L3: Tranasport Machnism

Question 1

1. How is paracellular transport defined in the context of substance transport?
   
   • a) Through the cell
   • b) Between the cell gaps
   • c) Across aquaporins
   • d) None of the above

Answer 1

B

Question 2

2. What is the primary significance of tight junctions in the tubules regarding paracellular transport?
   
   • a) Facilitate water reabsorption
   • b) Limit paracellular transport
   • c) Enhance osmotic gradients
   • d) Promote active transport

Answer 2

B

Question 3

3. Which type of transport involves the movement of substances through the cell?
   
   • a) Paracellular
   • b) Transcellular
   • c) Osmotic
   • d) Aquaporin

Answer 3

B

Question 4

4. What is the direction of substance flow in the tubular system?
   
   • a) Tubular cells to lumen
   • b) Lumen to peritubular capillary
   • c) Peritubular capillary to tubular cells
   • d) Peritubular capillary to lumen

Answer 4

B

Question 5

5. How would you describe the fluid concentration in the tubules concerning plasma?
   
   • a) Hypertonic
   • b) Isotonic
   • c) Hypotonic
   • d) Osmotic

Answer 5

B

Question 6

6. What creates the driving force for ion movement in substance transport?
   
   • a) Temperature gradient
   • b) Concentration gradient
   • c) Electrical gradient
   • d) Osmotic gradient

Answer 6

B

Question 7

7. In the first half of the proximal tubule, what is the majority of extracellular fluid (ECF) composition?
   
   • a) Hypertonic NaCl
   • b) Isotonic NaCl
   • c) Hypotonic NaCl
   • d) Hyperosmotic NaCl

Answer 7

B

Question 8

8. How is reabsorption of Na+ achieved in the proximal tubule?
   
   • a) Na/K ATPase
   • b) Aquaporin 1
   • c) Na/Hexchanger
   • d) Na/Cl- exchanger

Answer 8

A

Question 9

9. What inhibits Na/K ATPase in the reabsorption of Na+?
   
   • a) Aquaporin
   • b) Ouabain
   • c) Formic acid
   • d) GLUT2

Answer 9

B

Question 10

10. Why do we need to reabsorb HCO3- in the proximal tubule?
    - a) For buffering
    - b) To maintain osmotic pressure
    - c) To enhance electrical gradients
    - d) For energy production

Answer 10

A

Question 11

11. When do we find HCO3- in the urine?
    - a) Metabolic acidosis
    - b) Metabolic alkalosis
    - c) Diabetes mellitus
    - d) Hypertension

Answer 11

B

Question 12

12. What is the main transporter for glucose and Na+ into the cell?
    - a) SGLT1
    - b) GLUT2
    - c) Na/HCO3- cotransporter
    - d) Na/K ATPase

Answer 12

A

Question 13

13. What happens when the plasma glucose concentration increases?
    - a) Reabsorption decreases
    - b) Reabsorption remains constant
    - c) Reabsorption increases
    - d) Glucose is excreted in urine

Answer 13

C

Question 14

14. What occurs when we reach the threshold for glucose reabsorption?
    - a) Excessive glucose excretion
    - b) Increased tubular fluid volume
    - c) Glucose is retained in the cell
    - d) Glucose excretion in urine

Answer 14

D

Question 15

15. In the second half of the proximal tubule, what replaces HCO3- for Na+ reabsorption?
    - a) Glucose
    - b) Formate & Oxalate
    - c) Amino acids
    - d) Pi

Answer 15

B

Question 16

16. How is Cl- moved into the cell in the second half of the proximal tubule?
    - a) Na/Cl- exchanger
    - b) Anion/Cl- exchanger
    - c) Aquaporin 1
    - d) Na/HCO3- cotransporter

Answer 16

B

Question 17

17. Why do we have an increase in Cl- in the tubular fluid down the proximal tubule?
    - a) Cl- reabsorption
    - b) Active secretion
    - c) Na/K ATPase activity
    - d) Increased aquaporin expression

Answer 17

A

Question 18

18. What prevents the presence of proteins in normal urine?
    - a) Tight junctions
    - b) Aquaporins
    - c) Membrane selectivity in the glomerulus
    - d) Na/K ATPase

Answer 18

C

Question 19

19. How is calcium reabsorbed in the proximal tubules?
    - a) Active transport through NKCC2
    - b) Passive paracellular transport
    - c) Facilitated diffusion through aquaporins
    - d) Receptor-mediated endocytosis

Answer 19

B

Question 20

20. What triggers the secretion of metabolite products in the proximal tubule?
    - a) Na/K ATPase activity
    - b) Hormones
    - c) Membrane selectivity
    - d) Aquaporin expression

