PATHOPHYSIOLOGY MODULE 8 EXAM PRACTICE |
RENAL SYSTEM & ACID-BASE BALANCE |
COMPREHENSIVE 2026/2027 UPDATE EXAM
QUESTIONS 100% WITH CORRECT ANSWERS AND
RATIOALES
Which structure is considered the functional unit of the kidney?
A. Renal pelvis
B. Nephron
C. Ureter
D. Glomerulus
Correct Answer: B. Nephron
Rationale: The nephron is the functional unit of the kidney because it
performs the major processes required to form urine, including filtration,
reabsorption, and secretion. Each kidney contains a very large number of
nephrons, allowing the kidneys to continuously regulate fluid volume, electrolytes,
waste products, and acid–base status.
What is the primary function of the glomerulus?
A. Reabsorption of sodium
B. Secretion of hydrogen ions
C. Filtration of blood plasma
D. Concentration of urine
Correct Answer: C. Filtration of blood plasma
Rationale: The glomerulus is a network of specialized capillaries where blood
is filtered under pressure. Water and small dissolved substances can pass into
Bowman's capsule, while most blood cells and large plasma proteins remain
within the circulation. This initial filtrate subsequently undergoes extensive
modification along the renal tubule.
Page 1 of 51
,Which hormone increases water reabsorption in the collecting ducts?
A. Insulin
B. Antidiuretic hormone
C. Thyroxine
D. Parathyroid hormone
Correct Answer: B. Antidiuretic hormone
Rationale: Antidiuretic hormone (ADH), also called vasopressin, increases the
permeability of the collecting ducts to water. This allows more water to move
from the tubular fluid back into the bloodstream, producing a smaller volume of
more concentrated urine. ADH therefore plays an important role in maintaining
body-fluid osmolality and volume.
Which part of the nephron is primarily responsible for the greatest amount of
filtered sodium and water reabsorption?
A. Proximal convoluted tubule
B. Distal convoluted tubule
C. Collecting duct
D. Renal pelvis
Correct Answer: A. Proximal convoluted tubule
Rationale: The proximal convoluted tubule reabsorbs a large proportion of the
filtered sodium and water, as well as substantial amounts of glucose, amino acids,
bicarbonate, and other substances. Its extensive reabsorptive capacity is essential
because the kidneys filter a very large volume of plasma each day and cannot
allow all filtered water and useful solutes to be lost in urine.
Which substance is normally prevented from passing through the glomerular
filtration barrier in significant amounts?
A. Sodium
B. Water
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,C. Glucose
D. Large plasma proteins
Correct Answer: D. Large plasma proteins
Rationale: The glomerular filtration barrier restricts the passage of cells and
most large plasma proteins. Small molecules such as water, electrolytes, glucose,
and urea can normally enter the filtrate. Significant protein loss in urine, or
proteinuria, can indicate damage to the glomerular filtration barrier.
What is the main nitrogenous waste product excreted by the kidneys?
A. Urea
B. Oxygen
C. Albumin
D. Glycogen
Correct Answer: A. Urea
Rationale: Urea is produced primarily by the liver as a result of protein
metabolism and is subsequently transported in the blood to the kidneys for
excretion. Blood urea nitrogen can be used as one indicator of renal function,
although it is influenced by factors such as hydration, protein intake, and
gastrointestinal bleeding.
Which renal process moves substances from the blood into the renal tubular
fluid after filtration?
A. Reabsorption
B. Secretion
C. Osmosis
D. Filtration
Correct Answer: B. Secretion
Rationale: Tubular secretion involves the movement of substances from
peritubular blood into the renal tubular fluid. Hydrogen ions, potassium under
certain circumstances, creatinine, and various medications can be secreted into
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, the tubular system. Secretion helps the kidneys eliminate substances that may not
have been adequately removed during glomerular filtration.
Which renal process returns useful substances from tubular fluid to the
bloodstream?
A. Filtration
B. Secretion
C. Reabsorption
D. Excretion
Correct Answer: C. Reabsorption
Rationale: Reabsorption returns water and useful solutes from the tubular
fluid into the circulation. Depending on the substance and nephron segment,
reabsorption may occur through passive or active mechanisms. This process
prevents valuable substances such as glucose, sodium, and water from being
unnecessarily lost in urine.
Which electrolyte is particularly important in determining resting membrane
potential and cardiac electrical activity?
A. Potassium
B. Chloride
C. Phosphate
D. Bicarbonate
Correct Answer: A. Potassium
Rationale: Potassium is the major intracellular cation and has a major
influence on the electrical gradient across cell membranes. Abnormal potassium
concentrations can therefore affect skeletal muscle, smooth muscle, and
especially cardiac conduction. The kidneys are central to potassium balance
because they regulate potassium excretion according to the body's needs.
What is the normal primary role of aldosterone in the kidney?
