Tubular Reabsorption and Secretion: MCQs and Practice Questions

Question 1

Which mechanism is primarily responsible for glucose reabsorption in the proximal tubule?

Accepted Answer

Sodium-glucose cotransporter (SGLT2)

Answer

Simple diffusion

Answer

Facilitated diffusion

Answer

Active transport

Question 2

Which hormone primarily increases calcium reabsorption in the distal convoluted tubule?

Accepted Answer

Parathyroid hormone

Answer

Calcitonin

Answer

Aldosterone

Answer

Antidiuretic hormone

Question 3

What is the main function of the thick ascending limb of the loop of Henle?

Accepted Answer

Reabsorption of sodium and chloride ions

Answer

Secretion of potassium ions

Answer

Reabsorption of water

Answer

Secretion of bicarbonate ions

Question 4

Which hormone increases the collecting duct's permeability to water?

Accepted Answer

Antidiuretic hormone

Answer

Aldosterone

Answer

Parathyroid hormone

Answer

Calcitonin

Question 5

How are sodium ions primarily reabsorbed in the collecting duct?

Accepted Answer

Sodium-potassium chloride cotransporter

Answer

Sodium-potassium ATPase

Answer

Sodium-hydrogen exchanger

Answer

Sodium-chloride cotransporter

Question 6

In the proximal tubule of the kidney, which transport mechanism is primarily responsible for reabsorbing sodium ions?

Accepted Answer

Active transport via the Na+/K+-ATPase pump

Answer

Passive diffusion along a concentration gradient

Answer

Facilitated diffusion via specific carrier proteins

Answer

Bulk flow of water along with sodium ions

Question 7

Which segment of the nephron is primarily responsible for reabsorbing glucose?

Accepted Answer

Proximal tubule

Answer

Loop of Henle

Answer

Distal tubule

Answer

Collecting duct

Question 8

Which ion is actively reabsorbed by the proximal tubule through primary active transport?

Accepted Answer

Sodium

Answer

Potassium

Answer

Chloride

Answer

Bicarbonate

Question 9

Which hormone is responsible for stimulating the reabsorption of calcium in the distal tubule?

Accepted Answer

Parathyroid hormone

Answer

Antidiuretic hormone

Answer

Aldosterone

Answer

Insulin

Question 10

Which characteristic of the descending limb of the loop of Henle enables it to contribute to the maintenance of medullary hypertonicity?

Accepted Answer

Permeability to water and impermeability to sodium ions

Answer

Active transport of sodium ions from the lumen into the interstitium

Answer

Impermeability to water and permeability to sodium ions

Answer

Active transport of water from the interstitium into the lumen

Question 11

Which mechanism is primarily responsible for the reabsorption of glucose in the proximal tubule?

Accepted Answer

Sodium-glucose cotransporter (SGLT2)

Answer

Glucose transporter type 1 (GLUT1)

Answer

Facilitated diffusion

Answer

Passive diffusion

Question 12

Which ion is actively secreted into the lumen of the proximal tubule, playing a significant role in acid-base balance?

Accepted Answer

Hydrogen ions (H+)

Answer

Sodium ions (Na+)

Answer

Potassium ions (K+)

Answer

Chloride ions (Cl-)

Question 13

The primary reason the loop of Henle is crucial for maintaining the body's water balance is that it:

Accepted Answer

Creates a concentration gradient in the medulla

Answer

Secretes antidiuretic hormone (ADH)

Answer

Reabsorbs sodium and water

Answer

Filters waste products from the blood

Question 14

Which hormone enhances water reabsorption in the collecting ducts, leading to decreased urine output?

Accepted Answer

Antidiuretic hormone (ADH)

Answer

Aldosterone

Answer

Insulin

Answer

Parathyroid hormone (PTH)

Question 15

Which ion is primarily reabsorbed in the distal tubule via the epithelial sodium channel (ENaC)?

Accepted Answer

Sodium (Na+)

Answer

Potassium (K+)

Answer

Chloride (Cl-)

Answer

Hydrogen (H+)

Question 16

The secretion of potassium ions (K+) in the collecting ducts is predominantly regulated by which hormone?

Accepted Answer

Aldosterone

Answer

Cortisol

Answer

Insulin

Answer

Antidiuretic hormone (ADH)

Question 17

Which mechanism is responsible for the reabsorption of calcium ions (Ca2+) in the proximal tubule?

Accepted Answer

Sodium-calcium exchanger

Answer

Passive diffusion

Answer

Facilitated diffusion

Answer

Active transport

Question 18

The reabsorption of amino acids in the proximal tubule occurs primarily through:

Accepted Answer

Sodium-amino acid cotransporters

Answer

Glucose-amino acid cotransporters

Answer

Facilitated diffusion

Answer

Active transport

Question 19

How does the countercurrent multiplier system in the loop of Henle contribute to urine concentration?

