MCQs on Human Renal Physiology

4.8
(5682)

1. What is the primary function of the kidneys?

  • a) Production of red blood cells
  • b) Regulation of blood pressure
  • c) Excretion of metabolic waste products
  • d) Synthesis of hormones

Answer: c) Excretion of metabolic waste products
Explanation: The kidneys filter blood to remove metabolic waste products like urea, creatinine, and excess ions. They also maintain fluid, electrolyte, and acid-base balance, ensuring the proper functioning of the body's internal environment.

2. What is the structural and functional unit of the kidney?

  • a) Alveolus
  • b) Nephron
  • c) Lobule
  • d) Glomerulus

Answer: b) Nephron
Explanation: The nephron is the structural and functional unit of the kidney. It consists of a glomerulus and renal tubules, which work together to filter blood, reabsorb essential substances, and excrete waste as urine.

3. Which process occurs at the glomerulus?

  • a) Tubular reabsorption
  • b) Tubular secretion
  • c) Filtration
  • d) Excretion

Answer: c) Filtration
Explanation: Filtration occurs at the glomerulus, where blood pressure forces plasma, electrolytes, and small molecules out of the blood and into Bowman's capsule, forming the filtrate that enters the nephron.

4. What drives glomerular filtration?

  • a) Osmotic pressure
  • b) Hydrostatic pressure
  • c) Active transport
  • d) Diffusion

Answer: b) Hydrostatic pressure
Explanation: The hydrostatic pressure of blood within the glomerular capillaries drives the filtration process, pushing water and solutes from the blood into Bowman's capsule while retaining blood cells and large proteins.

5. Which of the following substances is normally completely reabsorbed in the proximal convoluted tubule?

  • a) Urea
  • b) Glucose
  • c) Creatinine
  • d) Uric acid

Answer: b) Glucose
Explanation: Under normal conditions, all filtered glucose is reabsorbed in the proximal convoluted tubule through sodium-glucose transporters. The presence of glucose in urine indicates impaired reabsorption or hyperglycemia.

6. What is the role of the loop of Henle in the kidney?

  • a) Filtration of blood
  • b) Secretion of potassium
  • c) Concentration of urine
  • d) Production of erythropoietin

Answer: c) Concentration of urine
Explanation: The loop of Henle establishes a concentration gradient in the renal medulla, allowing for the reabsorption of water and concentration of urine, essential for maintaining fluid balance.

7. Which hormone increases water reabsorption in the kidneys?

  • a) Aldosterone
  • b) Antidiuretic hormone (ADH)
  • c) Cortisol
  • d) Parathyroid hormone

Answer: b) Antidiuretic hormone (ADH)
Explanation: ADH, also called vasopressin, acts on the collecting ducts to increase water reabsorption, reducing urine volume and conserving body water during dehydration or low blood pressure conditions.

8. Where is aldosterone secreted from?

  • a) Pancreas
  • b) Adrenal cortex
  • c) Hypothalamus
  • d) Posterior pituitary

Answer: b) Adrenal cortex
Explanation: Aldosterone is secreted by the adrenal cortex. It promotes sodium reabsorption and potassium excretion in the distal convoluted tubule and collecting ducts, helping regulate blood pressure and fluid balance.

9. What role does the juxtaglomerular apparatus (JGA) play in kidney function?

  • a) Filtration of blood
  • b) Regulation of blood pressure
  • c) Production of erythropoietin
  • d) Reabsorption of glucose

Answer: b) Regulation of blood pressure
Explanation: The JGA regulates blood pressure through the renin-angiotensin-aldosterone system (RAAS). When blood pressure drops, it releases renin, which triggers processes that increase blood pressure and fluid retention.

10. What is the primary function of renin?

  • a) Lowering blood pressure
  • b) Breaking down proteins
  • c) Activating angiotensinogen
  • d) Increasing potassium excretion

Answer: c) Activating angiotensinogen
Explanation: Renin, released by the kidneys, converts angiotensinogen (produced by the liver) into angiotensin I, which is further converted to angiotensin II, a potent vasoconstrictor that raises blood pressure.

11. What part of the nephron is primarily responsible for the reabsorption of sodium, water, and glucose?

  • a) Distal convoluted tubule
  • b) Loop of Henle
  • c) Proximal convoluted tubule
  • d) Collecting duct

Answer: c) Proximal convoluted tubule
Explanation: The proximal convoluted tubule reabsorbs approximately 65% of sodium and water, along with nearly all filtered glucose and amino acids. This reabsorption is crucial for maintaining fluid and electrolyte balance.

12. What is the function of the distal convoluted tubule?

  • a) Filtration of blood
  • b) Reabsorption of large molecules
  • c) Regulation of sodium, potassium, and pH
  • d) Production of erythropoietin

Answer: c) Regulation of sodium, potassium, and pH
Explanation: The distal convoluted tubule regulates sodium and potassium reabsorption and hydrogen ion secretion, which helps maintain acid-base balance and electrolyte homeostasis.

13. Which mechanism helps create the concentration gradient in the renal medulla?

  • a) Countercurrent multiplication
  • b) Active transport
  • c) Osmotic diffusion
  • d) Bulk filtration

Answer: a) Countercurrent multiplication
Explanation: The countercurrent multiplication system, involving the loop of Henle, generates a concentration gradient in the renal medulla, which is critical for water reabsorption and the production of concentrated urine.

