21. Bicarbonate is reabsorbed into the epithelial cells of theproximal convoluted tubule as ________________.

1. HCO3-
2. CO2
3. H2CO3
4. Carbonic anhydrase

22. Loop diuretics block the Na+/ 2Cl-/K+ cotransporter on theascending loop of henle. How does this reduce waterreabsorption?

1. By preventing the reabsorption of sodium ions, water is notreabsorbed from the ascending loop of henle
2. It causes hyperkalcemia which stimulates Aldosterone secretion,thereby, indirectly causing the excretion of sodium, potassium andwater.
3. It abolishes and/or reduces the osmotic gradient between thedescending loop of henle and the ascending vasa recta
4. It increases the sodium ion concentration in the loop of Henlewhich stimulates the release of ADH causing an increase in waterexcretion.

23.During World War II when there wasa shortage of penicillin, an anti-gout medication, Probenecid wasadministered with penicillin. Why?

1. Probenecin blocks the filtration and secretion ofPenicillin
2. Probenecid blocks the filtration of Penicillin
3. Although penecillin is filtered, Probenecid blocks the organicanion transporter on the basoalateral membrane of the proximaltubule preventing secretion and urine loss of penecillin
4. Probenecin blocks organic cation transporters on the apicalmembrane of the proximal tubule, preventing the secretion ofpenicillin

24.What type of compensation would youexpect in a patient with metabolic alkalosis?

A. A compensatory respiratory acidosiscaused by a decrease in respiratory rate

B. A compensatory metabolic acidosiscaused by an increase loss of bicarbonate in the urine

C. A compensatory respiratoryalkalosis caused by an increased in respiratory rate

D. A compensatory alkalosis caused byan increased loss of H+ in the urine