Carbonic anhydrase is a very important enzyme that is utilized by the body. The enzyme catalyzes the following reaction:

A class of drugs that inhibits this enzyme is carbonic anhydrase inhibitors (eg. acetazolamide, brinzolamide, dorzolamide). These drugs are commonly prescribed in patients with glaucoma, hypertension, heart failure, high altitude sickness and for the treatment of basic drugs overdose.

In patients with hypertension, carbonic anhydrase inhibitors will prevent the reabsorption of sodium chloride in the proximal tubule of the kidney. When sodium is reabsorbed back into the blood, the molecule creates an electrical force. This electrical force then pulls water along with it into the blood. As more water enters the blood, the blood volume increase. By preventing the reabsorption of sodium, water reabsorption is reduced and the blood pressure decreases.

When mountain climbing, the atmospheric pressure is lowered as the altitude increases. As a result of less oxygen into the lungs, ventilation increases. From the equation above, hyperventilation will result in more being expired. Based on Le Chatelier’s principle, the reaction will shift to the left. Since there is more bicarbonate than protons in the body, the blood will become more basic (respiratory alkalosis). To prevent such life threatening result, one would take a carbonic anhydrase inhibitor to prevent the reaction from shifting to the left.

Carbonic anhydrase inhibitors are useful in patients with a drug overdose that is acidic. The lumen of the collecting tubule is nonpolar. Due to the lumen's characteristic, molecules that are also nonpolar and uncharged are able to cross the membrane and re-enter the circulatory system. Since carbonic anhydrase inhibitors alkalize the urine, acidic molecules stay in a charged state.

Which of the following side effects is/are expected in a drug that overstimulates carbonic anhydrase?

I. Increased in the blood's pH

II. Increased in the urine's pH

III. Increased bicarbonate level in the blood

Which of the following would most likely NOT happen in the excretory system if a person has not drunk water for an extended period of time?

The effect of the hormone vasopressin (ADH) on the kidney is best described by which of the following?

Which of the following conditions would you not predict in a severely dehydrated patient?

Which of the following is the function of aldosterone?

Aldosterone is a key hormone used by the kidneys during urine formation.

What is the function of aldosterone in the kidneys?

The juxtaglomerular cells of the nephron regulate __________.

What substance is produced by the juxtaglomerular apparatus in the kidney to help regulate blood volume and pressure?

What is the role of antidiuretic hormone (ADH)?

The interaction between blood pressure and kidney function in humans requires coordination by the renin-angiotensin-aldosterone system (RAAS). This system involves the dynamic interplay of the kidneys, lungs, and blood vessels to carefully regulate sodium and water balance.

A normal human kidney has cells adjacent to the glomerulus called juxtaglomerular cells. These cells sense sodium content in urine of the distal convoluted tubule, releasing renin in response to a low level. Renin is an enzyme that converts angiotensinogen to angiotensin I (AI). AI is converted to angiotensin II (AII) by angiotensin converting enzyme (ACE) in the lung.

AII stimulates aldosterone secretion in the zona glomerulosa of the adrenal gland. Aldosterone then acts to upregulate the sodium-potassium pump on the basolateral side of distal tubule epithelial cells to increase sodium reabsorption from the urine, as well as increasing potassium excretion.

A doctor is examining a patient in a dialysis center. She notices that the patient's blood pressure is high. A common treatment of high blood pressure is a class of drugs called ACE inhibitors. After administering an ACE inhibitor, which of the following is likely to be true?