# Physio Ex Lab Exercise 5 Cardiovascular Dynamics 1-4 Essay

Name: Brenna Wiley Date: 17 June 2012 Title of Lab: Lab Report 2 Physio Ex Lab Exercise 5 Cardiovascular Dynamics Learning Objectives: Activities 1-4 * To understand how blood vessel radius affects blood flow rate. * To understand how vessel radius is changed in the body. * To understand how to interpret a graph of blood Bessel radius versus blood flow rate. * To understand how blood viscosity affects blood flow rate. * To list the components in the blood that contribute to blood viscosity. * To explain conditions that might lead to viscosity changes in the blood.

* To understand how to interpret a graph of viscosity versus blood flow. * To understand how blood vessel length affects blood flow rate. * To explain conditions that can lead to blood vessel length changes in the body. * To compare the effect of blood vessel length changes with the effect of blood vessel radius changes on blood flow rate. * To understand how blood pressure affects blood flow rate. * To understand what structure produces blood pressure in the human body. * To compare the plot generated for pressure versus blood flow to those generated for radius, viscosity, and length.

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Data: * Activity 1 Effect of Blood Vessel Radius on Blood Flow Rate Flow (ml/min)| Radius (mm)| Viscosity| Length (mm)| Pressure (mm Hg)| 4. 0| 1. 5| 1. 0| 50| 100| 12. 6| 2. 0| 1. 0| 50| 100| 30. 7| 2. 5| 1. 0| 50| 100| 63. 6| 3. 0| 1. 0| 50| 100| 117. 8| 3. 5| 1. 0| 50| 100| 201. 0| 4. 0| 1. 0| 50| 100| 321. 9| 4. 5| 1. 0| 50| 100| 490. 6| 5. 0| 1. 0| 50| 100| * Activity Questions 1. Describe the relationship between vessel radius and blood flow rate? Vessel radius has a direct relationship with blood flow. As blood vessels constrict (vasoconstriction), blood flow is decreased.

As blood vessels dilate (vasodilatation), blood flow is increased. 2. In this activity you altered the radius of the flow tube by clicking + and – buttons. Explain how and why the radius of blood vessels is altered in the human body. Contraction or relaxation of smooth muscle of the blood vessel results in a decrease or increase in the blood vessel radius. Different organs have different requirements for blood. 3. Describe the appearance of your plot of blood vessel radius versus blood flow rate and relate the plot to the relationship between these two variables.

The points on the plot start at 0 (radius) and increase to 500 (flow) as the radius increases. 4. Describe an advantage of slower blood velocity in some areas of the body, for example, in the capillaries of our fingers. Allows for more time for gas exchange * Review Sheet Results 1. Explain how the body establishes a pressure gradient for fluid flow. The body establishes a pressure gradient for fluid flow due to the pressure difference between the two ends of the vessel. 2. Explain the effect that the flow tube radius change had on flow rate. How well did the results compare with your prediction?

The flow tube radius change allowed for faster flow. I predicted the flow would be faster. 3. Describe the effect that radius changes have on the laminar flow of a fluid. In a fully constricted vessel, proportionately more blood in contact with the vessel wall and there is less laminar flow, significantly impeding the rate of blood flow in the fully constricted vessel relative to that in the fully dilated vessel. 4. Why do you think the plot was not linear? (Hint: look at the relationship of the variables in the equation). How well did the results compare with your prediction?

The plot was not linear because the radius was increasing allowing the blood to flow faster. I predicted that it wouldn’t be linear. * Activity 2 Effect of Blood Viscosity on Blood Flow Rate Flow (ml/min)| Radius (mm)| Viscosity| Length (mm)| Pressure (mm Hg)| 490. 6| 5. 0| 1. 0| 50| 100| 245. 3| 5. 0| 2. 0| 50| 100| 163. 5| 5. 0| 3. 0| 50| 100| 122. 7| 5. 0| 4. 0| 50| 100| 98. 1| 5. 0| 5. 0| 50| 100| 81. 8| 5. 0| 6. 0| 50| 100| 70. 1| 5. 0| 7. 0| 50| 100| 61. 3| 5. 0| 8. 0| 50| 100| * Activity Questions 1. Describe the effect on blood flow rate when blood viscosity was increased.

