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Serendipityou Serendipityou
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12 years ago
PhysioEx 9.0 Review Sheet Exercise 5 Questions


I noticed that several people asked for these questions and answers, so I compiled a list of all the questions along with all the answers I had available to me.  Please feel free to add the answers that you know, as well as make corrections to the ones that I had on hand.  I will try to post more answers later.



Activity 1:
1:  Explain how the body established a pressure gradient for fluid flow.
Answer:  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?
Answer:  Increasing the flow tube radius resulted in an increase in the flow rate.  It corresponded with my prediction.

3:  Describe the effect that radius changes have on the laminar flow of a fluid.
Answer:

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?
Answer:



Activity 2:
1 (5):  Describe the components in the blood that affect viscosity.
Answer:

2 (6):  Explain the effect that viscosity had on flow rate.  How well did the results compare with your prediction?
Answer:  The higher the viscosity the lower the flow = an inverse relationship.

3 (7):  Describe the graph of flow versus viscosity.
Answer:  Viscosity has a lower effect than radius on fluid flow because flow is directly proportional to the radius to the fourth power

4 (8):  Discuss the effect that polyethemia would have on viscosity and blood flow.
Answer:



Activity 3:
1 (9):  Which is more likely to occur, a change in blood vessel radius or a change in blood vessel length?  Explain why.
Answer:

2 (10):  Explain the effect that the change in blood vessel length had on flow length.  How well did the results compare with your prediction?
Answer:

3 (11):  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).
Answer:

4 (12):  Describe the effect that obesity would have on blood flow and why.
Answer:



Activity 4:
1 (13):  Explain the effect that pressure changes had on flow rate.  How well did the results compare with your prediction?
Answer:

2 (14):  How does the plot differ from the plots for tube radius, viscosity, and tube length?  How well did the results compare with your prediction?
Answer:

3 (15):  Explain why pressure changes are not the best way to control blood flow.
Answer:

4(16):  Use your data to calculate the increase in flow rate in ml/min/mm Hg.
Answer:



Activity 5:
1 (17):  Explain the effect of increasing the right flow tube radius on the flow rate, resistance, and pump rate.
Answer:

2 (18):  Describe what left and right beakers in the experiment correspond to in the human heart.
Answer:

3 (19):  Briefly describe how the human heart could compensate for flow rate changes to maintain blood pressure.
Answer:



Activity 6:
1 (20):  Describe the Frank-Starling law in the heart.
Answer:

2 (21):  Explain what happened to the pump rate when you increased the stroke volume.  Why do you think this occurred?  How well did the results compare with your prediction?
Answer:

3 (22):  Describe how the heart alters stroke volume.
Answer:

4 (23):  Describe the intrinsic factors that control stroke volume
Answer:



Activity 7:
1 (24):  Explain how the heart could compensate for changes in peripheral resistance.
Answer:

2 (25):  Which mechanism has the greatest compensatory effect?  How well did the results compare with your prediction?
Answer:

3 (26):  Explain what happened when the pump pressure and the beaker pressure were the same.  How well did the results compare with your prediction?
Answer:

4 (27):  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).
Answer:
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wrote...
12 years ago
Activity 3 ( 11) .eripheral resistance is opposition to flow and is a measure of the amount of friction the blood encounters as it passes through the vessels. Most friction is encountered in the peripheral circulation.
 
There are three important sources of resistance:
1. blood viscosity
2. vessel length
3. vessel diameter
 
Blood viscosity is the internal resistance to flow and is related to the thickness or stickiness of a fluid. The greater the viscosity, the less easily molecules slide past one another. The longer the vessel, the greater the resistance. Since viscosity and vessel length are normally unchanging, these factors can be considered constant.
 