Page 4 of 51
RENAL SYSTEM & ACID-BASE BALANCE |
COMPREHENSIVE 2026/2027 UPDATE EXAM
QUESTIONS 100% WITH CORRECT ANSWERS AND
RATIOALES
Which structure is considered the functional unit of the kidney?
A. Renal pelvis
B. Nephron
C. Ureter
D. Glomerulus
Correct Answer: B. Nephron
Rationale: The nephron is the functional unit of the kidney because it
performs the major processes required to form urine, including filtration,
reabsorption, and secretion. Each kidney contains a very large number of
nephrons, allowing the kidneys to continuously regulate fluid volume, electrolytes,
waste products, and acid–base status.
What is the primary function of the glomerulus?
A. Reabsorption of sodium
B. Secretion of hydrogen ions
C. Filtration of blood plasma
D. Concentration of urine
Correct Answer: C. Filtration of blood plasma
Rationale: The glomerulus is a network of specialized capillaries where blood
is filtered under pressure. Water and small dissolved substances can pass into
Bowman's capsule, while most blood cells and large plasma proteins remain
within the circulation. This initial filtrate subsequently undergoes extensive
modification along the renal tubule.
Page 1 of 51
,Which hormone increases water reabsorption in the collecting ducts?
A. Insulin
B. Antidiuretic hormone
C. Thyroxine
D. Parathyroid hormone
Correct Answer: B. Antidiuretic hormone
Rationale: Antidiuretic hormone (ADH), also called vasopressin, increases the
permeability of the collecting ducts to water. This allows more water to move
from the tubular fluid back into the bloodstream, producing a smaller volume of
more concentrated urine. ADH therefore plays an important role in maintaining
body-fluid osmolality and volume.
Which part of the nephron is primarily responsible for the greatest amount of
filtered sodium and water reabsorption?
A. Proximal convoluted tubule
B. Distal convoluted tubule
C. Collecting duct
D. Renal pelvis
Correct Answer: A. Proximal convoluted tubule
Rationale: The proximal convoluted tubule reabsorbs a large proportion of the
filtered sodium and water, as well as substantial amounts of glucose, amino acids,
bicarbonate, and other substances. Its extensive reabsorptive capacity is essential
because the kidneys filter a very large volume of plasma each day and cannot
allow all filtered water and useful solutes to be lost in urine.
Which substance is normally prevented from passing through the glomerular
filtration barrier in significant amounts?
A. Sodium
B. Water
Page 2 of 51
,C. Glucose
D. Large plasma proteins
Correct Answer: D. Large plasma proteins
Rationale: The glomerular filtration barrier restricts the passage of cells and
most large plasma proteins. Small molecules such as water, electrolytes, glucose,
and urea can normally enter the filtrate. Significant protein loss in urine, or
proteinuria, can indicate damage to the glomerular filtration barrier.
What is the main nitrogenous waste product excreted by the kidneys?
A. Urea
B. Oxygen
C. Albumin
D. Glycogen
Correct Answer: A. Urea
Rationale: Urea is produced primarily by the liver as a result of protein
metabolism and is subsequently transported in the blood to the kidneys for
excretion. Blood urea nitrogen can be used as one indicator of renal function,
although it is influenced by factors such as hydration, protein intake, and
gastrointestinal bleeding.
Which renal process moves substances from the blood into the renal tubular
fluid after filtration?
A. Reabsorption
B. Secretion
C. Osmosis
D. Filtration
Correct Answer: B. Secretion
Rationale: Tubular secretion involves the movement of substances from
peritubular blood into the renal tubular fluid. Hydrogen ions, potassium under
certain circumstances, creatinine, and various medications can be secreted into
Page 3 of 51
, the tubular system. Secretion helps the kidneys eliminate substances that may not
have been adequately removed during glomerular filtration.
Which renal process returns useful substances from tubular fluid to the
bloodstream?
A. Filtration
B. Secretion
C. Reabsorption
D. Excretion
Correct Answer: C. Reabsorption
Rationale: Reabsorption returns water and useful solutes from the tubular
fluid into the circulation. Depending on the substance and nephron segment,
reabsorption may occur through passive or active mechanisms. This process
prevents valuable substances such as glucose, sodium, and water from being
unnecessarily lost in urine.
Which electrolyte is particularly important in determining resting membrane
potential and cardiac electrical activity?
A. Potassium
B. Chloride
C. Phosphate
D. Bicarbonate
Correct Answer: A. Potassium
Rationale: Potassium is the major intracellular cation and has a major
influence on the electrical gradient across cell membranes. Abnormal potassium
concentrations can therefore affect skeletal muscle, smooth muscle, and
especially cardiac conduction. The kidneys are central to potassium balance
because they regulate potassium excretion according to the body's needs.
What is the normal primary role of aldosterone in the kidney?
Page 4 of 51