Answer 20

B

Question 21

21. What is the function of the thin descending loop of Henle?
    - a) Active sodium reabsorption
    - b) Reabsorption of water
    - c) Reabsorption of glucose
    - d) Secretion of ions

Answer 21

B

Question 22

22. What drives the movement of ions in the thin ascending loop of Henle?
    - a) Passive paracellular transport
    - b) Active sodium reabsorption
    - c) Secretion of ions
    - d) Facilitated diffusion

Answer 22

A

Question 23

23. Why is the fluid in the thick ascending loop, distal tubule, and collecting duct diluted?
    - a) Active secretion of ions
    - b) Reabsorption of water
    - c) Reabsorption of sodium and chloride
    - d) Increased aquaporin expression

Answer 23

C

Question 24

24. What inhibits NKCC2 in the thick ascending loop of Henle?
    - a) Aldosterone
    - b) Angiotensin II
    - c) Furosemide
    - d) PTH

Answer 24

C

Question 25

25. How is calcium reabsorbed in the loop of Henle? - a) Active transport in the thin descending loop - b) Paracellular pathway in the thick ascending loop - c) Facilitated diffusion through aquaporins - d) Receptor-mediated endocytosis

Answer 25

B

Question 26

26. Which cells in the distal tubule primarily reabsorb sodium through sodium epithelial channels? - a) Principal cells - b) Intercalated cells - c) Endothelial cells - d) Transitional cells

Answer 26

A

Question 27

27. What is the consequence of inhibiting NKCC2 in the thick ascending loop? - a) Increased sodium reabsorption - b) Decreased calcium reabsorption - c) Excretion of sodium and chloride - d) Diuresis

Answer 27

D

Question 28

28. How is calcium reabsorbed in the early distal tubule and connecting segment? - a) Passive paracellular transport - b) Active transcellular transport stimulated by PTH - c) Receptor-mediated endocytosis - d) Facilitated diffusion through aquaporins

Answer 28

B

Question 29

29. Why is there no water reabsorption in the distal tubule? - a) High aquaporin expression - b) Diluted fluid at this level - c) Tight junctions preventing water movement - d) Active secretion of water

Answer 29

B

Question 30

30. What is the main driving force for ion movement in the distal tubule? - a) Sodium/K ATPase - b) Potassium pump - c) Electrical gradient - d) Osmotic gradient

Answer 30

A

Question 31

31. In the distal tubule, why does inhibiting Na+ reabsorption cause hyperkalemia with acidosis? - a) Increased HCO3- reabsorption - b) Enhanced glucose excretion - c) Decreased K+ secretion - d) Elevated tubular fluid positivity

Answer 31

C

Question 32

32. Why do we need to reabsorb calcium in the early distal tubule? - a) To prevent kidney stones - b) To maintain osmotic pressure - c) To stimulate aquaporin expression - d) To regulate blood pH

Answer 32

A

Question 33

33. What triggers the secretion of organic anions and cations in the proximal tubule? - a) Na/K ATPase - b) Membrane selectivity - c) Hormones - d) Claudins

Answer 33

C

Question 34

34. In the loop of Henle, what causes the movement of cations (Na+, K+, Ca+, Mg+) through the tight junction? - a) Negative tubular fluid - b) Positive tubular fluid - c) Increased aquaporin expression - d) Active sodium reabsorption

Answer 34

B

Question 35

35. How is calcium reabsorbed in the loop of Henle? - a) Active transcellular transport - b) Passive paracellular transport - c) Receptor-mediated endocytosis - d) Secretion through aquaporins

Answer 35

A

Question 36

36. Why is calcium not reabsorbed in the thin segment of the loop of Henle? - a) Low tubular fluid positivity - b) High aquaporin expression - c) Hormone-dependent transport - d) Absence of transporters

Answer 36

D

Question 37

37. What is the result of inhibiting NKCC2 in the loop of Henle? - a) Increased reabsorption of water - b) Decreased sodium excretion - c) Increased diuresis - d) Elevated calcium reabsorption

Answer 37

C

Question 38

38. How is calcium reabsorbed in the early distal tubule and connecting segment? - a) Passive paracellular transport - b) Active transcellular transport stimulated by PTH - c) Receptor-mediated endocytosis - d) Facilitated diffusion through aquaporins

Answer 38

B

Question 39

39. In the distal tubule, what contributes to excretion of H+? - a) Increased aquaporin expression - b) Decreased sodium reabsorption - c) Elevated tubular fluid negativity - d) Active secretion of H+

Answer 39

D

Question 40

40. Why is there no water reabsorption in the distal tubule? - a) High aquaporin expression - b) Diluted fluid at this level - c) Tight junctions preventing water movement - d) Active secretion of water

