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Question 1
Incorrect
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What effect does osmotic diuresis have on net Na+ excretion?
Your Answer: No net effect
Correct Answer: Markedly increased Na+ excretion
Explanation:Osmotic diuresis is the increase of urination rate caused by the presence of certain substances in the small tubes of the kidneys. The excretion occurs when substances such as glucose enter the kidney tubules and cannot be reabsorbed (due to a pathological state or the normal nature of the substance). The substances cause an increase in the osmotic pressure within the tubule, causing retention of water within the lumen, and thus reduces the reabsorption of water, increasing urine output (i.e. diuresis). Sodium, chloride, potassium are markedly excreted in osmotic diuresis.
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This question is part of the following fields:
- Medicine
- Renal
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Question 2
Incorrect
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What is the function of the macula densa, located in the wall of the thick ascending limb?
Your Answer: Efferent arteriolar vasoconstriction.
Correct Answer: Tubuloglomerular feedback.
Explanation:Macula densa cells sense changes in sodium chloride level, and will trigger an autoregulatory response to increase or decrease reabsorption of ions and water to the blood (as needed) in order to alter blood volume and return blood pressure to normal. Tubuloglomerular feedback is one of several mechanisms the kidney uses to regulate glomerular filtration rate (GFR). It involves the concept of purinergic signalling, in which an increased distal tubular sodium chloride concentration causes a basolateral release of adenosine from the macula densa cells. This initiates a cascade of events that ultimately brings GFR to an appropriate level.
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This question is part of the following fields:
- Medicine
- Renal
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Question 3
Incorrect
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Using the Cockcroft-Gault formula, what will the estimated creatinine clearance be of a 55 year old male who weighs 75kg and has a serum creatinine of 150mg/dL?
Your Answer: 0.33ml/min
Correct Answer: 0.59ml/min
Explanation:A commonly used surrogate marker for estimate of creatinine clearance is the Cockcroft-Gault (CG) formula, which in turn estimates GFR in ml/min:CCr = [(140-age) x Mass(kg)]/[72 x serum creatinine (mg/dL)](multiply by 0.85 for women)Therefore CCr = (85 x 75)/(72 x 150) = 0.59
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This question is part of the following fields:
- Medicine
- Renal
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Question 4
Correct
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How does the proximal convoluted tubule excrete H+?
Your Answer: Via Na+/H+ antiporter.
Explanation:H+ secretion from cells across the luminal membrane is mostly in exchange for Na+ ions, and to a small extent, through a proton ATPase. Secreted H+ react with filtered HC03- to form H2CO3.
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This question is part of the following fields:
- Medicine
- Renal
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Question 5
Correct
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Which of the following stimulate the release of aldosterone from the adrenal cortex?
Your Answer: Angiotensin 2
Explanation:Angiotensin II also stimulates the secretion of the hormone aldosterone from the adrenal cortex. Aldosterone causes the renal tubules to increase the reabsorption of sodium and water into the blood, while at the same time causing the excretion of potassium (to maintain electrolyte balance).
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This question is part of the following fields:
- Medicine
- Renal
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Question 6
Correct
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Where is angiotensinogen produced?
Your Answer: Liver
Explanation:Angiotensin is a peptide hormone that causes vasoconstriction and a subsequent increase in blood pressure. Angiotensin also stimulates the release of aldosterone from the adrenal cortex. Aldosterone promotes sodium retention in the distal nephron, in the kidney, which also drives blood pressure up. It is derived from the precursor molecule angiotensinogen, a serum globulin produced in the liver.
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This question is part of the following fields:
- Medicine
- Renal
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Question 7
Incorrect
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Erythropoietin is synthesized by which cells of the nephron?
Your Answer: Principal cells in collecting ducts
Correct Answer: Tubular interstitial cells
Explanation:Erythropoietin is produced by interstitial fibroblasts in the kidney in close association with peritubular capillary and proximal convoluted tubule. It is also produced in perisinusoidal cells in the liver. While liver production predominates in the fetal and perinatal period, renal production is predominant during adulthood.
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This question is part of the following fields:
- Medicine
- Renal
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Question 8
Correct
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Where is the majority of Mg2+ absorbed?
Your Answer: Thick ascending limb of loop of Henle.
Explanation:Although the majority of the filtered magnesium is reabsorbed within the ascending loop of Henle, it is now recognized that the distal tubule also plays an important role in magnesium conservation.
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This question is part of the following fields:
- Medicine
- Renal
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Question 9
Incorrect
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An important enzyme in renal tissue responsible for the conversion of glutamine to glutamate and the subsequent production of NH4 is called?
Your Answer: Glutamine reductase
Correct Answer: Glutaminase
Explanation:Glutaminase catalyses the following reaction:Glutamine + H2O → Glutamate + NH3
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This question is part of the following fields:
- Medicine
- Renal
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Question 10
Incorrect
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Which of the following is a physiological effect of pregnancy on the kidney?
Your Answer: Increased creatinine
Correct Answer: Decreased creatinine
Explanation:A pregnant woman may experience an increase in kidney and ureter size. The glomerular filtration rate (GFR) commonly increases by 50%, returning to normal around 20 weeks postpartum. Plasma sodium does not change because this is offset by the increase in GFR. There is decreased blood urea nitrogen (BUN) and creatinine and potentially glucosuria (due to saturated tubular reabsorption).
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This question is part of the following fields:
- Medicine
- Renal
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SESSION STATS - PERFORMANCE PER SPECIALTY
