Question 1

Which of the following best describes the difference between osmolarity and tonicity?

Accepted Answer

Osmolarity measures the total concentration of solute particles, while tonicity describes the effect of a solution on cell volume.

Question 2

A patient receives an intravenous infusion of 5% dextrose in water. Which statement best describes the effect of this solution on red blood cells after infusion?

Accepted Answer

The solution is isotonic in the bag but becomes hypotonic in the body, causing cells to swell.

Question 3

Which of the following is NOT a primary homeostatic function of the vertebrate kidney?

Accepted Answer

Synthesis of plasma proteins

Question 4

Which of the following equations correctly represents the calculation of net filtration pressure ($$P_{net}) in $$the glomerulus?

Accepted Answer

$$P_{net} = P_{GC} - \pi_{GC} - P_{BC}$$

Question 5

A drug that constricts the afferent arteriole of the glomerulus will have what effect on glomerular filtration rate (GFR)?

Accepted Answer

Decrease GFR by decreasing blood flow into the glomerulus

Question 6

Which hormone increases water reabsorption in the collecting duct by stimulating the insertion of aquaporins into the apical membrane?

Accepted Answer

Vasopressin (ADH)

Question 7

A patient with severe dehydration will exhibit which of the following physiological responses?

Accepted Answer

Increased vasopressin secretion and increased thirst

Question 8

Which of the following best describes the countercurrent multiplier system in the loop of Henle?

Accepted Answer

It creates a gradient of increasing osmolarity in the medulla by active transport of solutes in the ascending limb.

Question 9

Which of the following is a direct effect of aldosterone on renal principal cells?

Accepted Answer

Increased synthesis and activity of ENaC and Na+/K+ ATPase

Question 10

A patient is given an ACE inhibitor. Which of the following effects would you expect?

Accepted Answer

Decreased aldosterone secretion and decreased sodium reabsorption

Question 11

Which of the following best explains why only about 1% of the filtered fluid by the kidneys is excreted as urine?

Accepted Answer

Most of the filtered fluid is reabsorbed back into the blood.

Question 12

Which of the following would most likely result from a loss of function mutation in the gene encoding the epithelial sodium channel (ENaC) in the distal nephron?

Accepted Answer

Decreased sodium reabsorption and possible hypotension

Question 13

Which of the following is a function of the juxtaglomerular apparatus?

Accepted Answer

Paracrine regulation of GFR and secretion of renin

Question 14

Which of the following best describes the effect of atrial natriuretic peptide (ANP) on kidney function?

Accepted Answer

It promotes natriuresis by increasing GFR and decreasing sodium reabsorption.

Question 15

A patient with diabetes insipidus is most likely to present with which of the following symptoms?

Accepted Answer

High urine output and low urine osmolarity

Question 16

Which of the following best explains why urea contributes to the high osmolarity of the renal medulla?

Accepted Answer

Urea passively diffuses into the medulla, increasing interstitial osmolarity.

Question 17

Which of the following is the primary mechanism by which the kidneys regulate plasma potassium levels?

Accepted Answer

Regulation of potassium secretion in the distal nephron under the influence of aldosterone

Question 18

A patient with chronic diarrhea is at risk for which of the following electrolyte disturbances?

Accepted Answer

Hypokalemia due to increased potassium loss

Question 19

Which of the following best describes the effect of increased sympathetic nervous system activity on the kidneys during severe hemorrhage?

Accepted Answer

Vasoconstriction of both afferent and efferent arterioles, reducing GFR to conserve fluid

Human Physiology: The Renal System and Fluid & Electrolyte Balance

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