Q: If the glomerular filtration rate (GFR) is 120 ml/min, how much filtrate is produced in 24 hours? Use the formula $$ \text{Total filtrate} = \text{GFR} \times 60 \times 24 .$$

$$ 120 \times 60 \times 24 = 172,800 \text{ ml} $$

Question 1

Which of the following best describes the main function of the kidneys in the excretory system?

Accepted Answer

They filter metabolic wastes, excess water, and salts from the blood to form urine.

Question 2

A patient is experiencing dehydration. Which hormone is most likely to be released to increase water reabsorption in the collecting duct, and what is its effect on urine concentration?

Accepted Answer

Antidiuretic hormone (ADH); decreases urine volume and increases concentration

Question 3

Which structure in the nephron is primarily responsible for the filtration of blood plasma?

Accepted Answer

Glomerulus within Bowman’s capsule

Question 4

If the glomerular filtration rate (GFR) is 120 ml/min, how much filtrate is produced in 24 hours? Use the formula $$ 	ext{Total filtrate} = 	ext{GFR} 	imes 60 	imes 24 .$$

Accepted Answer

$$ 120 	imes 60 	imes 24 = 172,800 	ext{ ml} $$

Question 5

Which of the following best explains why proteins are not normally found in the glomerular filtrate?

Accepted Answer

Proteins are too large to pass through the filtration slits of the glomerulus.

Question 6

A patient has a mutation that causes the ascending limb of the loop of Henle to become permeable to water. What would be the most likely effect on urine concentration?

Accepted Answer

Urine would become more dilute because the counter-current multiplier would be disrupted.

Question 7

Which of the following is the correct sequence of blood flow through the kidney?

Accepted Answer

Renal artery → Segmental artery → Interlobar artery → Arcuate artery → Interlobular artery → Afferent arteriole → Glomerulus

Question 8

Which part of the nephron is most responsible for the reabsorption of glucose, amino acids, and the majority of sodium ions?

Accepted Answer

Proximal convoluted tubule

Question 9

A patient with high blood pressure is given a drug that inhibits angiotensin-converting enzyme (ACE). What is the expected effect on blood pressure and sodium reabsorption?

Accepted Answer

Blood pressure decreases; sodium reabsorption decreases

Question 10

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

Accepted Answer

It maintains the osmotic gradient in the medulla by counter-current exchange.

Question 11

Which of the following would most likely occur if the internal urethral sphincter failed to contract?

Accepted Answer

Urine would leak involuntarily from the bladder.

Question 12

Which of the following is a direct effect of aldosterone on the distal convoluted tubule?

Accepted Answer

Increased sodium reabsorption

Question 13

A patient with metabolic acidosis is likely to have which of the following renal responses?

Accepted Answer

Increased secretion of H+ and increased reabsorption of HCO$$_3^-$$

Question 14

Which of the following best explains why the pressure in the glomerular capillaries is higher than in other capillaries in the body?

Accepted Answer

The afferent arteriole is wider than the efferent arteriole, increasing resistance after the glomerulus.

Question 15

Which of the following is the most likely consequence of a deficiency in antidiuretic hormone (ADH)?

Accepted Answer

Production of a large volume of dilute urine

Question 16

Which of the following best describes the function of transitional epithelium in the urinary bladder?

Accepted Answer

It allows the bladder to stretch as it fills with urine.

Question 17

A patient is found to have glucose in their urine (glycosuria). Which of the following best explains this finding?

Accepted Answer

The transport maximum (Tm) for glucose reabsorption in the proximal tubule has been exceeded.

Question 18

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

Accepted Answer

Secreting renin to regulate blood pressure

Question 19

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

Accepted Answer

It decreases sodium reabsorption, lowering blood pressure.

The Urinary System and Excretory Function: Structure, Histology, and Physiology

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