Blood vessel diameter changes often and is a very important factor in altering peripheral resistance. Fluid close to the walls of a tube or channel is slowed by friction as it passes along the wall, whereas fluid in the center of the channel flows more freely and faster. The smaller the tube, the greater the friction because relatively more fluid contacts the tube walls. Because arterioles are small diameter vessels and can enlarge or constrict in response to neural and chemical controls, they are the major determinants of peripheral resistance.
19Sam94,  duddy,  coolguy87
wrote...
12 years ago
Activity 2
1(5)
The viscosity of blood is due to the presence of plasma proteins, white blood cells, red blood cells, and platelets. These elements and plasma proteins create resistance as they slide past one another, increasing resistance to flow.
19Sam94,  coolguy87
wrote...
11 years ago
Activity 1

3 - The larger the radius, the greater the laminar flow and vice versa. Since the vessel is larger, there's more room for the blood to move through, thus increasing laminar flow.

4 - An increase in the size of the radius results in an increased flow rate.
19Sam94,  coolguy87
wrote...
11 years ago
Activity 2

4 - 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.
19Sam94,  dogwood,  coolguy87
wrote...
11 years ago
Activity 3

1 - A change in blood vessel radius is more likely to occur on a daily basis in order to maintain homeostasis.

2 - The fluid flow rate decreased as the flow tube length increased. An increase in blood vessel length would result in a decrease in fluid flow rate due to their inverse relationship.

4 - Obesity would result in decreased blood flow because vessels must increase in length in order to serve the increased amount of adipose tissue in the body.
19Sam94,  charmed9,  dogwood,  DoofLovr,  coolguy87
wrote...
11 years ago
Activity 4

1 - The increase in pressure resulted in a corresponding increase in flow rate. A decrease in pressure would result in a decrease in flow rate.

2 - The plot was linear. The other plots were curved.

3 - 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 not be a reasonable method of flow control because a large change in pressure is needed to significantly change flow rate.

4 - 1.4 ml/min/mm Hg
doseofmegan,  dogwood,  coolguy87,  gamze
wrote...
11 years ago
Activity 5

1 - As the right flow tube radius is increased, blood flow increases, resistance decreases, and the pump rate increases.

2 - The left beaker simulates blood coming from the lungs. The right beaker simulates blood traveling to the systemic circuit.

3 - If the flow rate increases, the heart must pump faster to maintain blood pressure.
bloo142,  dogwood,  kwall41890,  coolguy87
wrote...
11 years ago
Activity 6:

1 - The Frank-Starling Law of the Heart is the intrinsic relationship between the amount of ventricular stretching (amount of venous return) and the contractile force. This means that with an increase in the end-diastolic volume (caused by an increase in ventricular filling), the more the heart is stretched. This increase in the stretch of the heart causes a longer initial cardiac length before the hearts contraction. A greater force on the following heart contraction is due to the increase in cardiac length; furthermore, this causes an increase in the stroke volume. In other words this law states “more in = more out.”

2 - As the stroke volume is increased, it takes longer to fill the pump and the pump rate slows. To maintain adequate blood flow to tissues, the stroke volume must be greater if the heart rate is lowered. If the rate remains constant, increasing the stroke volume causes cardiac output to increase.

3 - By altering contractility, the force of contraction will increase stroke volume.

4 - The intrinsic factors that determine stroke volume are preload and contractibility.  The preload gives the volume of blood that the ventricle has available to pump, as well as the end diastolic length of the muscle.  The contractility is the force that the muscle can create at the given length. These factors establish the volume of blood pumped with each heartbeat.
19Sam94,  dogwood,  coolguy87,  bio_man
wrote...
11 years ago
Activity 7:

1 - The heart can compensate for changes in peripheral resistance by increasing contractility.

2 - Decreasing the pressure in the right-most beaker (the destination beaker) had the greatest effect because this decreases afterload.

3 - When the pump pressure and the beaker pressure were the same, the flow stopped.

4 - 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.

19Sam94,  dogwood,  coolguy87,  ktesta,  bio_man
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