Q: Which equation correctly represents the relationship between filtration, reabsorption, secretion, and excretion in the nephron?

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

Q: A patient has a plasma creatinine concentration of 1 mg/dL and a urine creatinine concentration of 100 mg/dL with a urine flow rate of 1 mL/min. What is the estimated glomerular filtration rate (GFR) in mL/min?

$$\text{GFR} = \frac{100 \times 1}{1} = 100 mL/$$min

Question 1

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

Accepted Answer

Synthesis of plasma proteins

Question 2

A patient presents with glucose in their urine (glycosuria). Which renal concept best explains why this occurs?

Accepted Answer

The plasma glucose concentration has exceeded the renal threshold

Question 3

Which structure is the functional unit of the kidney responsible for modifying filtered plasma into urine?

Accepted Answer

Nephron

Question 4

Which of the following best describes the path of blood flow through the kidney's portal system?

Accepted Answer

Afferent arteriole → glomerulus → efferent arteriole → peritubular capillaries

Question 5

Which equation correctly represents the relationship between filtration, reabsorption, secretion, and excretion in the nephron?

Accepted Answer

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

Question 6

A drug is secreted into the nephron by the organic anion transporter (OAT) family. What would happen if another drug that also uses OAT is administered simultaneously?

Accepted Answer

The secretion of both drugs would decrease due to competition

Question 7

Which pressure favors glomerular filtration in the renal corpuscle?

Accepted Answer

Capillary blood pressure ($$P_{GC})$$

Question 8

If the resistance in the afferent arteriole increases, what is the expected effect on glomerular filtration rate (GFR)?

Accepted Answer

GFR decreases

Question 9

Which process is responsible for the movement of substances from the blood into the lumen of the nephron, and where does it primarily occur?

Accepted Answer

Filtration; renal corpuscle

Question 10

A patient is severely dehydrated. What change would you expect in the osmolarity of urine and why?

Accepted Answer

Urine osmolarity increases due to increased water reabsorption

Question 11

Which of the following best describes the mechanism of sodium-linked glucose reabsorption in the proximal tubule?

Accepted Answer

Glucose is reabsorbed via secondary active transport with Na$$^+$$

Question 12

Which cells in the juxtaglomerular apparatus detect NaCl concentration in the filtrate and help regulate GFR?

Accepted Answer

Macula densa cells

Question 13

Which of the following is true regarding the composition of urine after it leaves the collecting ducts?

Accepted Answer

Its composition remains unchanged until excretion

Question 14

A patient has a plasma creatinine concentration of 1 mg/dL and a urine creatinine concentration of 100 mg/dL with a urine flow rate of 1 mL/min. What is the estimated glomerular filtration rate (GFR) in mL/min?

Accepted Answer

$$	ext{GFR} = \frac{100 	imes 1}{1} = 100 mL/$$min

Question 15

Which of the following best describes the micturition reflex?

Accepted Answer

It is a spinal reflex that can be overridden by higher brain centers

Question 16

Which of the following would most likely increase the glomerular filtration rate (GFR)?

Accepted Answer

Decreased resistance in the afferent arteriole

Question 17

Which of the following is a correct statement about the reabsorption of urea in the nephron?

Accepted Answer

Urea is reabsorbed by passive diffusion following gradients created by Na$$^+$$ reabsorption

Question 18

Which of the following best explains why plasma proteins are not normally found in the filtrate of the renal corpuscle?

Accepted Answer

They are too large to pass through the filtration slits between podocyte foot processes

Chapter 19: The Kidneys – Structure, Function, and Physiology

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