a minute. The relationship between cardiac output, stroke volume, and heart rate can be expressed as:
CO = SV X HR.
18. Use the relationship in question 17 to explain why an athlete’s resting heart rate would be lower than that of a sedentary individual.
An athlete has a higher stroke volume than a sedentary individual, therefore the athlete needs fewer heart beats also called stroke volume to achieve the same cardiac output.
The following questions refer to Activity 7: Studying Combined Effects.
19. How did decreasing the left flow tube radius affect pump chamber filling time? Hint: Look at the change in flow rate and relate this to filling time.
Although decreasing the radius of the left flow tube increases the time required to fill the
pump, it does not affect the ability of the pump to empty.
20. When the left beaker pressure was decreased to 10 mm Hg, what happened to the filling time?
It greatly increases the time required to fill the pump. The pump's rate increases.
The following questions refer to Activity 8: Studying Compensation.
21. With the right flow tube radius decreased to 2.5 mm, what conditions did you change to bring the flow rate back to normal?
Increased the radius of the left flow tube to decrease the pump's filling time.
Decreased the pressure in the right beaker.
Increased the pump's pressure
22. A decreased tube radius is analogous to atherosclerosis (plaque formation in vessels). Describe the effect this would have on resistance in the arterial system and how the human heart might compensate for this change.
If the arteries of the body were filled with plaque deposits, the heart would need to generate ( more force to maintain blood flow, and pressure in the arterial system would be lower than normal
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