14. What is the main nitrogenous waste excreted by the kidneys?

  • a) Ammonia
  • b) Creatinine
  • c) Uric acid
  • d) Urea

Answer: d) Urea
Explanation: Urea, formed in the liver during protein metabolism, is the primary nitrogenous waste product excreted by the kidneys. It is less toxic than ammonia and efficiently removed from the bloodstream.

15. Which hormone directly stimulates sodium reabsorption in the kidneys?

  • a) ADH
  • b) Aldosterone
  • c) Renin
  • d) Angiotensin II

Answer: b) Aldosterone
Explanation: Aldosterone acts on the distal convoluted tubule and collecting ducts, promoting sodium reabsorption and potassium excretion, which plays a key role in maintaining blood pressure and fluid balance.

16. What is the primary role of angiotensin II in the renal system?

  • a) Increase potassium excretion
  • b) Promote water loss
  • c) Constrict blood vessels and stimulate aldosterone secretion
  • d) Decrease sodium absorption

Answer: c) Constrict blood vessels and stimulate aldosterone secretion
Explanation: Angiotensin II is a potent vasoconstrictor that raises blood pressure. It also stimulates the release of aldosterone, promoting sodium retention and water reabsorption.

17. Which substance is typically not filtered by the glomerulus?

  • a) Glucose
  • b) Amino acids
  • c) Large proteins
  • d) Sodium

Answer: c) Large proteins
Explanation: Large proteins are typically too large to pass through the filtration barrier of the glomerulus. The presence of proteins in urine often indicates glomerular damage or disease.

18. What does the term "renal clearance" refer to?

  • a) The ability of the kidney to filter proteins
  • b) The rate at which the kidney excretes a substance
  • c) The filtration capacity of the glomerulus
  • d) The volume of plasma filtered per minute

Answer: b) The rate at which the kidney excretes a substance
Explanation: Renal clearance is the volume of plasma completely cleared of a specific substance by the kidneys per unit time. It provides valuable information about kidney function and filtration efficiency.

19. What is the primary stimulus for the release of ADH?

  • a) High blood pressure
  • b) Low blood glucose levels
  • c) Increased plasma osmolality
  • d) Low potassium levels

Answer: c) Increased plasma osmolality
Explanation: ADH release is stimulated by increased plasma osmolality, which indicates dehydration. ADH promotes water reabsorption in the kidneys, diluting the plasma and restoring osmotic balance.

20. What is the normal range for glomerular filtration rate (GFR) in a healthy adult?

  • a) 30-60 mL/min
  • b) 60-90 mL/min
  • c) 90-120 mL/min
  • d) 150-200 mL/min

Answer: c) 90-120 mL/min
Explanation: The normal GFR in a healthy adult is approximately 90-120 mL/min. A decrease in GFR is a marker of impaired kidney function or chronic kidney disease.

21. What does the renal medulla primarily contain?

  • a) Glomeruli
  • b) Renal pyramids
  • c) Bowman's capsule
  • d) Proximal convoluted tubules

Answer: b) Renal pyramids
Explanation: The renal medulla contains renal pyramids, which consist of loops of Henle and collecting ducts. These structures are essential for concentrating urine and regulating water balance in the body.

22. What role does the macula densa play in kidney function?

  • a) Filters blood
  • b) Regulates blood glucose
  • c) Detects sodium concentration in the distal tubule
  • d) Reabsorbs water

Answer: c) Detects sodium concentration in the distal tubule
Explanation: The macula densa, part of the juxtaglomerular apparatus, senses sodium levels in the filtrate. If sodium levels are low, it signals the release of renin to help maintain blood pressure and fluid balance.

23. What happens to potassium in the collecting ducts under the influence of aldosterone?

  • a) Reabsorbed
  • b) Secreted
  • c) Buffered
  • d) Filtered

Answer: b) Secreted
Explanation: Aldosterone stimulates the secretion of potassium into the urine in the collecting ducts, helping regulate serum potassium levels and maintaining electrolyte homeostasis.

24. What is the significance of the renal threshold for glucose?

  • a) Indicates glucose storage capacity
  • b) Defines the minimum blood glucose level
  • c) Indicates the blood glucose level at which glucose appears in urine
  • d) Regulates glycogen breakdown

Answer: c) Indicates the blood glucose level at which glucose appears in urine
Explanation: The renal threshold for glucose is around 180 mg/dL. Beyond this level, glucose transporters become saturated, and glucose starts appearing in the urine, a condition known as glycosuria.

25. Which part of the nephron is impermeable to water?

  • a) Proximal convoluted tubule
  • b) Descending limb of the loop of Henle
  • c) Ascending limb of the loop of Henle
  • d) Collecting duct

Answer: c) Ascending limb of the loop of Henle
Explanation: The ascending limb of the loop of Henle is impermeable to water but actively reabsorbs sodium, potassium, and chloride ions, contributing to the creation of the medullary concentration gradient.

26. What role does erythropoietin (EPO) play in the body?

  • a) Regulates calcium metabolism
  • b) Stimulates red blood cell production
  • c) Controls blood glucose levels
  • d) Maintains potassium balance

Answer: b) Stimulates red blood cell production
Explanation: Erythropoietin, primarily produced by the kidneys, stimulates the bone marrow to produce red blood cells in response to hypoxia or low oxygen levels in the blood.

