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NUR 101 COMPREHENSIVE STUDY GUIDE: FLUID &
ELECTROLYTE BALANCE EXAM 250 QUESTIONS LATEST
VERSION QUESTIONS AND ANSWERS 2026 EDITION
NUR 101 COMPREHENSIVE STUDY GUIDE: FLUID & ELECTROLYTE BALANCE EXAM
QUESTIONS 1-50: FLUID COMPARTMENTS, MOVEMENT, AND REGULATION
1. A nurse is reviewing the distribution of body fluids with a nursing student. Which
statement accurately describes the proportion of total body water (TBW) in a
healthy adult?
A. Intracellular fluid accounts for approximately one-third of total body water
B. Extracellular fluid accounts for approximately two-thirds of total body water
C. Intracellular fluid accounts for approximately two-thirds of total body water
D. Intracellular and extracellular fluids are present in equal proportions
Correct Answer: C
Rationale: In a healthy adult, approximately two-thirds (about 60-65%) of total body
water is contained within the cells as intracellular fluid (ICF), and about one-third
(approximately 35-40%) is in the extracellular compartment . Extracellular fluid (ECF)
includes interstitial fluid, intravascular (plasma), and transcellular fluids.
Understanding this distribution is fundamental for recognizing fluid shifts in various
disease states.
2. A nursing student is studying fluid movement across capillary membranes.
Which statement correctly describes the relationship between hydrostatic and
osmotic pressure in the capillaries?
A. Hydrostatic pressure pulls water into the capillary, while osmotic pressure pushes
water out
B. Hydrostatic pressure pushes water out of the capillary, while osmotic pressure pulls
water in
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C. Both hydrostatic and osmotic pressure push water out of the capillary
D. Both hydrostatic and osmotic pressure pull water into the capillary
Correct Answer: B
Rationale: Hydrostatic pressure is the force of fluid pressing against the blood vessel
wall, pushing water out of the capillary into the interstitial space. Osmotic pressure
(oncotic pressure) is the pulling force created by solutes, primarily albumin, which
draws water back into the capillary . This dynamic balance (Starling's forces) maintains
proper fluid distribution between the vascular and interstitial compartments. When this
balance is disrupted, edema or dehydration can result.
3. A client is diagnosed with dehydration. The nurse understands that the body's
first line of defense against dehydration is:
A. Increased urine output
B. Stimulation of the renin-angiotensin-aldosterone system
C. The thirst mechanism
D. Increased secretion of antidiuretic hormone (ADH)
Correct Answer: C
Rationale: The thirst mechanism is the body's primary first-line defense against
dehydration. When serum osmolality increases, osmoreceptors in the hypothalamus
are stimulated, triggering the sensation of thirst and prompting fluid intake. ADH
secretion (D) and the RAAS (B) are secondary compensatory responses that conserve
water but are slower to act . Increased urine output (A) would worsen dehydration.
4. A patient with cirrhosis has low serum albumin levels. The nurse anticipates
which fluid shift based on this finding?
A. Fluid movement from the interstitial space into the vascular space
B. Fluid movement from the vascular space into the interstitial space
C. No change in fluid distribution
D. Fluid movement from the intracellular space into the vascular space
Correct Answer: B
Rationale: Albumin is a major plasma protein that contributes to oncotic (colloid
osmotic) pressure, which pulls water into the vascular space. When albumin is low, as
in liver disease, oncotic pressure decreases, allowing fluid to leak from the vascular
space into the interstitial space . This results in edema and can lead to third spacing
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(ascites in cirrhosis). Administration of albumin is used therapeutically to restore
oncotic pressure and pull fluid back into the vascular space .
5. A nurse is reviewing the mechanisms of fluid movement. Which process involves
the movement of water across a semipermeable membrane from an area of low
solute concentration to an area of high solute concentration?
A. Diffusion
B. Osmosis
C. Filtration
D. Active transport
Correct Answer: B
Rationale: Osmosis is the passive movement of water across a semipermeable
membrane from an area of lower solute concentration (higher water concentration) to
an area of higher solute concentration (lower water concentration) until equilibrium is
reached . Diffusion (A) is the movement of solutes from high to low concentration.
Filtration (C) involves movement of both fluid and solutes from high to low pressure.
Active transport (D) requires ATP and moves substances against a concentration
gradient.
6. Which statement correctly describes the composition of intracellular and
extracellular fluids?
A. Intracellular fluid contains higher concentrations of sodium and chloride
B. Extracellular fluid contains higher concentrations of potassium and magnesium
C. Intracellular fluid contains higher concentrations of potassium and magnesium
D. Extracellular and intracellular fluids have identical electrolyte compositions
Correct Answer: C
Rationale: The ICF has higher concentrations of potassium (K+), magnesium (Mg2+),
and phosphate, while the ECF has higher concentrations of sodium (Na+), chloride (Cl-
), and bicarbonate. This distribution is maintained by the sodium-potassium pump .
