Question 1

Which of the following best describes the primary function of the nephron loop (loop of Henle) in the kidney?

Accepted Answer

It establishes and maintains an osmotic gradient in the renal medulla, which is essential for the production of concentrated urine.

Question 2

A patient presents with glucose in their urine. According to the study materials, which condition is most likely indicated, and what is the physiological explanation?

Accepted Answer

Diabetes mellitus; blood glucose exceeds the transport maximum (Tm) for reabsorption in the renal tubules.

Question 3

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

Accepted Answer

Antidiuretic hormone (ADH)

Question 4

Given the following values, calculate the renal clearance ($$C) of a $$substance:

Urine concentration ($$U) = 10 mg/ml
$$Urine flow rate ($$V) = 2 ml/$$min
Plasma concentration ($$P) = 0.5 mg/ml

$$Use the formula:
$$
C = \frac{UV}{P}
$$
What is the renal clearance?

Accepted Answer

$$C = 40 ml/$$min

Question 5

Which of the following is NOT a function of the kidneys?

Accepted Answer

Regulation of blood glucose by insulin secretion

Question 6

A patient’s urine is found to have a high concentration of proteins (proteinuria). Which of the following is the most likely explanation based on the filtration membrane’s function?

Accepted Answer

The filtration membrane is damaged, allowing large plasma proteins to pass into the filtrate.

Question 7

Which of the following mechanisms is responsible for the autoregulation of glomerular filtration rate (GFR) in response to increased blood pressure?

Accepted Answer

Constriction of afferent arterioles via the myogenic mechanism

Question 8

Which of the following substances is used as a standard to measure glomerular filtration rate (GFR) because it is freely filtered and neither reabsorbed nor secreted by the kidneys?

Accepted Answer

Inulin

Question 9

A patient with a vegetarian diet is likely to have which of the following effects on urine pH?

Accepted Answer

Increased urine pH (more alkaline)

Question 10

Which of the following best explains why aldosterone increases blood pressure?

Accepted Answer

It increases Na+ reabsorption in the distal convoluted tubule and collecting duct, causing water to follow by osmosis.

Question 11

Which of the following is a direct result of sympathetic nervous system activation during severe blood loss?

Accepted Answer

Constriction of afferent arterioles, leading to decreased GFR

Question 12

Which of the following best describes the role of the vasa recta in the kidney?

Accepted Answer

It preserves the medullary osmotic gradient by preventing rapid removal of salt and removing reabsorbed water.

Question 13

A patient’s urine is found to contain erythrocytes (hematuria). Which of the following is the most likely cause?

Accepted Answer

Bleeding urinary tract due to trauma, kidney stones, infection, or cancer

Question 14

Which of the following events must occur for micturition (urination) to take place?

Accepted Answer

Contraction of the detrusor muscle, opening of the internal urethral sphincter, and relaxation of the external urethral sphincter

Question 15

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

Accepted Answer

It reduces blood Na+ levels, leading to decreased blood volume and blood pressure.

Question 16

Which of the following is a characteristic of the cells lining the proximal convoluted tubule (PCT), as shown in the first image?

Accepted Answer

They have dense microvilli to increase surface area for reabsorption.

Question 17

Which of the following is the correct sequence of urine flow from the nephron to the outside of the body?

Accepted Answer

Collecting duct → minor calyx → major calyx → renal pelvis → ureter → urinary bladder → urethra

Question 18

Which of the following best explains why the glomerular capillaries are more efficient at filtration than other capillary beds in the body?

Accepted Answer

They have a higher hydrostatic pressure and a highly porous filtration membrane.

Question 19

Which of the following would most likely result in a decrease in glomerular filtration rate (GFR)?

Accepted Answer

Constriction of the afferent arteriole

The Urinary System: Structure, Function, and Physiology

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