Renal Physiology

Topics in this chapter

• Glomerular Filtration and Clearance
• Renal Blood Flow and Autoregulation
• Nephron Tubular Transport
• Urine Concentration and Water Balance
• Electrolyte and Hormonal Regulation
• Renal Acid–Base Regulation

Practice questions

1. Question 1Q-877E23

   A 56-year-old man with severe hypertension is started on a medication that inhibits the Na+-K+-2Cl- symporter in the thick ascending limb of the loop of Henle. Which of the following secondary transport abnormalities is most characteristic of this drug's mechanism or site of action?

   1. A.Decreased lumen-positive potential, leading to impaired paracellular reabsorption of calcium and magnesium
   2. B.Increased water permeability of the thick ascending limb
   3. C.Enhanced potassium secretion in the proximal tubule
   4. D.Direct stimulation of free water clearance in the medullary collecting duct
   See the answer and solution
2. Question 2Q-BDF6EC

   In a classic clearance study, a patient's glomerular filtration rate (GFR) is measured using inulin, and effective renal plasma flow (ERPF) is measured using para-aminohippuric acid (PAH). If the hematocrit is 40%, which of the following represents the correct method to calculate true total renal blood flow (RBF)?

   1. A.ERPF divided by (1 - Hematocrit)
   2. B.ERPF multiplied by (1 - Hematocrit)
   3. C.Inulin clearance divided by (1 - Hematocrit)
   4. D.PAH clearance multiplied by the extraction ratio of PAH
   See the answer and solution
3. Question 3Q-E1FF42

   A patient presents with nephrogenic diabetes insipidus. At which specific nephron segment does the primary defect reside in forms associated with mutations in the aquaporin-2 gene?

   1. A.Proximal convoluted tubule
   2. B.Thick ascending limb of loop of Henle
   3. C.Early distal convoluted tubule
   4. D.Collecting duct
   See the answer and solution
4. Question 4Q-BDA2C6

   Which of the following segments of the renal tubule has the highest fractional reabsorption of filtered sodium and water under normal physiological conditions?

   1. A.Proximal convoluted tubule
   2. B.Thin descending limb of loop of Henle
   3. C.Distal convoluted tubule
   4. D.Cortical collecting duct
   See the answer and solution
5. Question 5Q-13BFA7

   A decrease in renal arterial pressure triggers the myogenic mechanism of autoregulation. What is the immediate primary cellular event responsible for this intrinsic renal response?

   1. A.Stretch-activated calcium channels in vascular smooth muscle cells open, causing contraction.
   2. B.Macula densa cells sense increased chloride delivery and release adenosine.
   3. C.Renin release from juxtaglomerular cells is suppressed by cyclic AMP.
   4. D.Prostaglandins induce vasodilation of the efferent arteriole.
   See the answer and solution