Understanding this distribution is essential for interpreting electrolyte imbalances and
guiding replacement therapy, as potassium is primarily an intracellular cation and
sodium is primarily extracellular.
7. A nurse is teaching a client about the renin-angiotensin-aldosterone system
(RAAS). Which statement correctly describes the function of this system?
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A. It promotes sodium and water excretion to decrease blood pressure
B. It promotes vasodilation and increased urine output
C. It promotes sodium and water retention and vasoconstriction to increase blood
pressure
D. It only affects potassium levels without impacting fluid balance
Correct Answer: C
Rationale: The RAAS is activated in response to decreased renal perfusion, low blood
pressure, or low sodium. Renin converts angiotensinogen to angiotensin I, then ACE
converts it to angiotensin II, causing vasoconstriction and stimulating aldosterone
release . Aldosterone promotes sodium and water reabsorption (and potassium
excretion) in the kidneys, increasing blood volume and pressure. Natriuretic peptides
(not RAAS) promote sodium and water excretion .
8. A patient has syndrome of inappropriate antidiuretic hormone (SIADH). The
nurse anticipates which fluid and electrolyte imbalance?
A. Hypervolemia and hyponatremia
B. Hypovolemia and hypernatremia
C. Hypervolemia and hypernatremia
D. Hypovolemia and hyponatremia
Correct Answer: A
Rationale: ADH promotes water reabsorption in the kidneys. In SIADH, excessive ADH
leads to water retention, dilutional hyponatremia (low serum sodium due to excess
water), and hypervolemia (fluid overload) . Conversely, diabetes insipidus (deficient
ADH) causes hypovolemia and hypernatremia. Understanding this contrast is essential
for exam preparation.
9. Which of the following is an example of an isotonic IV solution?
A. 0.45% sodium chloride (half-normal saline)
B. 0.9% sodium chloride (normal saline)
C. 3% sodium chloride
D. 5% dextrose in water (D5W)
Correct Answer: B
Rationale: 0.9% sodium chloride (normal saline) is an isotonic solution with an
osmolarity similar to plasma . It expands the intravascular compartment without
causing fluid shifts between compartments. 0.45% sodium chloride (A) is hypotonic.
NUR 101 COMPREHENSIVE STUDY GUIDE: FLUID &
ELECTROLYTE BALANCE EXAM 250 QUESTIONS LATEST
VERSION QUESTIONS AND ANSWERS 2026 EDITION
NUR 101 COMPREHENSIVE STUDY GUIDE: FLUID & ELECTROLYTE BALANCE EXAM
QUESTIONS 1-50: FLUID COMPARTMENTS, MOVEMENT, AND REGULATION
1. A nurse is reviewing the distribution of body fluids with a nursing student. Which
statement accurately describes the proportion of total body water (TBW) in a
healthy adult?
A. Intracellular fluid accounts for approximately one-third of total body water
B. Extracellular fluid accounts for approximately two-thirds of total body water
C. Intracellular fluid accounts for approximately two-thirds of total body water
D. Intracellular and extracellular fluids are present in equal proportions
Correct Answer: C
Rationale: In a healthy adult, approximately two-thirds (about 60-65%) of total body
water is contained within the cells as intracellular fluid (ICF), and about one-third
(approximately 35-40%) is in the extracellular compartment . Extracellular fluid (ECF)
includes interstitial fluid, intravascular (plasma), and transcellular fluids.
Understanding this distribution is fundamental for recognizing fluid shifts in various
disease states.
2. A nursing student is studying fluid movement across capillary membranes.
Which statement correctly describes the relationship between hydrostatic and
osmotic pressure in the capillaries?
A. Hydrostatic pressure pulls water into the capillary, while osmotic pressure pushes
water out
B. Hydrostatic pressure pushes water out of the capillary, while osmotic pressure pulls
water in
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C. Both hydrostatic and osmotic pressure push water out of the capillary
D. Both hydrostatic and osmotic pressure pull water into the capillary
Correct Answer: B
Rationale: Hydrostatic pressure is the force of fluid pressing against the blood vessel
wall, pushing water out of the capillary into the interstitial space. Osmotic pressure
(oncotic pressure) is the pulling force created by solutes, primarily albumin, which
draws water back into the capillary . This dynamic balance (Starling's forces) maintains
proper fluid distribution between the vascular and interstitial compartments. When this
balance is disrupted, edema or dehydration can result.
