Chapter 03: The Cellular Environment: Fluids and Electrolytes, Acids and Bases
Rogers: McCance & Huether’s Pathophysiology, 9th Edition
MULTIPLE CHOICE
1. Why are infants most susceptible to significant losses in total body water?
a. Low body surface-to-body size ratio
b. Slow metabolic rate
c. Kidneys are not mature enough to counter fluid losses
d. Inability to communicate adequately when he or she is thirsty
ANS: C
Renal mechanisms that regulate fluid and electrolyte conservation are often not mature
enough to counter the losses; consequently, dehydration may rapidly develop. Infants can be
susceptible to changes in total body water because of their high metabolic rate and the
turnover of body fluids caused by their greater body surface area in proportion to their total
body size. An infant’s ability to communicate is limited and caregivers must become adept at
reading their signals.
DIF: Cognitive Level: Remembering
2. Why does obesity create a greater risk for dehydration in people?
a. Adipose cells contain little water because fat is water repelling.
b. The metabolic rate of obese adults is slower than the rate of lean adults.
c. The rate of urine output of obese adults is higher than in lean adults.
d. The thirst receptors of the hypothalamus do not function effectively.
ANS: A
The percentage of total body water (TBW) varies with the amount of body fat and age.
Because fat is water repelling (hydrophobic), very little water is contained in adipose cells.
Individuals with more body fat have proportionately less TBW and tend to be more
susceptible to fluid imbalances that cause dehydration.
DIF: Cognitive Level: Remembering
3. A patient’s blood gases reveal the following findings: pH 7.3; bicarbonate (HCO3) 27 mEq/L;
carbon dioxide (CO2) 58 mm Hg. What is the interpretation of these gases?
a. Respiratory alkalosis
b. Metabolic acidosis
c. Respiratory acidosis
d. Metabolic alkalosis
ANS: C
The values provided in this question characterize only acute uncompensated respiratory
acidosis. Respiratory acidosis is characterized by a low pH and high CO2. Alkalosis is
characterized by higher than normal pH. A metabolic acidosis would have a lower than
normal pH with a bicarbonate concentration of <22 mEq/L.
DIF: Cognitive Level: Understanding
, 4. Water movement between the intracellular fluid (ICF) compartment and the extracellular fluid
(ECF) compartment is primarily a function of what?
a. Osmotic forces
b. Plasma oncotic pressure
c. Antidiuretic hormone
d. Hydrostatic forces
ANS: A
The movement of water between the ICF and ECF compartments is primarily a function of
osmotic forces.
DIF: Cognitive Level: Remembering
5. In addition to osmosis, what force is involved in the movement of water between the plasma
and interstitial fluid spaces?
a. Oncotic pressure
b. Buffering
c. Net filtration
d. Hydrostatic pressure
ANS: D
Water moves between the plasma and interstitial fluid through the forces of only osmosis and
hydrostatic pressure, which occur across the capillary membrane. Buffers are substances that
can absorb excessive acid or base to minimize pH fluctuations. Net filtration is a term used to
identify fluid movement in relationship to the Starling hypothesis. Oncotic pressure
encourages water to cross the barrier of capillaries to enter the circulatory system.
DIF: Cognitive Level: Remembering
6. Venous obstruction is a cause of edema because of an increase in which pressure?
a. Capillary hydrostatic
b. Interstitial hydrostatic
c. Capillary oncotic
d. Interstitial oncotic
ANS: A
Venous obstruction can increase the hydrostatic pressure of fluid in the capillaries enough to
cause fluid to escape into the interstitial spaces. The remaining options are not causes of
edema resulting from venous obstruction.
DIF: Cognitive Level: Remembering
7. At the arterial end of capillaries, why does fluid move from the intravascular space into the
interstitial space?
a. Interstitial hydrostatic pressure is higher than the capillary hydrostatic pressure.
b. Capillary hydrostatic pressure is higher than the capillary oncotic pressure.
c. Interstitial oncotic pressure is higher than the interstitial hydrostatic pressure.
d. Capillary oncotic pressure is lower than the interstitial hydrostatic pressure.
ANS: B
At the arterial end of capillaries, fluid moves from the intravascular space into the interstitial
because capillary hydrostatic pressure is higher than the capillary oncotic pressure.