27. What is a key feature of chronic kidney disease (CKD)?

  • a) Decreased protein excretion
  • b) Elevated glomerular filtration rate
  • c) Persistent proteinuria
  • d) Increased erythropoietin production

Answer: c) Persistent proteinuria
Explanation: Persistent proteinuria is a hallmark of chronic kidney disease. It results from damage to the glomerular filtration barrier, allowing proteins to leak into the urine.

28. Which ion is critical for maintaining acid-base balance in the kidney?

  • a) Sodium
  • b) Potassium
  • c) Bicarbonate
  • d) Calcium

Answer: c) Bicarbonate
Explanation: Bicarbonate is essential for buffering blood pH. The kidneys regulate acid-base balance by reabsorbing bicarbonate and excreting hydrogen ions to maintain a stable blood pH.

29. How does the kidney help regulate blood pressure?

  • a) By secreting insulin
  • b) By producing renin
  • c) By releasing glucagon
  • d) By excreting calcium

Answer: b) By producing renin
Explanation: The kidneys regulate blood pressure by releasing renin, which activates the renin-angiotensin-aldosterone system (RAAS), leading to vasoconstriction and increased sodium and water retention.

30. What is the primary function of the vasa recta in the kidney?

  • a) Blood filtration
  • b) Water excretion
  • c) Maintenance of the medullary concentration gradient
  • d) Synthesis of hormones

Answer: c) Maintenance of the medullary concentration gradient
Explanation: The vasa recta are capillaries that surround the loop of Henle. They play a crucial role in maintaining the concentration gradient in the medulla, essential for water reabsorption.

31. What is the main role of the loop of Henle?

  • a) Filtration of plasma
  • b) Reabsorption of glucose
  • c) Creation of a concentration gradient for water reabsorption
  • d) Production of aldosterone

Answer: c) Creation of a concentration gradient for water reabsorption
Explanation: The loop of Henle creates a concentration gradient in the medulla by countercurrent multiplication. This gradient allows for the reabsorption of water from the collecting ducts, helping concentrate urine.

32. Which segment of the nephron is most permeable to water?

  • a) Proximal convoluted tubule
  • b) Descending limb of the loop of Henle
  • c) Ascending limb of the loop of Henle
  • d) Distal convoluted tubule

Answer: b) Descending limb of the loop of Henle
Explanation: The descending limb of the loop of Henle is highly permeable to water but not to solutes, leading to water reabsorption and increased filtrate osmolarity.

33. What is the role of the juxtaglomerular cells in the kidney?

  • a) Secrete aldosterone
  • b) Reabsorb glucose
  • c) Release renin
  • d) Excrete urea

Answer: c) Release renin
Explanation: Juxtaglomerular cells, located in the afferent arteriole, secrete renin in response to low blood pressure or low sodium levels, initiating the renin-angiotensin-aldosterone system (RAAS).

34. What is the significance of aquaporins in the renal system?

  • a) Aid in protein transport
  • b) Facilitate water reabsorption
  • c) Maintain potassium balance
  • d) Excrete urea

Answer: b) Facilitate water reabsorption
Explanation: Aquaporins are water channels in the cell membranes of the nephron, particularly in the collecting ducts, that enable water reabsorption under the influence of antidiuretic hormone (ADH).

35. What condition results from the inability of the kidney to concentrate urine?

  • a) Diabetes mellitus
  • b) Nephrotic syndrome
  • c) Diabetes insipidus
  • d) Chronic glomerulonephritis

Answer: c) Diabetes insipidus
Explanation: Diabetes insipidus occurs when the kidneys fail to concentrate urine due to a deficiency of ADH or a lack of response to ADH, leading to excessive water loss and dilute urine.

36. Which substance is used to measure renal plasma flow?

  • a) Creatinine
  • b) Inulin
  • c) Para-aminohippuric acid (PAH)
  • d) Urea

Answer: c) Para-aminohippuric acid (PAH)
Explanation: PAH is used to measure renal plasma flow because it is almost completely removed from the plasma during a single passage through the kidneys, providing an accurate assessment.

37. What is the normal pH range of urine?

  • a) 3.0 to 4.0
  • b) 4.5 to 8.0
  • c) 7.0 to 9.5
  • d) 8.0 to 9.5

Answer: b) 4.5 to 8.0
Explanation: The normal pH range of urine is 4.5 to 8.0. The acidity or alkalinity of urine can vary depending on diet, metabolic status, and underlying medical conditions.

38. What structure drains urine from the kidney to the bladder?

  • a) Urethra
  • b) Collecting ducts
  • c) Ureters
  • d) Renal pelvis

Answer: c) Ureters
Explanation: Ureters are muscular tubes that transport urine from the renal pelvis of the kidneys to the urinary bladder through peristaltic contractions.

39. What is the typical daily urine output in a healthy adult?

  • a) 200-500 mL
  • b) 800-2000 mL
  • c) 3000-4000 mL
  • d) Less than 200 mL

Answer: b) 800-2000 mL
Explanation: The normal daily urine output for a healthy adult ranges from 800 to 2000 mL, depending on fluid intake, environmental conditions, and metabolic factors.