Answer 40

B

Question 41

41. What is the primary function of the thick ascending loop of Henle? - a) Reabsorption of water - b) Reabsorption of Na and Cl - c) Secretion of H+ - d) Active transport of glucose

Answer 41

B

Question 42

42. How does the thick ascending loop contribute to the dilution of tubular fluid? - a) Reabsorption of water - b) Active secretion of ions - c) Reabsorption of Na and Cl - d) Increased aquaporin expression

Answer 42

C

Question 43

43. Which transporter is responsible for Na and HCO3 reabsorption in the thick ascending loop? - a) NKCC2 - b) NHE3 - c) Na/K ATPase - d) ROMK

Answer 43

A

Question 44

44. How is potassium (K+) eliminated from cells in the thick ascending loop? - a) Na/K ATPase - b) ROMK and BK channels - c) Aquaporin 1 - d) Facilitated diffusion through GLUT2

Answer 44

B

Question 45

45. What is the impact of inhibiting NKCC2 in the thick ascending loop? - a) Increased Na and Cl reabsorption - b) Decreased K+ excretion - c) Enhanced diuresis - d) Elevated aquaporin expression

Answer 45

C

Question 46

46. What causes a difference in osmolarity between the tubular fluid and the surrounding environment in the thick ascending loop? - a) Active water reabsorption - b) Movement of ions through the cell - c) Passive paracellular transport - d) Increased aquaporin expression

Answer 46

B

Question 47

47. In the thick ascending loop, what happens when water moves through aquaporin 1? - a) Osmosis - b) Facilitated diffusion - c) Solvent drag - d) Active transport

Answer 47

C

Question 48

48. Why do we need to reabsorb proteins in the proximal tubule? - a) To maintain osmotic pressure - b) To prevent proteinuria - c) To enhance glucose reabsorption - d) To stimulate aquaporin expression

Answer 48

B

Question 49

49. What are the receptors responsible for protein reabsorption in receptor-mediated endocytosis? - a) NKCC2 - b) Megalin and cubulin - c) ROMK and BK channels - d) NHE3

Answer 49

B

Question 50

50. Why do we need to reabsorb calcium in the proximal tubules? - a) To maintain osmotic pressure - b) To prevent kidney stones - c) To enhance water reabsorption - d) To regulate blood pH

Answer 50

B

Question 51

51. What is the primary route for calcium reabsorption in the proximal tubules? - a) Active transcellular transport - b) Passive paracellular transport - c) Receptor-mediated endocytosis - d) Facilitated diffusion through aquaporins

Answer 51

B

Question 52

52. How is calcium reabsorption regulated in the proximal tubules? - a) PTH and vitamin D3 - b) Aldosterone and angiotensin II - c) ROMK and BK channels - d) GLUT2

Answer 52

A

Question 53

53. What solutes need to be secreted in the proximal tubule? - a) Glucose and amino acids - b) Organic anions and cations - c) Sodium and chloride - d) Potassium and calcium

Answer 53

B

Question 54

54. Which transporters are responsible for secreting metabolite products in the proximal tubule? - a) SGLT2 and GLUT2 - b) MRP2 and OAT - c) NKCC2 and NHE3 - d) Na/K ATPase and aquaporin 1

Answer 54

B

Question 55

55. What is the function of the thin descending loop of Henle? - a) Reabsorption of glucose - b) Secretion of ions - c) Reabsorption of water - d) Active transport of amino acids

Answer 55

C

Question 56

56. What drives the movement of ions in the thin ascending loop of Henle? - a) Facilitated diffusion - b) Active sodium reabsorption - c) Passive paracellular transport - d) Increased aquaporin expression

Answer 56

C

Question 57

57. Why is the fluid in the thick ascending loop, distal tubule, and collecting duct diluted? - a) Active secretion of ions - b) Reabsorption of water - c) Reabsorption of sodium and chloride - d) Increased aquaporin expression

Answer 57

C

Question 58

58. What is the function of the thick ascending loop in the loop of Henle? - a) Reabsorption of water - b) Reabsorption of Na and Cl - c) Secretion of H+ - d) Active transport of glucose

Answer 58

B

Question 59

59. How does the thick ascending loop contribute to the dilution of tubular fluid? - a) Reabsorption of water - b) Active secretion of ions - c) Reabsorption of Na and Cl - d) Increased aquaporin expression

Answer 59

C

Question 60

60. Which transporter is responsible for Na and HCO3 reabsorption in the thick ascending loop? - a) NKCC2 - b) NHE3 - c) Na/K ATPase - d) ROMK

Answer 60

A