Question 1

Which of the following correctly describes the epithelial cell type found in the proximal convoluted tubule (PCT) of the nephron, and its functional significance?

Accepted Answer

Simple cuboidal epithelium with abundant microvilli, facilitating extensive reabsorption of water and solutes.

Question 2

Which of the following best explains the difference between cortical and juxtamedullary nephrons?

Accepted Answer

Juxtamedullary nephrons have long loops of Henle that extend deep into the medulla, playing a crucial role in establishing the medullary osmotic gradient for urine concentration.

Question 3

Which specialized cells in the juxtaglomerular complex are responsible for monitoring sodium chloride concentration in the filtrate and signaling changes in glomerular filtration rate?

Accepted Answer

Macula densa cells

Question 4

Which of the following is NOT one of the three major renal processes involved in urine formation?

Accepted Answer

Renal exocytosis

Question 5

A patient has a glomerular hydrostatic pressure ($$P_{GC}) of 55 $$mmHg, a blood colloid osmotic pressure ($$\pi_{GC}) of 30 $$mmHg, and a capsular hydrostatic pressure ($$P_{CS}) of 15 $$mmHg. What is the net filtration pressure ($$NFP) in $$this patient?

Accepted Answer

$$NFP = P_{GC} - (\pi_{GC} + P_{CS}) = 55 - (30 + 15) = 10$$ mmHg

Question 6

Which layer of the filtration membrane is primarily responsible for preventing plasma proteins from entering the filtrate?

Accepted Answer

Basement membrane (lamina densa)

Question 7

Most reabsorption of water, glucose, amino acids, and ions occurs in which part of the nephron, and by what mechanism is sodium primarily transported across the basolateral membrane of tubule cells?

Accepted Answer

Proximal convoluted tubule; sodium-potassium ATPase pump ($$Na^+/K^+-$$ATPase)

Question 8

Obligatory water reabsorption occurs in the proximal convoluted tubule and descending limb of the loop of Henle. Which channels are responsible for water transport, and which hormone regulates their expression in the collecting duct?

Accepted Answer

Aquaporins; antidiuretic hormone (ADH)

Question 9

Which segment of the loop of Henle is permeable only to water, and which segment is permeable only to solutes?

Accepted Answer

Descending limb: water only; Ascending limb: solutes only

Question 10

A patient with diabetes insipidus has a deficiency of antidiuretic hormone (ADH). What effect would this have on urine concentration and the expression of aquaporins in the collecting duct?

Accepted Answer

Urine would be more dilute; aquaporin expression would decrease.

Question 11

Which hormone increases sodium reabsorption in the distal convoluted tubule and collecting duct, and what is the physiological consequence of this action?

Accepted Answer

Aldosterone; increased blood volume and blood pressure

Question 12

Which of the following substances is primarily secreted in the distal convoluted tubule and collecting duct, and what is the significance of this secretion?

Accepted Answer

Potassium; to maintain electrolyte balance

Question 13

The countercurrent mechanism in the nephron is essential for establishing the medullary osmotic gradient. Which of the following best describes the role of the ascending and descending limbs of the loop of Henle in this process?

Accepted Answer

The descending limb is permeable to water but not solutes, while the ascending limb is permeable to solutes but not water, creating a gradient.

Question 14

Which process is responsible for the formation of concentrated urine, and what is the role of urea recycling in this process?

Accepted Answer

Facultative water reabsorption; urea recycling increases medullary osmolality, enhancing water reabsorption.

Question 15

A patient is given a drug that inhibits the $$Na^+/K^+-$$ATPase pump in the proximal tubule. What would be the expected effect on glucose reabsorption?

Accepted Answer

Glucose reabsorption would decrease because sodium gradient is diminished, impairing secondary active transport.

Question 16

Which of the following best describes the effect of increased blood colloid osmotic pressure ($$\pi_{GC}) on $$glomerular filtration rate (GFR)?

Accepted Answer

GFR decreases because the opposing force to filtration is greater.

Question 17

Which of the following scenarios would result in the formation of dilute urine?

Accepted Answer

Low levels of ADH and decreased aquaporin expression in the collecting duct.

Question 18

A patient with chronic hypertension develops damage to the filtration membrane. Which of the following is a likely consequence?

Accepted Answer

Presence of plasma proteins in the urine (proteinuria) due to loss of filtration selectivity.

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