Rogers: McCance & Huether’s Pathophysiology, 9th Edition
MULTIPLE CHOICE
1. Why are infants most susceptible to significant losses in total body water?
a. Low body surface-to-body size ratio
b. Slow metabolic rate
c. Kidneys are not mature enough to counter fluid losses
d. Inability to communicate adequately when he or she is thirsty
ANS: C
Renal mechanisms that regulate fluid and electrolyte conservation are often not mature
enough to counter the losses; consequently, dehydration may rapidly develop. Infants can be
susceptible to changes in total body water because of their high metabolic rate and the
turnover of body fluids caused by their greater body surface area in proportion to their total
body size. An infant’s ability to communicate is limited and caregivers must become adept at
reading their signals.
DIF: Cognitive Level: Remembering
2. Why does obesity create a greater risk for dehydration in people?
a. Adipose cells contain little water because fat is water repelling.
b. The metabolic rate of obese adults is slower than the rate of lean adults.
c. The rate of urine output of obese adults is higher than in lean adults.
d. The thirst receptors of the hypothalamus do not function effectively.
ANS: A
The percentage of total body water (TBW) varies with the amount of body fat and age.
Because fat is water repelling (hydrophobic), very little water is contained in adipose cells.
Individuals with more body fat have proportionately less TBW and tend to be more
susceptible to fluid imbalances that cause dehydration.
DIF: Cognitive Level: Remembering
3. A patient’s blood gases reveal the following findings: pH 7.3; bicarbonate (HCO3) 27 mEq/L;
carbon dioxide (CO2) 58 mm Hg. What is the interpretation of these gases?
a. Respiratory alkalosis
b. Metabolic acidosis
c. Respiratory acidosis
d. Metabolic alkalosis
ANS: C
The values provided in this question characterize only acute uncompensated respiratory
acidosis. Respiratory acidosis is characterized by a low pH and high CO2. Alkalosis is
characterized by higher than normal pH. A metabolic acidosis would have a lower than
normal pH with a bicarbonate concentration of <22 mEq/L.
DIF: Cognitive Level: Understanding
, 4. Water movement between the intracellular fluid (ICF) compartment and the extracellular fluid
(ECF) compartment is primarily a function of what?
a. Osmotic forces
b. Plasma oncotic pressure
c. Antidiuretic hormone
d. Hydrostatic forces
ANS: A
The movement of water between the ICF and ECF compartments is primarily a function of
osmotic forces.
DIF: Cognitive Level: Remembering
5. In addition to osmosis, what force is involved in the movement of water between the plasma
and interstitial fluid spaces?
a. Oncotic pressure
b. Buffering
c. Net filtration
d. Hydrostatic pressure
ANS: D
Water moves between the plasma and interstitial fluid through the forces of only osmosis and
hydrostatic pressure, which occur across the capillary membrane. Buffers are substances that
can absorb excessive acid or base to minimize pH fluctuations. Net filtration is a term used to
identify fluid movement in relationship to the Starling hypothesis. Oncotic pressure
encourages water to cross the barrier of capillaries to enter the circulatory system.
DIF: Cognitive Level: Remembering
6. Venous obstruction is a cause of edema because of an increase in which pressure?
a. Capillary hydrostatic
b. Interstitial hydrostatic
c. Capillary oncotic
d. Interstitial oncotic
ANS: A
Venous obstruction can increase the hydrostatic pressure of fluid in the capillaries enough to
cause fluid to escape into the interstitial spaces. The remaining options are not causes of
edema resulting from venous obstruction.
DIF: Cognitive Level: Remembering
7. At the arterial end of capillaries, why does fluid move from the intravascular space into the
interstitial space?
a. Interstitial hydrostatic pressure is higher than the capillary hydrostatic pressure.
b. Capillary hydrostatic pressure is higher than the capillary oncotic pressure.
c. Interstitial oncotic pressure is higher than the interstitial hydrostatic pressure.
d. Capillary oncotic pressure is lower than the interstitial hydrostatic pressure.
ANS: B
At the arterial end of capillaries, fluid moves from the intravascular space into the interstitial
because capillary hydrostatic pressure is higher than the capillary oncotic pressure.