3. A client is diagnosed with dehydration. The nurse understands that the body's
first line of defense against dehydration is:
A. Increased urine output
B. Stimulation of the renin-angiotensin-aldosterone system
C. The thirst mechanism
D. Increased secretion of antidiuretic hormone (ADH)
Correct Answer: C
Rationale: The thirst mechanism is the body's primary first-line defense against
dehydration. When serum osmolality increases, osmoreceptors in the hypothalamus
are stimulated, triggering the sensation of thirst and prompting fluid intake. ADH
secretion (D) and the RAAS (B) are secondary compensatory responses that conserve
water but are slower to act . Increased urine output (A) would worsen dehydration.
4. A patient with cirrhosis has low serum albumin levels. The nurse anticipates
which fluid shift based on this finding?
A. Fluid movement from the interstitial space into the vascular space
B. Fluid movement from the vascular space into the interstitial space
C. No change in fluid distribution
D. Fluid movement from the intracellular space into the vascular space
Correct Answer: B
Rationale: Albumin is a major plasma protein that contributes to oncotic (colloid
osmotic) pressure, which pulls water into the vascular space. When albumin is low, as
in liver disease, oncotic pressure decreases, allowing fluid to leak from the vascular
space into the interstitial space . This results in edema and can lead to third spacing
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(ascites in cirrhosis). Administration of albumin is used therapeutically to restore
oncotic pressure and pull fluid back into the vascular space .
5. A nurse is reviewing the mechanisms of fluid movement. Which process involves
the movement of water across a semipermeable membrane from an area of low
solute concentration to an area of high solute concentration?
A. Diffusion
B. Osmosis
C. Filtration
D. Active transport
Correct Answer: B
Rationale: Osmosis is the passive movement of water across a semipermeable
membrane from an area of lower solute concentration (higher water concentration) to
an area of higher solute concentration (lower water concentration) until equilibrium is
reached . Diffusion (A) is the movement of solutes from high to low concentration.
Filtration (C) involves movement of both fluid and solutes from high to low pressure.
Active transport (D) requires ATP and moves substances against a concentration
gradient.
6. Which statement correctly describes the composition of intracellular and
extracellular fluids?
A. Intracellular fluid contains higher concentrations of sodium and chloride
B. Extracellular fluid contains higher concentrations of potassium and magnesium
C. Intracellular fluid contains higher concentrations of potassium and magnesium
D. Extracellular and intracellular fluids have identical electrolyte compositions
Correct Answer: C
Rationale: The ICF has higher concentrations of potassium (K+), magnesium (Mg2+),
and phosphate, while the ECF has higher concentrations of sodium (Na+), chloride (Cl-
), and bicarbonate. This distribution is maintained by the sodium-potassium pump .
Understanding this distribution is essential for interpreting electrolyte imbalances and
guiding replacement therapy, as potassium is primarily an intracellular cation and
sodium is primarily extracellular.
7. A nurse is teaching a client about the renin-angiotensin-aldosterone system
(RAAS). Which statement correctly describes the function of this system?
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A. It promotes sodium and water excretion to decrease blood pressure
B. It promotes vasodilation and increased urine output
C. It promotes sodium and water retention and vasoconstriction to increase blood
pressure
D. It only affects potassium levels without impacting fluid balance
Correct Answer: C
Rationale: The RAAS is activated in response to decreased renal perfusion, low blood
pressure, or low sodium. Renin converts angiotensinogen to angiotensin I, then ACE
converts it to angiotensin II, causing vasoconstriction and stimulating aldosterone
release . Aldosterone promotes sodium and water reabsorption (and potassium
excretion) in the kidneys, increasing blood volume and pressure. Natriuretic peptides
(not RAAS) promote sodium and water excretion .
8. A patient has syndrome of inappropriate antidiuretic hormone (SIADH). The
nurse anticipates which fluid and electrolyte imbalance?
A. Hypervolemia and hyponatremia
B. Hypovolemia and hypernatremia
C. Hypervolemia and hypernatremia
D. Hypovolemia and hyponatremia
Correct Answer: A
Rationale: ADH promotes water reabsorption in the kidneys. In SIADH, excessive ADH
leads to water retention, dilutional hyponatremia (low serum sodium due to excess
water), and hypervolemia (fluid overload) . Conversely, diabetes insipidus (deficient
ADH) causes hypovolemia and hypernatremia. Understanding this contrast is essential
for exam preparation.
9. Which of the following is an example of an isotonic IV solution?
A. 0.45% sodium chloride (half-normal saline)
B. 0.9% sodium chloride (normal saline)
C. 3% sodium chloride
D. 5% dextrose in water (D5W)
Correct Answer: B
Rationale: 0.9% sodium chloride (normal saline) is an isotonic solution with an
osmolarity similar to plasma . It expands the intravascular compartment without
causing fluid shifts between compartments. 0.45% sodium chloride (A) is hypotonic.
