25. The Urinary System

In the proximal tubule, _________ ions are pumped out of the tubule via ____________ transport. This creates an ____________ gradient, causing water to be reabsorbed through _______________.

Predict what would happen if the tubule wall of the descending limb suddenly lost all its aquaporins.

Dr. Miller is a pediatric nutritionist working with a patient who has a low dietary calcium intake. Concerned about the possibility of hypocalcemia, she orders bloodwork. What hormone would you expect to be elevated in this patient’s bloodwork?

Ryan just ate a very protein-rich meal. Because of this, the amino acid levels in his blood currently exceed the transport maximum and the renal threshold for amino acids (65 mg/dL). What will happen to the excess amino acids?

In which section of the nephron is the process of reabsorption influenced by hormones?

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

d. ADH triggers water reabsorption from the nephron loop.

Explain how the peritubular capillaries are adapted for receiving reabsorbed substances.

Describe what is involved in active and passive tubular reabsorption.

Tubular reabsorption

a. Of glucose and many other substances is a T_m - limited active transport process

b. Of chloride is always linked to the passive transport of Na⁺

c. Is the movement of substances from the blood into the nephron

d. Of sodium occurs only in the proximal tubule

Which is reabsorbed by the proximal convoluted tubule cells?

a. Na⁺

b. K⁺

c. Amino acids

d. All of the above