Accepted Answer

Establishes a high solute concentration in the medullary interstitium

Answer

Increases glomerular filtration rate

Answer

Decreases tubular reabsorption rate

Answer

Increases tubular secretion rate

Question 20

Which mechanism is primarily responsible for the reabsorption of glucose in the proximal tubule?

Accepted Answer

Facilitated diffusion

Answer

Passive diffusion

Answer

Active transport

Answer

Pinocytosis

Question 21

Which hormone exerts the primary stimulatory effect on sodium reabsorption in the distal tubule?

Accepted Answer

Aldosterone

Answer

Antidiuretic hormone (ADH)

Answer

Parathyroid hormone (PTH)

Answer

Atrial natriuretic peptide (ANP)

Question 22

In which segment of the nephron does the predominant reabsorption of bicarbonate ions occur?

Accepted Answer

Proximal tubule

Answer

Loop of Henle

Answer

Distal tubule

Answer

Collecting duct

Question 23

Which of the following is a direct effect of increased parathyroid hormone (PTH) secretion on renal transport?

Accepted Answer

Increased calcium reabsorption in the proximal tubule

Answer

Increased phosphate reabsorption in the proximal tubule

Answer

Increased magnesium reabsorption in the loop of Henle

Answer

Decreased water reabsorption in the collecting duct

Question 24

What is the primary physiological function of the loop of Henle in the context of tubular reabsorption?

Accepted Answer

Establishment of a concentration gradient for solute reabsorption

Answer

Secretion of potassium ions into the tubular fluid

Answer

Reabsorption of bicarbonate ions

Answer

Regulation of renin production

Question 25

What is the predominant factor influencing water reabsorption in the proximal tubule?

Accepted Answer

Osmotic pressure

Answer

Hydrostatic pressure

Answer

Protein concentration

Answer

Hormonal regulation

Question 26

Which transport mechanism is primarily responsible for calcium reabsorption in the distal tubule?

Accepted Answer

Active transport

Answer

Passive diffusion

Answer

Paracellular transport

Answer

Vesicular transport

Question 27

The main function of the Loop of Henle in water reabsorption is to:

Accepted Answer

Establish a concentration gradient in the renal medulla

Answer

Reabsorb sodium (Na+) and chloride (Cl-) ions

Answer

Secrete hydrogen ions (H+)

Answer

Regulate potassium (K+) ion levels

Question 28

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

Accepted Answer

Antidiuretic hormone (ADH)

Answer

Aldosterone

Answer

Parathyroid hormone (PTH)

Answer

Thyroid hormone

Question 29

The predominant mechanism for sodium (Na+) reabsorption in the proximal tubule is:

Accepted Answer

Cotransport

Answer

Passive diffusion

Answer

Facilitated diffusion

Answer

Active transport

Question 30

In the countercurrent multiplication system of the Loop of Henle, the descending limb plays a crucial role by being:

Accepted Answer

Impermeable to water, allowing sodium (Na+) concentration

Answer

Permeable to water, allowing sodium (Na+) dilution

Answer

Secreting chloride (Cl-) ions, creating an electrochemical gradient

Answer

Reabsorbing sodium (Na+) ions, creating an osmotic gradient

Question 31

Which of the following substances is NOT reabsorbed in the proximal tubule?

Accepted Answer

Creatinine

Answer

Glucose

Answer

Amino acids

Answer

Phosphate

Question 32

The hormone that inhibits sodium (Na+) reabsorption in the collecting duct is:

Accepted Answer

Atrial natriuretic peptide (ANP)

Answer

Antidiuretic hormone (ADH)

Answer

Aldosterone

Answer

Parathyroid hormone (PTH)

Question 33

In the proximal tubule, which ion is primarily reabsorbed via the Na+/K+/2Cl- cotransporter?

Accepted Answer

Chloride

Answer

Sodium

Answer

Potassium

Answer

Bicarbonate

Question 34

Which cotransporter is responsible for the active transport of glucose from the proximal tubule lumen to the blood?

Accepted Answer

Sodium-glucose cotransporter 1 (SGLT1)

Answer

Sodium-glucose cotransporter 2 (SGLT2)

Answer

Glucose transporter 1 (GLUT1)

Answer

Glucose transporter 4 (GLUT4)

Question 35

Which hormone stimulates the reabsorption of calcium in the distal tubule?

Accepted Answer

Parathyroid hormone (PTH)

Answer

Calcitonin

Answer

Antidiuretic hormone (ADH)

Answer

Aldosterone

Question 36

Which substance is actively secreted into the proximal tubule lumen via the organic acid transporter 1 (OAT1)?

Accepted Answer

Urea

Answer

Creatinine

Answer

Glucose

Answer

Sodium

Question 37

Which mechanism establishes the transepithelial voltage gradient in the distal tubule?

