PATHOPHYSIOLOGY MODULE 8 EXAM PRACTICE |
RENAL SYSTEM & ACID-BASE BALANCE |
COMPREHENSIVE 2026/2027 UPDATE EXAM
QUESTIONS 100% WITH CORRECT ANSWERS AND
RATIOALES
Which structure of the nephron is primarily responsible for the initial filtration
of blood?
A. Loop of Henle
B. Collecting duct
C. Glomerulus and Bowman's capsule
D. Distal convoluted tubule
Rationale: The glomerulus is a network of capillaries that filters plasma from
the blood into Bowman's capsule, producing the filtrate that enters the nephron.
This filtration is driven primarily by hydrostatic pressure within the glomerular
capillaries. The filtrate normally contains water and small dissolved substances but
excludes most blood cells and large plasma proteins. The filtrate then passes
through the proximal tubule, loop of Henle, distal tubule, and collecting duct,
where reabsorption and secretion modify its composition.
Which hormone increases water reabsorption in the collecting ducts of the
kidneys?
A. Aldosterone
B. Antidiuretic hormone (ADH)
C. Atrial natriuretic peptide
D. Renin
Page 1 of 78
, Rationale: ADH, also called vasopressin, increases the permeability of the
collecting ducts to water by promoting insertion of aquaporin-2 water channels
into the tubular membrane. This allows more water to move from the tubular
fluid back into the bloodstream, producing a smaller volume of more
concentrated urine. ADH release increases when plasma osmolality rises or when
blood volume or pressure falls significantly.
A patient has a serum creatinine concentration that is significantly elevated
above the normal range. What does this finding most strongly suggest?
A. Increased renal filtration
B. Excessive glucose reabsorption
C. Increased erythropoietin production
D. Reduced glomerular filtration rate
Rationale: Creatinine is a waste product generated largely from skeletal
muscle metabolism and is normally filtered by the kidneys. When glomerular
filtration decreases, creatinine accumulates in the bloodstream. Therefore, an
elevated serum creatinine level can indicate impaired kidney function, particularly
when interpreted alongside estimated GFR and the patient's clinical condition.
Creatinine should not be interpreted in isolation because muscle mass, diet,
medications, and other factors can influence its concentration.
Which substance is normally reabsorbed almost completely in the proximal
convoluted tubule under normal physiological conditions?
A. Glucose
B. Creatinine
C. Urea
D. Hydrogen ions
Rationale: Filtered glucose is normally reabsorbed almost completely in the
proximal convoluted tubule through sodium-glucose cotransport mechanisms.
Page 2 of 78
,Consequently, little or no glucose should normally appear in the urine. When
blood glucose exceeds the renal threshold and the transporters become
saturated, glucose begins to appear in the urine, producing glucosuria. This is
commonly associated with uncontrolled diabetes mellitus.
What is the primary function of aldosterone in the distal nephron?
A. Increase calcium excretion
B. Decrease sodium reabsorption
C. Increase sodium reabsorption and potassium secretion
D. Prevent hydrogen ion secretion
Rationale: Aldosterone acts primarily on principal cells in the late distal tubule
and collecting duct. It promotes sodium reabsorption, which contributes to water
retention and maintenance of extracellular fluid volume, while increasing
potassium secretion into the tubular fluid. Aldosterone also influences hydrogen
ion handling indirectly through its effects on renal tubular cells. Excess
aldosterone can contribute to hypertension and hypokalemia, whereas
inadequate aldosterone activity can contribute to sodium loss, hyperkalemia, and
hypotension.
Which finding is most characteristic of nephrotic syndrome?
A. Severe proteinuria
B. Respiratory alkalosis
C. Low urine output caused exclusively by dehydration
D. Increased red blood cell production
Rationale: Nephrotic syndrome is characterized by substantial protein loss
through the urine due to increased glomerular permeability. Major features
include heavy proteinuria, hypoalbuminemia, edema, and often hyperlipidemia.
Loss of albumin reduces plasma oncotic pressure, promoting movement of fluid
Page 3 of 78
, into the interstitial tissues. The resulting edema can be generalized and may
become particularly noticeable in dependent areas.
Which acid-base disturbance is most likely when a patient has a primary
decrease in serum bicarbonate?
A. Respiratory alkalosis
B. Metabolic acidosis
C. Respiratory acidosis
D. Metabolic alkalosis
Rationale: Bicarbonate is the major extracellular base and an important
component of the body's primary buffering system. A primary reduction in serum
bicarbonate is characteristic of metabolic acidosis. Causes include increased acid
production, impaired renal acid excretion, bicarbonate loss, and certain toxin
exposures. The respiratory system usually compensates by increasing ventilation,
which lowers carbon dioxide and helps raise the pH toward normal.
A patient with prolonged vomiting is at increased risk of which acid-base
disturbance?
A. Metabolic alkalosis
B. Metabolic acidosis
C. Respiratory acidosis
D. Respiratory alkalosis
Rationale: Prolonged vomiting causes loss of gastric hydrochloric acid,
resulting in loss of hydrogen and chloride ions. This can produce metabolic
alkalosis, particularly when vomiting is severe or persistent. Volume depletion can
further maintain the alkalosis by activating the renin-angiotensin-aldosterone
system, which promotes renal sodium retention and potassium and hydrogen ion
secretion. Patients may also develop hypokalemia and chloride depletion.
