Q: Given the following data: plasma concentration of inulin = $0.5\ mg/mL$, urine concentration of inulin = $50\ mg/mL$, and urine flow rate = $2\ mL/min$, what is the GFR?

$GFR = \frac{50\ mg/mL \times 2\ mL/min}{0.5\ mg/mL} = 200\ mL/min$

Question 1

Which of the following is NOT one of the six main functions of the kidneys?

Accepted Answer

Production of bile for fat digestion

Question 2

The nephron is considered the functional unit of the kidney. Which of the following best describes its primary role?

Accepted Answer

It filters blood, reabsorbs needed substances, and secretes wastes

Question 3

Which of the following correctly traces the flow of blood through the nephron, starting at the renal artery?

Accepted Answer

Renal artery → afferent arteriole → glomerulus → efferent arteriole → peritubular capillaries → renal vein

Question 4

Fluid is considered urine when it enters which part of the nephron?

Accepted Answer

Renal pelvis

Question 5

On average, how much plasma enters the nephrons per day in a healthy adult?

Accepted Answer

180 L/day

Question 6

Which of the following equations correctly relates excretion to the three processes of the kidney?

Accepted Answer

$Excretion = Filtration - Reabsorption + Secretion$

Question 7

Which process in the nephron uses membrane proteins to move molecules across the tubule epithelium?

Accepted Answer

Reabsorption

Question 8

Which of the following best describes the filtration barrier in the renal corpuscle?

Accepted Answer

A combination of fenestrated capillary endothelium, basal lamina, and podocyte filtration slits

Question 9

Which force favors movement of fluid from the glomerulus into Bowman's capsule?

Accepted Answer

Glomerular capillary hydrostatic pressure ($P_G$)

Question 10

If the afferent arteriole constricts, what happens to the glomerular filtration rate (GFR)?

Accepted Answer

GFR decreases

Question 11

Which of the following best explains why a decrease in GFR when blood pressure falls below normal is an adaptive response?

Accepted Answer

It prevents excessive loss of water and solutes in urine

Question 12

Which of the following molecules is commonly reabsorbed in the proximal tubule via Na+-linked secondary active transport?

Accepted Answer

Glucose

Question 13

If the plasma concentration of a substance exceeds its renal threshold, what will happen?

Accepted Answer

The substance will begin to appear in the urine

Question 14

Which of the following best describes the clearance of a substance?

Accepted Answer

The volume of plasma from which a substance is completely removed per unit time

Question 15

Given the following data: plasma concentration of inulin = $0.5\ mg/mL$, urine concentration of inulin = $50\ mg/mL$, and urine flow rate = $2\ mL/min$, what is the GFR?

Accepted Answer

$GFR = \frac{50\ mg/mL 	imes 2\ mL/min}{0.5\ mg/mL} = 200\ mL/min$

Question 16

Which of the following is a characteristic of mediated transport in the nephron?

Accepted Answer

It can reach saturation at high substrate concentrations

Question 17

Which of the following best explains why the kidney filters 180 L/day if 99% of what is filtered is reabsorbed?

Accepted Answer

To allow for rapid removal of waste and fine-tuning of body fluid composition

Question 18

Which of the following best describes the role of podocytes in the glomerulus?

Accepted Answer

They form filtration slits that regulate passage of substances into Bowman's capsule

Question 19

Which of the following is the correct general equation for clearance ($C$) of a substance?

Accepted Answer

$C = \frac{[U] 	imes V}{[P]}$

Question 20

The urinary bladder can hold approximately how much urine before the urge to void is typically felt?

Accepted Answer

500 mL

Chapter 19

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