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Example Questions
Example Question #31 : Kidney And Nephron Physiology
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 
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 
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 statement(s) will contradict carbonic anhydrase inhibitors' usefulness in patients with hypertension?
The reabsorption of 
All of these
Water is only reabsorbed in the collecting tubule of the kidneys
None of these
The reabsorption of 
Water is only reabsorbed in the collecting tubule of the kidneys
In patients with hypertension, the blood volume is too high resulting in high blood pressure. carbonic anhydrase inhibitors will prevent water absorption by preventing sodium chloride reabsorption. As described from the passage, without sodium reabsorption at the proximal tubule, there will be no electrochemical drive for the reabsorption of water. carbonic anhydrase inhibitors mainly work on the proximal tubule where the majority of water reabsorption occurs.
Example Question #482 : Biology
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 
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
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.
Based on the passage, which of the following statements, if true, would contradict the effectiveness of carbonic anhydrase inhibitors as a treatment?
The distal tubule of the kidney is impermeable to water
The proximal tubule of the kidney is impermeable to water
None of these
When sodium chloride is absorbed, the electric force created will pull magnesium with greater force than water
Even in a basic environment, sometimes an acidic molecule is able to retain it's proton
The proximal tubule of the kidney is impermeable to water
The proximal tubule has a high permeability for water. In patients with hypertension and/or heart failure, blocking the reabsorption of water at the proximal tubule will lower the blood's volume and blood's pressure. Therefore, if the proximal tubule is impermeable to water, then regulating the site with a carbonic anhydrase inhibitor has no purpose.
Example Question #485 : Biology
Aldosterone is a key hormone used by the kidneys during urine formation.
What is the function of aldosterone in the kidneys?
Aldosterone increases the amount of urine production
Aldosterone helps to decrease blood pressure
Aldosterone increases the reabsorption of sodium from nephron filtrate
Aldosterone decreases the reabsorption of sodium from nephron filtrate
Aldosterone increases the reabsorption of sodium from nephron filtrate
Aldosterone increases the reabsorption of sodium from nephron filtrate.
The reabsorption of sodium leads to reabsorption of water, which makes the urine more concentrated. Increasing aldosterone production would lead to increased blood pressure, since more water is retained in the blood stream.
Example Question #1 : Excretory Regulation Mechanisms
What is the role of antidiuretic hormone (ADH)?
ADH decreases the reabsorption of water from the collecting duct
ADH increases the reabsorption of water from the collecting duct
ADH increases the reabsorption of water from the loop of Henle
ADH decreases the reabsorption of water from the loop of Henle
ADH increases the reabsorption of water from the collecting duct
Antidiuretic hormone, also known as vasopressin, increases the reabsorption of water from the collecting duct. It increases the permeability of the collecting duct, which allows water to be reabsorped and makes the urine more concentrated.
You can remember what antidiuretic hormone does by remembering that diuetics increase urine production; therefore an ANTIdiuretic will decrease urine production.
Example Question #2 : Excretory Regulation Mechanisms
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?
Increase in antidiuretic hormone secretion
Increase in blood volume
Increase in aldosterone secretion
Decrease in urine volume
Decrease in sodium
Increase in blood volume
The signal to increase water reabsorption in the nephrons comes from antidiuretic hormones and aldosterone. The urine volume also decrease in an attempt to retain the fluids already present in the body. Since the body is trying to conserve the fluids it has and there are no incoming fluids, the blood volume should not increase.
Example Question #41 : Excretory And Digestive Systems
The juxtaglomerular cells of the nephron regulate __________.
blood osmolarity
blood pressure
blood pH
urine acidity
blood osmolarity
Juxtaglomerular cells respond to low levels of sodium and secrete renin in response, which results in the release of aldosterone from the adrenal cortex. Aldosterone, as a result, will increase sodium reabsorption from the collecting duct. This will in turn increase blood pressure, however, the direct role of the cells themselves is to regulate blood osmolarity.
Example Question #1 : Excretory Regulation Mechanisms
The effect of the hormone vasopressin (ADH) on the kidney is best described by which of the following?
It increases sodium reabsorption in the distal convoluted tubule
It decreases the glomerular filtration rate
It increases the permeability of the collecting duct to water
It increases water reabsorption in the afferent convoluted tubule
It increases the permeability of the collecting duct to water
Vasopressin acts on the collecting duct in order to increase its permeability to water. This results in more water being reabsorbed, and increases blood pressure.
Example Question #2 : Excretory Regulation Mechanisms
Which of the following conditions would you not predict in a severely dehydrated patient?
Antidiuretic hormone (ADH) would be elevated
Aldosterone would be elevated
The collecting ducts would be permeable to water
Renin would be secreted at low levels
Renin would be secreted at low levels
In a severely dehydrated patient, the kidneys will be acting to preserve water in the body. Renin is secreted by the kidneys, and is the starting enzyme for a cascade that stimulates the release of aldosterone. Aldosterone raises the blood pressure of the body by acting on the distal tubule, and antidiuretic hormone (ADH) is responsible for making the collecting ducts permeable to water, thus concentrating the urine. Because of this, we would expect that renin levels would be higher than normal in a dehydrated patient.
Example Question #41 : Excretory System
Which of the following is the function of aldosterone?
Sodium and water retention
Sodium excretion
Sodium retention
Water retention
Sodium and water excretion
Sodium and water retention
Aldosterone is released from the adrenal cortex and acts on nephrons to increase water and sodium retention. Aldosterone directly affects the synthesis of sodium ion channels and sodium-potassium pump proteins in the nephron, actively leading to sodium retention and indirectly leading to water retention based on increased blood osmolarity. Antidiuretic hormone (ADH), on the other hand, works by just retaining water without directly affecting sodium retention.
Example Question #3 : Excretory Regulation Mechanisms
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?
Renin levels will immediately decrease
Renin levels will remain elevated
Angiotensin I levels will immediately decrease
Sodium reabsorption in the distal tubule will increase
Aldosterone levels will remain high
Renin levels will remain elevated
The passage outlines the role of angiotensin converting enzyme (ACE) in the renin-angiotensin-aldosterone system (RAAS). Because ACE inhibitors act on the enzyme that converts angiotensin I to angiotensin II, we would expect renin and angiotensin I to remain high because they are present before the ACE step in the RAAS pathway. The hormones present after ACE action, including angiotensin II and aldosterone, however would decrease with ACE inactivation, as would sodium reabsorption. The result is generally lower blood pressure.
We can see that inhibiting the action of ACE would cause buildup of renin and angiotensin I, and a decrease in angiotensin II, which would result in a failure to retain water.
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