$$\text{Filtration fraction} = \frac{120}{600} = 0.2$$

$$\text{Filtered load} = 2 \text{ mg/mL} \times 100 \text{ mL/min} = 200 \text{ mg/min}$$

$$\text{Excretion} = \text{Filtration} - \text{Reabsorption} + \text{Secretion}$$

$$\text{Filtered load} = 125 \text{ mL/min} \times 0.5 \text{ mg/mL} = 62.5 \text{ mg/min}$$

Question 1

Which of the following is the functional unit of the kidney responsible for filtration, reabsorption, and secretion?

Accepted Answer

Nephron

Question 2

A patient has a renal plasma flow of 600 mL/min and a glomerular filtration rate (GFR) of 120 mL/min. What is the filtration fraction?

Accepted Answer

$$	ext{Filtration fraction} = \frac{120}{600} = 0.2$$

Question 3

If the plasma concentration of substance X is 2 mg/mL and the GFR is 100 mL/min, what is the filtered load of substance X?

Accepted Answer

$$	ext{Filtered load} = 2 	ext{ mg/mL} 	imes 100 	ext{ mL/min} = 200 	ext{ mg/min}$$

Question 4

Which hormone is primarily responsible for increasing water reabsorption in the collecting duct?

Accepted Answer

Vasopressin (ADH)

Question 5

What is the correct formula to determine the excretion rate of a substance?

Accepted Answer

$$	ext{Excretion} = 	ext{Filtration} - 	ext{Reabsorption} + 	ext{Secretion}$$

Question 6

If blood pressure decreases, what happens to angiotensin II production?

Accepted Answer

Angiotensin II production increases

Question 7

A patient drinks 500 mL of water rapidly. What is the immediate (short-term) homeostatic response?

Accepted Answer

Decreased secretion of vasopressin

Question 8

Which of the following mechanisms is responsible for glucose reabsorption in the proximal tubule?

Accepted Answer

Secondary active transport via SGLT protein

Question 9

What happens when the plasma concentration of glucose exceeds the renal threshold?

Accepted Answer

Glucose begins to appear in the urine

Question 10

Which hormone is primarily responsible for sodium reabsorption in the distal nephron?

Accepted Answer

Aldosterone

Question 11

A patient has a GFR of 125 mL/min and a plasma concentration of substance Y of 0.5 mg/mL. What is the filtered load of Y?

Accepted Answer

$$	ext{Filtered load} = 125 	ext{ mL/min} 	imes 0.5 	ext{ mg/mL} = 62.5 	ext{ mg/min}$$

Question 12

Which of the following best describes the effect of increased resistance in the afferent arteriole on GFR?

Accepted Answer

GFR decreases

Question 13

What is the primary action of aldosterone in the kidney?

Accepted Answer

Increase sodium reabsorption in the distal tubule and collecting duct

Question 14

Which of the following is a short-term homeostatic response to drinking a large amount of water?

Accepted Answer

Decreased urine osmolarity

Question 15

Which process is responsible for the movement of substances from the peritubular capillaries into the renal tubule?

Accepted Answer

Secretion

Question 16

If clearance of substance Z is greater than GFR, what does this indicate about renal handling of Z?

Accepted Answer

Z is secreted

Question 17

Which of the following is a buffer system used by the kidneys to maintain acid-base balance?

Accepted Answer

Phosphate and ammonia in urine

Question 18

What is the effect of vasopressin (ADH) on the collecting duct?

Accepted Answer

Increases water permeability

Question 19

Which of the following would most likely occur in response to ingestion of hypertonic saline?

Accepted Answer

Increase in plasma osmolarity

Renal Physiology: Kidney Function, Water-Solute Balance, and Acid-Base Regulation

Study Guide - Practice Questions