40. Which renal function test specifically assesses glomerular filtration rate (GFR)?

  • a) Serum creatinine
  • b) Blood urea nitrogen (BUN)
  • c) Creatinine clearance test
  • d) Urine protein test

Answer: c) Creatinine clearance test
Explanation: The creatinine clearance test measures the amount of creatinine cleared from the blood by the kidneys over time, providing a direct assessment of the glomerular filtration rate (GFR).

41. What hormone regulates water reabsorption in the collecting ducts of the nephron?

  • a) Aldosterone
  • b) Renin
  • c) Antidiuretic hormone (ADH)
  • d) Erythropoietin

Answer: c) Antidiuretic hormone (ADH)
Explanation: ADH, also known as vasopressin, increases the permeability of the collecting ducts to water by promoting the insertion of aquaporins, leading to increased water reabsorption and concentrated urine.

42. Which ion plays a critical role in maintaining the acid-base balance in the kidney?

  • a) Sodium
  • b) Potassium
  • c) Hydrogen
  • d) Calcium

Answer: c) Hydrogen
Explanation: The kidneys help maintain acid-base balance by secreting hydrogen ions and reabsorbing bicarbonate. This process keeps the blood pH within the normal range of 7.35 to 7.45.

43. What effect does the sympathetic nervous system have on renal function?

  • a) Increases urine output
  • b) Reduces renin secretion
  • c) Decreases renal blood flow
  • d) Enhances glomerular filtration

Answer: c) Decreases renal blood flow
Explanation: The sympathetic nervous system causes vasoconstriction of renal blood vessels, decreasing renal blood flow and GFR, which conserves fluid and maintains blood pressure during stress.

44. What is the functional unit of the kidney?

  • a) Glomerulus
  • b) Loop of Henle
  • c) Nephron
  • d) Renal pyramid

Answer: c) Nephron
Explanation: The nephron is the basic structural and functional unit of the kidney. It filters blood, reabsorbs essential substances, and secretes waste products to form urine.

45. Which substance is passively reabsorbed in the proximal tubule?

  • a) Glucose
  • b) Sodium
  • c) Urea
  • d) Potassium

Answer: c) Urea
Explanation: Urea is passively reabsorbed in the proximal tubule due to the osmotic gradient created by water reabsorption. However, a significant portion is excreted in the urine.

46. How does the kidney regulate erythropoiesis?

  • a) By secreting renin
  • b) By excreting potassium
  • c) By producing erythropoietin
  • d) By filtering blood

Answer: c) By producing erythropoietin
Explanation: The kidney produces erythropoietin in response to low oxygen levels in the blood. Erythropoietin stimulates the bone marrow to produce more red blood cells, increasing oxygen transport.

47. What is the primary driving force for glomerular filtration?

  • a) Osmotic pressure
  • b) Hydrostatic pressure
  • c) Oncotic pressure
  • d) Active transport

Answer: b) Hydrostatic pressure
Explanation: Glomerular filtration is driven by the hydrostatic pressure of blood in the glomerular capillaries, which forces plasma and small solutes through the filtration membrane.

48. Which hormone is responsible for sodium reabsorption in the distal convoluted tubule?

  • a) ADH
  • b) Cortisol
  • c) Aldosterone
  • d) Insulin

Answer: c) Aldosterone
Explanation: Aldosterone promotes sodium reabsorption in the distal convoluted tubule and collecting ducts, which helps maintain blood volume and blood pressure by conserving sodium.

49. What is the renal countercurrent mechanism?

  • a) A mechanism for glucose absorption
  • b) A system for concentrating urine
  • c) A pathway for erythropoietin release
  • d) A blood pressure regulation system

Answer: b) A system for concentrating urine
Explanation: The countercurrent mechanism in the loop of Henle establishes a medullary concentration gradient that allows the kidneys to produce concentrated urine by reabsorbing water from the collecting ducts.

50. What triggers the release of renin from the kidneys?

Answer: b) Low blood pressure
Explanation: Renin is released by the juxtaglomerular cells of the kidney in response to low blood pressure, decreased sodium levels, or sympathetic nervous system activation. Renin plays a key role in the RAAS system to restore blood pressure.

51. What is the function of the macula densa in the kidney?

  • a) Secrete aldosterone
  • b) Detect sodium concentration in filtrate
  • c) Produce renin
  • d) Regulate potassium reabsorption

Answer: b) Detect sodium concentration in filtrate
Explanation: The macula densa, located in the distal convoluted tubule, senses sodium chloride levels in the filtrate. If sodium levels are low, it signals the juxtaglomerular cells to release renin, activating the RAAS system.

52. What is the normal glomerular filtration rate (GFR) in healthy adults?

  • a) 30 mL/min
  • b) 90-120 mL/min
  • c) 150-200 mL/min
  • d) 60 mL/min

Answer: b) 90-120 mL/min
Explanation: The normal GFR in healthy adults is 90 to 120 mL/min. It reflects the amount of blood filtered by the glomeruli each minute and is a key indicator of kidney function.