Page 4 of 78
RENAL SYSTEM & ACID-BASE BALANCE |
COMPREHENSIVE 2026/2027 UPDATE EXAM
QUESTIONS 100% WITH CORRECT ANSWERS AND
RATIOALES
Which structure of the nephron is primarily responsible for the initial filtration
of blood?
A. Loop of Henle
B. Collecting duct
C. Glomerulus and Bowman's capsule
D. Distal convoluted tubule
Rationale: The glomerulus is a network of capillaries that filters plasma from
the blood into Bowman's capsule, producing the filtrate that enters the nephron.
This filtration is driven primarily by hydrostatic pressure within the glomerular
capillaries. The filtrate normally contains water and small dissolved substances but
excludes most blood cells and large plasma proteins. The filtrate then passes
through the proximal tubule, loop of Henle, distal tubule, and collecting duct,
where reabsorption and secretion modify its composition.
Which hormone increases water reabsorption in the collecting ducts of the
kidneys?
A. Aldosterone
B. Antidiuretic hormone (ADH)
C. Atrial natriuretic peptide
D. Renin
Page 1 of 78
, Rationale: ADH, also called vasopressin, increases the permeability of the
collecting ducts to water by promoting insertion of aquaporin-2 water channels
into the tubular membrane. This allows more water to move from the tubular
fluid back into the bloodstream, producing a smaller volume of more
concentrated urine. ADH release increases when plasma osmolality rises or when
blood volume or pressure falls significantly.
A patient has a serum creatinine concentration that is significantly elevated
above the normal range. What does this finding most strongly suggest?
A. Increased renal filtration
B. Excessive glucose reabsorption
C. Increased erythropoietin production
D. Reduced glomerular filtration rate
Rationale: Creatinine is a waste product generated largely from skeletal
muscle metabolism and is normally filtered by the kidneys. When glomerular
filtration decreases, creatinine accumulates in the bloodstream. Therefore, an
elevated serum creatinine level can indicate impaired kidney function, particularly
when interpreted alongside estimated GFR and the patient's clinical condition.
Creatinine should not be interpreted in isolation because muscle mass, diet,
medications, and other factors can influence its concentration.
Which substance is normally reabsorbed almost completely in the proximal
convoluted tubule under normal physiological conditions?
A. Glucose
B. Creatinine
C. Urea
D. Hydrogen ions
Rationale: Filtered glucose is normally reabsorbed almost completely in the
proximal convoluted tubule through sodium-glucose cotransport mechanisms.
Page 2 of 78
,Consequently, little or no glucose should normally appear in the urine. When
blood glucose exceeds the renal threshold and the transporters become
saturated, glucose begins to appear in the urine, producing glucosuria. This is
commonly associated with uncontrolled diabetes mellitus.
What is the primary function of aldosterone in the distal nephron?
A. Increase calcium excretion
B. Decrease sodium reabsorption
C. Increase sodium reabsorption and potassium secretion
D. Prevent hydrogen ion secretion
Rationale: Aldosterone acts primarily on principal cells in the late distal tubule
and collecting duct. It promotes sodium reabsorption, which contributes to water
retention and maintenance of extracellular fluid volume, while increasing
potassium secretion into the tubular fluid. Aldosterone also influences hydrogen
ion handling indirectly through its effects on renal tubular cells. Excess
aldosterone can contribute to hypertension and hypokalemia, whereas
inadequate aldosterone activity can contribute to sodium loss, hyperkalemia, and
hypotension.
Which finding is most characteristic of nephrotic syndrome?
A. Severe proteinuria
B. Respiratory alkalosis
C. Low urine output caused exclusively by dehydration
D. Increased red blood cell production
Rationale: Nephrotic syndrome is characterized by substantial protein loss
through the urine due to increased glomerular permeability. Major features
include heavy proteinuria, hypoalbuminemia, edema, and often hyperlipidemia.
Loss of albumin reduces plasma oncotic pressure, promoting movement of fluid
Page 3 of 78
, into the interstitial tissues. The resulting edema can be generalized and may
become particularly noticeable in dependent areas.
Which acid-base disturbance is most likely when a patient has a primary
decrease in serum bicarbonate?
A. Respiratory alkalosis
B. Metabolic acidosis
C. Respiratory acidosis
D. Metabolic alkalosis
Rationale: Bicarbonate is the major extracellular base and an important
component of the body's primary buffering system. A primary reduction in serum
bicarbonate is characteristic of metabolic acidosis. Causes include increased acid
production, impaired renal acid excretion, bicarbonate loss, and certain toxin
exposures. The respiratory system usually compensates by increasing ventilation,
which lowers carbon dioxide and helps raise the pH toward normal.
A patient with prolonged vomiting is at increased risk of which acid-base
disturbance?
A. Metabolic alkalosis
B. Metabolic acidosis
C. Respiratory acidosis
D. Respiratory alkalosis
Rationale: Prolonged vomiting causes loss of gastric hydrochloric acid,
resulting in loss of hydrogen and chloride ions. This can produce metabolic
alkalosis, particularly when vomiting is severe or persistent. Volume depletion can
further maintain the alkalosis by activating the renin-angiotensin-aldosterone
system, which promotes renal sodium retention and potassium and hydrogen ion
secretion. Patients may also develop hypokalemia and chloride depletion.
Page 4 of 78