Accepted Answer

Sodium-potassium pump (Na+/K+-ATPase)

Answer

Chloride channel

Answer

Potassium channel

Answer

Water channel (aquaporin)

Question 38

Which hormone inhibits water reabsorption in the collecting duct?

Accepted Answer

Atrial natriuretic peptide (ANP)

Answer

Antidiuretic hormone (ADH)

Answer

Aldosterone

Answer

Angiotensin II

Question 39

Which condition is characterized by increased water reabsorption in the distal tubule?

Accepted Answer

Syndrome of inappropriate antidiuretic hormone secretion (SIADH)

Answer

Diabetes insipidus

Answer

Renal failure

Answer

Addison's disease

Question 40

A patient presents with hypokalemia. Which of the following processes in the nephron is most likely impaired, leading to this electrolyte imbalance?

Accepted Answer

Reduced reabsorption of potassium in the distal convoluted tubule.

Answer

Impaired filtration of potassium in the glomerulus.

Answer

Excessive secretion of sodium in the proximal tubule.

Answer

Increased reabsorption of water in the collecting duct.

Question 41

Which of the following hormones directly influences sodium reabsorption in the proximal tubule?

Accepted Answer

Aldosterone

Answer

Antidiuretic hormone (ADH)

Answer

Parathyroid hormone (PTH)

Answer

Insulin

Question 42

A patient with diabetes mellitus is experiencing polyuria. Which of the following mechanisms is primarily responsible for this increased urine output?

Accepted Answer

Reduced reabsorption of water in the collecting duct due to decreased sensitivity to antidiuretic hormone (ADH).

Answer

Increased production of glucose by the liver.

Answer

Increased filtration rate in the glomerulus.

Answer

Excessive secretion of potassium in the distal tubule.

Question 43

Which of the following substances is primarily secreted in the proximal tubule?

Accepted Answer

Hydrogen ions (H+)

Answer

Water

Answer

Glucose

Answer

Sodium (Na+)

Question 44

What is the primary mechanism by which glucose is reabsorbed in the proximal tubule?

Accepted Answer

Secondary active transport coupled with sodium reabsorption.

Answer

Pinocytosis.

Answer

Facilitated diffusion.

Answer

Simple diffusion.

Question 45

Which of the following factors directly influences the reabsorption of water in the collecting duct?

Accepted Answer

Antidiuretic hormone (ADH) concentration.

Answer

Plasma calcium levels.

Answer

Blood glucose levels.

Answer

Blood pressure.

Question 46

A patient with severe dehydration is experiencing a decrease in urine output. Which of the following processes in the nephron is most likely responsible for this?

Accepted Answer

Increased water reabsorption in the collecting duct.

Answer

Decreased filtration rate in the glomerulus.

Answer

Increased reabsorption of sodium in the proximal tubule.

Answer

Increased secretion of potassium in the distal tubule.

Question 47

Which of the following best describes the role of the proximal tubule in maintaining acid-base balance?

Accepted Answer

Reabsorption of bicarbonate (HCO3-) and secretion of hydrogen ions (H+).

Answer

Reabsorption of glucose and secretion of urea.

Answer

Reabsorption of potassium and secretion of sodium.

Answer

Secretion of aldosterone and reabsorption of water.

Question 48

Which substance is actively secreted into the proximal tubule, contributing to its elimination from the body?

Accepted Answer

Creatinine

Answer

Bicarbonate

Answer

Sodium

Answer

Glucose

Question 49

In the distal tubule, how does the hormone aldosterone regulate sodium reabsorption, influencing electrolyte balance?

Accepted Answer

By enhancing the expression and activity of sodium-potassium pumps

Answer

By inhibiting the activity of sodium-hydrogen exchangers

Answer

By stimulating the production of aquaporins

Question 50

Which hormone, when released, stimulates water reabsorption in the collecting ducts, promoting fluid conservation?

Accepted Answer

Antidiuretic hormone (ADH)

Answer

Parathyroid hormone (PTH)

Answer

Atrial natriuretic peptide (ANP)

Answer

Aldosterone

Question 51

Which mechanism is responsible for the reabsorption of organic anions in the proximal tubule, facilitating the removal of waste products and toxins?

Accepted Answer

Organic anion transporters (OATs)

Answer

Sodium-hydrogen exchangers

Answer

Aquaporins

Answer

Sodium-glucose cotransporter (SGLT2)

Question 52

Which hormone is responsible for promoting calcium reabsorption in the distal convoluted tubule (DCT), influencing calcium homeostasis?

Accepted Answer

Parathyroid hormone (PTH)

Answer

Antidiuretic hormone (ADH)

Answer

Aldosterone

Answer

Atrial natriuretic peptide (ANP)