53. Which segment of the nephron is impermeable to water?

  • a) Proximal convoluted tubule
  • b) Descending limb of the loop of Henle
  • c) Ascending limb of the loop of Henle
  • d) Collecting duct

Answer: c) Ascending limb of the loop of Henle
Explanation: The ascending limb of the loop of Henle is impermeable to water but actively transports sodium and chloride out of the tubule, contributing to the countercurrent mechanism.

54. What is the primary role of the proximal convoluted tubule?

  • a) Excrete urea
  • b) Reabsorb glucose, amino acids, and electrolytes
  • c) Produce erythropoietin
  • d) Secrete aldosterone

Answer: b) Reabsorb glucose, amino acids, and electrolytes
Explanation: The proximal convoluted tubule reabsorbs about 65-70% of the filtered water and solutes, including glucose, amino acids, sodium, and chloride, from the glomerular filtrate.

55. What does a high blood urea nitrogen (BUN) level indicate?

  • a) Normal kidney function
  • b) Hypokalemia
  • c) Impaired kidney function
  • d) Low blood glucose

Answer: c) Impaired kidney function
Explanation: High BUN levels suggest impaired kidney function or dehydration. BUN is a waste product of protein metabolism that the kidneys excrete; when kidney function is compromised, BUN accumulates in the blood.

56. Which hormone increases calcium reabsorption in the kidney?

  • a) Parathyroid hormone (PTH)
  • b) Aldosterone
  • c) Insulin
  • d) ADH

Answer: a) Parathyroid hormone (PTH)
Explanation: PTH promotes calcium reabsorption in the distal convoluted tubules of the kidney and reduces phosphate reabsorption, helping to maintain calcium homeostasis.

57. What does the renal clearance of a substance measure?

  • a) Blood pressure regulation
  • b) The ability of the kidney to secrete hormones
  • c) The volume of plasma cleared of a substance per unit time
  • d) Glucose absorption efficiency

Answer: c) The volume of plasma cleared of a substance per unit time
Explanation: Renal clearance measures the efficiency of the kidney in removing a specific substance from plasma. It is often used to assess kidney function and GFR.

58. What role does angiotensin II play in the kidneys?

  • a) Increases glomerular filtration
  • b) Causes vasodilation
  • c) Stimulates aldosterone release and vasoconstriction
  • d) Promotes potassium excretion

Answer: c) Stimulates aldosterone release and vasoconstriction
Explanation: Angiotensin II causes vasoconstriction and stimulates aldosterone release, leading to sodium and water retention, which helps increase blood pressure and restore fluid balance.

59. What is a key function of the distal convoluted tubule?

  • a) Glucose reabsorption
  • b) Secretion of potassium and hydrogen ions
  • c) Filtration of plasma
  • d) Urea reabsorption

Answer: b) Secretion of potassium and hydrogen ions
Explanation: The distal convoluted tubule plays a role in the fine-tuning of electrolyte balance by secreting potassium and hydrogen ions and reabsorbing sodium under the influence of aldosterone.

60. What condition is characterized by the presence of protein in the urine?

  • a) Glycosuria
  • b) Hematuria
  • c) Proteinuria
  • d) Pyuria

Answer: c) Proteinuria
Explanation: Proteinuria occurs when protein is present in the urine, indicating possible damage to the glomerular filtration barrier, which may be caused by kidney disease, hypertension, or diabetes.

61. What does the term "renal threshold" refer to?

  • a) The concentration at which glucose appears in the urine
  • b) The minimum amount of urine produced daily
  • c) The concentration of sodium required for filtration
  • d) The maximum capacity of the kidney to filter waste

Answer: a) The concentration at which glucose appears in the urine
Explanation: The renal threshold refers to the blood concentration of a substance (e.g., glucose) at which it begins to appear in the urine due to the renal tubules’ inability to reabsorb it fully.

62. What is the effect of acidosis on renal function?

  • a) Increases bicarbonate secretion
  • b) Decreases hydrogen ion secretion
  • c) Increases sodium reabsorption
  • d) Decreases calcium reabsorption

Answer: a) Increases bicarbonate secretion
Explanation: In acidosis, the kidneys compensate by secreting hydrogen ions into the urine and reabsorbing bicarbonate to buffer the excess acid and restore normal pH levels.

63. Which nephron structure is responsible for the filtration of blood?

  • a) Bowman's capsule
  • b) Loop of Henle
  • c) Proximal convoluted tubule
  • d) Collecting duct

Answer: a) Bowman's capsule
Explanation: The Bowman's capsule surrounds the glomerulus and is responsible for the filtration of blood. It is the first step in the formation of urine, where blood plasma is filtered into the renal tubules.

64. How does aldosterone affect potassium levels in the body?

  • a) Increases potassium reabsorption
  • b) Decreases potassium secretion
  • c) Increases potassium excretion
  • d) Decreases potassium levels

Answer: c) Increases potassium excretion
Explanation: Aldosterone increases the excretion of potassium in the urine by enhancing the activity of sodium-potassium pumps in the distal convoluted tubule and collecting ducts, thus maintaining electrolyte balance.

65. What effect does dehydration have on the kidneys?

  • a) Increases urine volume
  • b) Decreases ADH secretion
  • c) Increases sodium excretion
  • d) Increases water reabsorption

Answer: d) Increases water reabsorption
Explanation: During dehydration, the kidneys conserve water by increasing ADH secretion, which enhances water reabsorption in the collecting ducts, resulting in concentrated urine and minimal water loss.

