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ACTIVITY 1: The Effect of Arteriole Radius on Glomerular Filtration
Answers
According to your lab manual, in humans the glomerular filtration rate (GFR) ranges from _____ to _____ ml/minute.
80;140*****
When the radii of both the afferent arteriole and efferent arteriole were set at 0.45mm, the GFR was approximately ______ ml/minute.
40
60
80
120
C******
True or False: Drinking a lot of caffeine (coffee or cola) leads to an increased urine volume. This might result from a decrease in the radius of the efferent arteriole.
True*******
What are two primary functions of the kidney?
excretion and regulation*****
What are the components of the renal corpuscle?
it consists of the glomerulus enclosed in the glomerulus capsule(Bowman's capsule).*****
Starting at the renal corpuscle, list the components of the renal tubule as they are encountered by filtrate.
The filtrate flows from the Bowman's capsule into the renal tubule called the proximal convoluted tubule then into the loop of Henle.******
Describe the effect of decreasing the afferent arteriole radius on glomerular capillary pressure and filtration rate.
The glomerular capillary pressure will decrease and the filtration rate will decrease.******
Describe the effect of increasing the afferent arteriole radius on glomerular capillary pressure and filtration rate.
The glomerular capillary pressure will increase and the filtration rate will increase.******
Describe the effect of decreasing the efferent arteriole radius on glomerular capillary pressure and filtration rate.
The glomerular capillary pressure will increase and the filtration rate will increase.*****
Describe the effect of increasing the efferent arteriole radius on glomerular capillary pressure and filtration rate.
They both will decrease.****
ACTIVITY 2: The Effect of Pressure on Glomerular Filtration
True or False: In humans, glomerular capillaries can filter as much as 180 liters of filtrate in 24 hours.
True****
In this simulation, when the radius of the afferent arteriole was 50mm, the radius of the efferent arteriole was 0.45mm, and the beaker pressure was set to 100mmHg, the GFR was approximately _____ ml/min.
158.20****
When the valve between the collecting duct and the urinary bladder was closed and when the beaker pressure was 100mmHg, the GFR was approximately _____ ml/min and the urine volume was approximately ______ ml.
100; 100
110; 50
60; 0
110; 0
D*****
As the systemic blood pressure increased, what happened to the glomerular capillary pressure and the GFR?
They both increased.*****
Compare the urine volume in your baseline data with the urine volume as you increased the systemic blood pressure.
The urinary volume increased. The baseline was 161.76 at 70, 200.44 at 90, and 209.72 at 100.*****
How could the change in urine volume with the increase in blood pressure be viewed as being beneficial to the body?
It is getting out any unneeded substances in the body or cleaning out the body quicker. *****
When the one-way valve between the collecting duct and the urinary bladder was closed, what happened to the filtrate pressure in Bowman’s capsule (was not directly measured) and the GFR?
The pressure stayed the same(when it was 70 beaker pressure/the valve was open) and the GFR decreased.****
How did increasing the systemic blood pressure alter the results when the valve was closed?
The pressure stayed the same(when it was 100 beaker pressure/the valve was open) and the GFR was less than it was when it was open. The amounts were higher than when it was at 70 beaker pressure. *****
ACTIVITY 3: Renal Response to Altered Blood Pressure
True or False: The renal system (the kidneys) is very important in regulating plasma osmolarity, plasma volume, and the body’s electrolyte balance.
True****
In this simulation, when the radius of the afferent arteriole was 0.60mm, the radius of the efferent arteriole was 0.45mm, and the beaker pressure was 70mmHg, the GFR was approximately _______ mm/min.
114.72****
When the radius of the afferent arteriole was 0.60mm, the radius of the efferent arteriole was 0.35mm, and the beaker pressure was 70mmHg, the urine volume changed to approximately ______ ml.
50
80
200
240
D*****
List the several “mechanisms” you have explored that change the GFR. How does each of them specifically alter the GFR?
Both increasing the afferent arteriole radius and decreasing the efferent arteriole resulted in an increase in glomerular filtration rate.*****
Describe and explain what happened to the glomerular capillary pressure and GFR when both arteriole radii changes were implemented simultaneously with the low blood pressure condition.
When both arteriole radii changes were implemented, glomerular filtration rate and pressure rose above baseline values.*****
Which arteriole radius adjustment was more effective at compensating for the effect of low blood pressure on the GFR?
