Question

1. If MAP increased from 100 to 110:
   1. how would the afferent arteriole respond?
   2. what is the purpose of this response?

2. State how the excreted amount of a substance would compare to the amount filtered if the substance is:
   1. neither reabsorbed nor secreted.
   2. reabsorbed but not secreted.
   3. secreted but not reabsorbed.

3. Explain what normally causes water to move in the reabsorption direction in the kidneys.

4. Regarding renal handling of plasma glucose:
   1. Explain what would cause the kidneys to reach the glucose transport maximum.
   2. Describe how normal urine concentration of glucose would compare to urine concentration when at transport maximum.
   3. In what part of the nephron is paracellular transport possible?
   4. Explain why paracellular transport is not the only mechanism of glucose transport.

  

5. Describe the meaning of the following terms in the context of balance and for each state if it would cause the amount of a substance in the ECF to increase or decrease:
   1. Input increase
   2. utilization
   3. production
   4. output

6. State the effect of ADH on:
   1. the amount of water reabsorbed by the kidneys
   2. the volume of water in urine
   3. the solute concentration in urine.

Answer 1

If MAP is increased from 100 to 110:

a. The afferent arteriole will undergo Arteriole Myogenic Mechanism. When blood pressure increases, smooth muscle cells in the wall of the arteriole are stretched and respond by contracting.

b. The purpose of this response is to resist the increased arterial pressure by increasing the vascular resistance, resulting in little change in blood flow.

The excreted amount of a substance would compare to the amount filtered in each case as follows:

a. neither reabsorped nor secreted : amount of substance excreted = amount of substance filtered

b. reabsorped but not secreted : amount of substance excreted amount of substance filtered

c. secreted but not reabsorped : amount of substance excreted amount of substance filtered