66. What is the role of the juxtaglomerular apparatus in the kidney?

  • a) Regulates renal blood flow and glomerular filtration rate
  • b) Secretes hormones to control urine output
  • c) Initiates the filtration process in the Bowman's capsule
  • d) Reabsorbs sodium and chloride in the loop of Henle

Answer: a) Regulates renal blood flow and glomerular filtration rate
Explanation: The juxtaglomerular apparatus, located near the afferent arteriole, plays a key role in regulating renal blood flow and GFR by releasing renin in response to low blood pressure or low sodium levels.

67. Which molecule is the primary energy source for renal tubular cells?

  • a) Glucose
  • b) Lactate
  • c) Fatty acids
  • d) Amino acids

Answer: a) Glucose
Explanation: Renal tubular cells primarily use glucose as their energy source for active transport processes, such as the reabsorption of sodium and glucose from the filtrate back into the blood.

68. What is the role of urodilatin in the kidneys?

  • a) Increases sodium reabsorption
  • b) Increases water reabsorption
  • c) Decreases sodium reabsorption
  • d) Dilates renal blood vessels

Answer: c) Decreases sodium reabsorption
Explanation: Urodilatin, a hormone secreted by the kidney, helps regulate sodium and water balance by inhibiting sodium reabsorption in the distal nephron and promoting natriuresis (excretion of sodium in urine).

69. What is the function of the vasa recta in the kidney?

  • a) Transport urine to the renal pelvis
  • b) Maintain the medullary osmotic gradient
  • c) Secrete erythropoietin
  • d) Filter plasma

Answer: b) Maintain the medullary osmotic gradient
Explanation: The vasa recta is a network of capillaries that runs parallel to the loop of Henle. It plays a crucial role in maintaining the osmotic gradient in the renal medulla, aiding in water and solute reabsorption.

70. How do the kidneys respond to increased blood pressure?

  • a) Increase renin secretion
  • b) Decrease sodium excretion
  • c) Increase glomerular filtration rate (GFR)
  • d) Increase urine output

Answer: d) Increase urine output
Explanation: In response to increased blood pressure, the kidneys excrete more sodium and water to reduce blood volume, thus helping to bring blood pressure back to normal.

71. What is the effect of parathyroid hormone (PTH) on phosphate levels?

  • a) Increases phosphate reabsorption
  • b) Decreases phosphate reabsorption
  • c) Increases phosphate secretion
  • d) Decreases phosphate excretion

Answer: b) Decreases phosphate reabsorption
Explanation: PTH reduces phosphate reabsorption in the kidneys, leading to increased phosphate excretion in the urine. This helps to balance calcium and phosphate levels in the body.

72. What is the role of nitric oxide (NO) in renal function?

  • a) Promotes renal vasoconstriction
  • b) Inhibits sodium reabsorption
  • c) Promotes renal vasodilation
  • d) Increases glomerular filtration rate

Answer: c) Promotes renal vasodilation
Explanation: Nitric oxide acts as a vasodilator in the kidneys, helping to increase renal blood flow and glomerular filtration rate, which enhances the kidney’s ability to filter blood.

73. What is the effect of increased sympathetic nervous system activity on renal function?

  • a) Increases renal blood flow
  • b) Decreases sodium excretion
  • c) Increases urine volume
  • d) Increases filtration rate

Answer: b) Decreases sodium excretion
Explanation: Increased sympathetic activity causes vasoconstriction of renal vessels, reducing renal blood flow and glomerular filtration rate, and ultimately decreasing sodium excretion.

74. What is the primary function of the renal pelvis?

  • a) Filtration of blood
  • b) Collection of urine
  • c) Reabsorption of water
  • d) Secretion of hormones

Answer: b) Collection of urine
Explanation: The renal pelvis is a funnel-shaped structure that collects urine from the renal calyces and channels it into the ureter for transport to the bladder.

75. Which structure in the nephron is responsible for most of the reabsorption of sodium?

  • a) Proximal convoluted tubule
  • b) Distal convoluted tubule
  • c) Loop of Henle
  • d) Collecting duct

Answer: a) Proximal convoluted tubule
Explanation: The proximal convoluted tubule is responsible for reabsorbing approximately 65% of the sodium filtered by the glomerulus, as well as other vital solutes and water.

76. What is the effect of atrial natriuretic peptide (ANP) on kidney function?

  • a) Increases sodium reabsorption
  • b) Increases potassium secretion
  • c) Decreases sodium reabsorption
  • d) Stimulates renin release

Answer: c) Decreases sodium reabsorption
Explanation: Atrial natriuretic peptide (ANP) promotes the excretion of sodium by decreasing sodium reabsorption in the distal tubules and collecting ducts, which leads to increased urine output and helps reduce blood volume and pressure.

77. Which cells in the kidney are responsible for the production of renin?

  • a) Macula densa cells
  • b) Juxtaglomerular cells
  • c) Proximal convoluted tubule cells
  • d) Collecting duct cells

Answer: b) Juxtaglomerular cells
Explanation: Juxtaglomerular cells, located in the afferent arteriole of the kidney, produce and secrete renin in response to low blood pressure or sodium levels, activating the renin-angiotensin-aldosterone system (RAAS).