Increasing the afferent radius had a greater effect than decreasing the efferent radius because there was a greater increase in glomerular pressure.****
ACTIVITY 4: Solute Gradients and Their Impact on Urine Concentration
Antidiuretic hormone (ADH)
is synthesized in the hypothalamus and secreted from the posterior pituitary gland.
affects the reabsorption of water in the kidneys.
if absent from the body, results in a condition named diabetes insipidus.
All of the above are correct.
D*****
If a person is very dehydrated, compared to normal, the urine volume will ______ and the concentration of the urine will ________.
increase; increase
increase; decrease
decrease; increase
decrease; decrease
C*****
True or False: ADH affects water reabsorption by its effect on the glomerular arterioles.
True****
What happened to the urine concentration as the solute concentration in the interstitital space was increased?
It increased****
What happened to the volume of urine as the solute concentration in the interstitial space was increased?
It decreased****
What do you think would happen to the urine volume if you did not add ADH to the collecting duct?
The urine volume will significantly increase because there is no enhancement of water permeability in the collecting duct and the distal tubule and less water will be reabsorbed. the less water reabsorbed, the more urine will be formed.*****
Is most of the tubule filtrate reabsorbed into the blood stream (the body) or excreted in urine? Explain.
Most of the tubular filtrate is reabsorbed to prevent fluid loss and maintain homeostasis.****
ACTIVITY 5: Reabsorption of Glucose via Carrier Proteins
True or False: Renal processing of glucose that is filtered in the glomeruli is primarily by secretion back into the blood stream.
True****
In this simulation, you varied the number of glucose carriers. When the glucose concentration in the tubules and urinary bladder became zero, the total number of glucose carriers was ______.
400****
True or False: The kidneys of a person with type 1 diabetes are able to synthesize extra glucose carrier molecules so that no glucose is excreted in urine.
False****
When there were 200 glucose carriers, the glucose concentration in the distal tubule and urinary bladder was approximately
0
2.5
5
10
B****
What happens to the concentration of glucose in the urinary bladder as the number of glucose carriers increases?
It decreases.****
What types of transport are utilized during glucose reabsorption and where do they occur?
Glucose is first reabsorbed by secondary active transport at the apical membrane of PCT cells and then via facilitated diffusion along the basolateral membrane.****
Why does the concentration of glucose in the urinary bladder become zero in these experiments?
Glucose in the urine become zero when glucose carriers were added which means adding enough glucose carriers will facilitate re-uptake of the glucose leaving nothing in the unabsorbed water formed as urine.*****
A person with type 1 diabetes cannot make insulin in the pancreas; a person with type 2 diabetes does not respond normally to the insulin that is made in the pancreas. In either case, why (or when) would you expect to find glucose in the person’s urine?
Urine of the diabetic will have high glucose concentration. Due to lack of the glucose carriers relatively less than the amount of glucose to be transported, high amount of glucose could not be carried across leaving high concentration discarded with the urine formed.*****
ACTIVITY 6: The Effect of Hormones on Urine Formation
The hormone aldosterone promotes renal absorption of _______ into the body and the secretion of _______ from the body.
Water; NaCl
sodium; potassium
NaCl; potassium
Glucose; NaCl
C****
In this simulation, when both aldosterone and ADH were added, the concentration of potassium in the urine increased from approximately 6 to ______.
65****
How did the addition of aldosterone affect urine volume (compared with baseline)?
It decreased, it was 201 at baseline and with aldosterone it was 180.9.****
How did the addition of ADH affect urine volume (when compared with baseline)?
Why did the addition of ADH also affect the concentration of potassium in the urine (when compared with baseline)?
It decreased drastically from 201 at baseline to 16.88 with ADH. *****
There was more potassium secretion into the distal tubule and more water absorption in the collecting duct.*****
What is the principal determinant for the release of aldosterone from the adrenal cortex?
Decreased blood pressure and the need to reabsorb sodium.****
How did the addition of both aldosterone and ADH affect urine volume (compared with baseline)?
It decreased drastically from 201 at baseline to 12.67 with both aldosterone and ADH.****
What is the principal determinant for the release of ADH from the posterior pituitary gland?
Does ADH favor the formation of dilute urine or of concentrated urine?
Decreased blood pressure and the need to reabsorb water into the blood to increase blood pressure. Concentrated urine.****
Which hormone (aldosterone or ADH) has the greater effect on urine volume?
ADH*****
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