As the viscosity increased, the blood flow decreased 2. Explain why the relationship between viscosity and blood flow rate is inversely proportional. Viscosity and blood flow are inversely proportional to each other. When viscosity increases, the blood is thicker and there is a greater resistance to flow. This results in a decrease in the flow rate. 3. What might happen to blood flow if you increased number of blood cells? Increasing the number of blood cells would increase the viscosity. This would result in a decrease in the flow rate due to the increased viscosity.

* Review Sheet Results 1. Describe the components in the blood that affect viscosity. The Hemacratic 2. Explain the effect that the viscosity change had on flow rate. When viscosity increases, the blood is thicker and there is a greater resistance to flow. This results in a decrease in the flow rate. 3. Describe the graph of flow versus viscosity. As viscosity increases, the blood flow decreases. 4. Discuss the effect that polycythemia would have on viscosity and on blood flow. Polycythemia is an increase in the red blood cell numbers.

This would result in an increase in viscosity and a corresponding decrease in blood flow. * Activity 3 Effect of Blood Vessel Length on Blood Flow Rate 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| * Activity Questions 1. Is the relationship between blood vessel length and blood flow rate directly proportional or inversely proportional? Why?

They are directly proportional peripheral resistance. 2. Which of the following can vary in size more quickly: blood vessel diameter or blood Bessel length? Blood Vessel Diameter 3. Describe what happens to resistance when blood vessel length increases. Because of the friction between the blood and vessel walls, the resistance increases. * 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. A change in the radius of blood vessels is more likely to occur over a change in vessel length.

The change in blood vessel length only really occurs during growth phases in the human body. When a child is growing to adulthood, its vessel length is increased to accommodate the body length and when a person gains weight the vessels must elongate to accommodate for the added area of the needed nutrition. Whereas, a decrease in body weight causes a decrease in the length of blood vessels due to the decrease of area needing nutrition in the body. 2. Explain the effect that the change in blood vessel length had on flow rate. How well did the results compare with your prediction?

The flow slowed because of the friction with the vessel walls. I predicted the blood would flow slower. 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). The blood vessel radius varies to a power of four which is why the changes are greater than blood vessel length changes. 4. Describe the effect that obesity would have on blood flow and why. You’d have increased body mass and adds resistance to circulation which decreases blood flow to extremities and major organs.

Your heart would try to compensate for this by increasing it’s rate, causing high blood pressure. * Activity 4 Effect of Blood Pressure on Blood Flow Rate Flow (ml/min)| Radius (mm)| Viscosity| Length (mm)| Pressure (mm Hg)| 35. 0| 5. 0| 3. 5| 50| 25| 70. 1| 5. 0| 3. 5| 50| 50| 105. 1| 5. 0| 3. 5| 50| 75| 140. 2| 5. 0| 3. 5| 50| 100| 175. 2| 5. 0| 3. 5| 50| 125| 210. 3| 5. 0| 3. 5| 50| 150| 245. 3| 5. 0| 3. 5| 50| 175| 280. 4| 5. 0| 3. 5| 50| 200| * Activity Questions 1. How does increasing the driving pressure affect the blood flow rate? It increases the blood flow rate 2.

Is the relationship between blood pressure and blood flow rate directly proportional or inversely proportional? Why? Blood flow is directly proportional to blood pressure because the pressure difference between the ends of a vessel is the driving force for blood flow. 3. How does the cardiovascular system increase pressure? The heart provides the initial pressure and the vascular resistance contributes to the pressure gradient. 4. Although changing blood pressure can be used to alter the blood flow rate, this approach causes problems if it continues indefinitely. Explain why.

It causes added pressure to the heart, which could end up causing a heart attack with continued high blood pressure. * Review Sheet Results 1. Explain the effect that pressure changes had on flow rate. How well did the results compare with your prediction? The pressure made the blood flow faster. I predicted correctly. 2. How does the plot differ from the plots for tube radius, viscosity, and tube length? How well did the results compare with your prediction? 3. Explain why pressure changes are not the best way to control blood flow. Increasing the pressure increases fluid flow.

The length versus flow rate plot is linear, whereas the plots for radius, viscosity, and length are all exponential. Changing pressure would now be a reasonable method of flow control because a large change in pressure is needed to significantly change flow rate. 4. Use your data to calculate the increase in flow rate in ml/min/mm Hg. Discussion: What did you learn by doing this lab and how can you relate the information to daily life? This lab taught me the way the blood vessels work to get blood where it needs to go and the importance of blood pressure.

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