78. What is the primary action of antidiuretic hormone (ADH)?

  • a) Increase sodium reabsorption
  • b) Increase potassium secretion
  • c) Increase water reabsorption
  • d) Decrease glomerular filtration rate

Answer: c) Increase water reabsorption
Explanation: ADH increases water reabsorption in the collecting ducts of the kidneys by promoting the insertion of aquaporin channels, thereby reducing urine output and conserving water in response to dehydration or high blood osmolarity.

79. How does the kidney regulate acid-base balance?

  • a) By excreting bicarbonate and reabsorbing hydrogen ions
  • b) By producing glucose
  • c) By regulating calcium and phosphate levels
  • d) By producing erythropoietin

Answer: a) By excreting bicarbonate and reabsorbing hydrogen ions
Explanation: The kidneys help maintain acid-base balance by reabsorbing bicarbonate from the urine and secreting hydrogen ions into the urine, which helps regulate the blood pH.

80. What is the role of the loop of Henle in urine concentration?

  • a) Filtration of blood
  • b) Reabsorption of glucose
  • c) Creation of a medullary osmotic gradient for water reabsorption
  • d) Excretion of urea

Answer: c) Creation of a medullary osmotic gradient for water reabsorption
Explanation: The loop of Henle creates an osmotic gradient in the renal medulla, allowing the kidneys to reabsorb water from the filtrate and concentrate urine, thus conserving water in the body.

81. What is the role of erythropoietin in the kidneys?

  • a) Stimulates red blood cell production in the bone marrow
  • b) Regulates sodium balance
  • c) Enhances glucose reabsorption
  • d) Stimulates aldosterone release

Answer: a) Stimulates red blood cell production in the bone marrow
Explanation: Erythropoietin is a hormone produced by the kidneys in response to hypoxia. It stimulates the bone marrow to produce red blood cells, thereby increasing the oxygen-carrying capacity of the blood.

82. What is the effect of hyperkalemia on kidney function?

  • a) Increased sodium excretion
  • b) Increased potassium excretion
  • c) Decreased potassium excretion
  • d) Increased glomerular filtration rate

Answer: b) Increased potassium excretion
Explanation: Hyperkalemia triggers the release of aldosterone, which increases the excretion of potassium in the urine to restore normal potassium levels and maintain electrolyte balance.

83. What is the role of the kidney in vitamin D metabolism?

  • a) Activation of vitamin D to its active form
  • b) Production of vitamin D
  • c) Inactivation of vitamin D
  • d) Storage of vitamin D

Answer: a) Activation of vitamin D to its active form
Explanation: The kidneys convert vitamin D into its active form, calcitriol, which enhances calcium absorption from the intestines and helps regulate calcium and phosphate levels in the blood.

84. What is the effect of a decreased glomerular filtration rate (GFR) on renal function?

  • a) Increased urine output
  • b) Decreased waste product clearance
  • c) Increased sodium reabsorption
  • d) Increased renal blood flow

Answer: b) Decreased waste product clearance
Explanation: A decreased GFR indicates impaired kidney function, leading to reduced clearance of waste products such as urea and creatinine, which can accumulate in the blood and indicate kidney dysfunction.

85. What is the effect of aldosterone on the kidneys?

  • a) Promotes water excretion
  • b) Stimulates sodium and water reabsorption
  • c) Inhibits potassium excretion
  • d) Stimulates urea production

Answer: b) Stimulates sodium and water reabsorption
Explanation: Aldosterone acts on the distal convoluted tubules and collecting ducts to increase sodium reabsorption, which in turn promotes water reabsorption, helping to maintain blood volume and pressure.

86. How does the kidney respond to alkalosis?

  • a) By excreting bicarbonate and retaining hydrogen ions
  • b) By increasing water reabsorption
  • c) By secreting aldosterone
  • d) By reducing sodium reabsorption

Answer: a) By excreting bicarbonate and retaining hydrogen ions
Explanation: In alkalosis, the kidneys compensate by excreting bicarbonate into the urine and retaining hydrogen ions to lower the blood pH back to normal levels.

87. What is the main role of the afferent arteriole in the kidney?

  • a) Filtration of blood
  • b) Regulation of glomerular filtration rate
  • c) Transport of urine
  • d) Secretion of renin

Answer: b) Regulation of glomerular filtration rate
Explanation: The afferent arteriole controls blood flow into the glomerulus and thus regulates the glomerular filtration rate (GFR). Vasoconstriction or vasodilation of the afferent arteriole helps adjust GFR according to body needs.

88. What is the main function of the renal corpuscle?

  • a) Reabsorption of nutrients
  • b) Filtration of blood
  • c) Secretion of waste products
  • d) Regulation of electrolyte balance

Answer: b) Filtration of blood
Explanation: The renal corpuscle consists of the glomerulus and Bowman's capsule. It is responsible for the filtration of blood, allowing water and solutes to pass into the nephron, forming the initial filtrate.

89. What is the function of the collecting ducts in the kidney?

  • a) Secretion of hydrogen ions
  • b) Reabsorption of sodium and water
  • c) Filtration of blood plasma
  • d) Secretion of erythropoietin

Answer: b) Reabsorption of sodium and water
Explanation: The collecting ducts play a key role in reabsorbing sodium and water, under the influence of hormones like aldosterone and ADH, helping to regulate urine volume and concentration.

90. Which of the following is a function of the kidneys?

  • a) Glucose production
  • b) Protein synthesis
  • c) Waste excretion
  • d) Oxygen transport

Answer: c) Waste excretion
Explanation: The kidneys excrete metabolic waste products, such as urea, creatinine, and uric acid, which are filtered from the blood and excreted in urine, helping maintain homeostasis in the body.

91. What is the role of the proximal convoluted tubule in renal function?

  • a) Filtration of blood
  • b) Reabsorption of water, sodium, glucose, and amino acids
  • c) Secretion of potassium and hydrogen ions
  • d) Filtration of urea

Answer: b) Reabsorption of water, sodium, glucose, and amino acids
Explanation: The proximal convoluted tubule is the site where a significant amount of reabsorption occurs, including water, sodium, glucose, and amino acids, from the filtrate back into the bloodstream.


92. What does the term "renal clearance" refer to?

  • a) The filtration of blood by the kidneys
  • b) The excretion of waste products in urine
  • c) The ability of the kidneys to remove a substance from the blood
  • d) The reabsorption of water and solutes

Answer: c) The ability of the kidneys to remove a substance from the blood
Explanation: Renal clearance refers to the volume of plasma from which a substance is completely removed by the kidneys per unit of time. It is used to assess kidney function and the elimination of drugs or waste products.

93. Which part of the nephron is primarily involved in the regulation of blood pressure?

  • a) Proximal convoluted tubule
  • b) Distal convoluted tubule
  • c) Juxtaglomerular apparatus
  • d) Collecting ducts

Answer: c) Juxtaglomerular apparatus
Explanation: The juxtaglomerular apparatus, located at the junction of the distal convoluted tubule and afferent arteriole, plays a key role in regulating blood pressure by releasing renin in response to changes in blood flow or sodium concentration.

94. Which of the following is primarily responsible for the reabsorption of sodium in the nephron?

  • a) Proximal convoluted tubule
  • b) Loop of Henle
  • c) Distal convoluted tubule
  • d) Collecting ducts

Answer: a) Proximal convoluted tubule
Explanation: The proximal convoluted tubule is responsible for the reabsorption of approximately 65-70% of sodium from the filtrate. This process is essential for maintaining sodium and fluid balance.

95. How do the kidneys maintain fluid and electrolyte balance?

  • a) By reabsorbing water and solutes as needed
  • b) By producing glucose
  • c) By excreting all electrolytes
  • d) By maintaining a constant glomerular filtration rate

Answer: a) By reabsorbing water and solutes as needed
Explanation: The kidneys regulate fluid and electrolyte balance by selectively reabsorbing water and solutes, such as sodium and potassium, based on the body's needs. This process helps maintain homeostasis.

96. What does the term "glomerular filtration rate (GFR)" measure?

  • a) The amount of blood filtered by the kidneys per minute
  • b) The total volume of urine produced
  • c) The concentration of waste products in the blood
  • d) The amount of sodium excreted in the urine

Answer: a) The amount of blood filtered by the kidneys per minute
Explanation: GFR measures the volume of blood filtered by the glomeruli per minute and is a key indicator of kidney function. A decrease in GFR can suggest impaired renal function.

97. What is the primary function of the distal convoluted tubule?

  • a) Reabsorption of glucose
  • b) Filtration of plasma
  • c) Regulation of calcium and sodium reabsorption
  • d) Secretion of creatinine

Answer: c) Regulation of calcium and sodium reabsorption
Explanation: The distal convoluted tubule fine-tunes the reabsorption of sodium, calcium, and other electrolytes, under the influence of hormones like aldosterone and parathyroid hormone (PTH).

98. What is the main function of the vasa recta in the kidneys?

  • a) Secretion of renin
  • b) Transport of glucose
  • c) Maintaining the osmotic gradient in the renal medulla
  • d) Filtration of blood

Answer: c) Maintaining the osmotic gradient in the renal medulla
Explanation: The vasa recta is a network of capillaries that surrounds the loop of Henle and plays a crucial role in maintaining the osmotic gradient in the renal medulla, aiding in the concentration of urine.

99. What is the effect of hypokalemia on kidney function?

  • a) Increased potassium reabsorption
  • b) Decreased potassium excretion
  • c) Increased potassium excretion
  • d) Decreased sodium reabsorption

Answer: c) Increased potassium excretion
Explanation: Hypokalemia leads to an increase in potassium excretion as the kidneys try to restore potassium balance, which can result in an increased risk of dehydration and electrolyte imbalances.

100. What is the effect of renin on the kidneys?

  • a) Decreases blood pressure
  • b) Increases sodium reabsorption
  • c) Decreases potassium excretion
  • d) Reduces urine production

Answer: b) Increases sodium reabsorption
Explanation: Renin is released by the kidneys in response to low blood pressure. It activates the renin-angiotensin-aldosterone system (RAAS), leading to the secretion of aldosterone, which increases sodium reabsorption in the kidneys and raises blood pressure.

 

How useful was this post?

Click on a star to rate it!

Average rating 4.8 / 5. Vote count: 5682

No votes so far! Be the first to rate this post.

You Can Share MedicoInfo through :

Leave a Reply

Your email address will not be published. Required fields are marked *