Principles of Anatomy and Physiology Test Bank 16th
Edition | Tortora & Derrickson EXAM with Questions
and Answers/Plus a Rationale Updated 2026
A+/Instant Download PDF
EXAM COVERAGE - 1. Cellular Level of Organization - 2. Tissue Level
of Organization - 3. The Integumentary System - 4. The Skeletal System -
5. The Muscular System - 6. The Nervous System - 7. The Endocrine
System - 8. The Cardiovascular System - 9. The Respiratory System - 10.
The Digestive System - 11. The Urinary System - 12. Fluid, Electrolyte,
and Acid-Base Homeostasis - 13. The Reproductive Systems
1. A 45-year-old patient presents with chronic muscle weakness and fatigue. Laboratory tests reveal
elevated levels of intracellular sodium and decreased intracellular potassium in skeletal muscle
cells. Which of the following mechanisms is most likely impaired, leading to this specific ion
imbalance?
A. Facilitated diffusion of sodium through voltage-gated channels
B. Primary active transport via the Na+/K+ ATPase pump
C. Secondary active transport via sodium-calcium exchangers
D. Simple diffusion of potassium through leak channels
CORRECT ANSWER : B
Rationale: The Na+/K+ ATPase pump uses ATP (primary active transport) to move 3 Na+ out
of the cell and 2 K+ into the cell against their concentration gradients, maintaining the resting
membrane potential. Impairment of this pump leads to intracellular sodium accumulation and
potassium depletion. Options A and D involve passive transport along gradients, which would
not establish this specific imbalance. Option C relies on the sodium gradient established by the
Na+/K+ pump, making the ATPase pump the primary failure point.
2. During a surgical procedure on the anterior neck, a surgeon inadvertently damages the
parathyroid glands. Within 24 hours, the patient begins experiencing severe muscle spasms and a
positive Chvostek's sign. Which physiological response is primarily failing in this patient?
A. Stimulation of osteoclast activity and increased renal reabsorption of calcium
B. Inhibition of osteoblast activity and increased synthesis of calcitonin
, C. Enhanced absorption of calcium from the gastrointestinal tract independent of calcitriol
D. Suppression of renal excretion of phosphate and increased excretion of calcium
CORRECT ANSWER : A
Rationale: The parathyroid glands secrete parathyroid hormone (PTH) in response to low blood
calcium levels. PTH increases blood calcium by stimulating osteoclast activity (releasing
calcium from bone) and increasing calcium reabsorption in the kidneys. Damage to the glands
causes hypocalcemia, leading to tetany (muscle spasms). Option B is incorrect as calcitonin
decreases blood calcium. Option C is incorrect because PTH stimulates calcitriol synthesis to
enhance GI absorption. Option D represents the opposite of PTH's physiological effect.
3. A 60-year-old male with a history of severe chronic obstructive pulmonary disease (COPD)
presents with arterial blood gas results indicating a pH of 7.31, PaCO2 of 58 mmHg, and HCO3-
of 28 mEq/L. Which compensatory mechanism is the body currently utilizing to address this
acid-base imbalance?
A. Hyperventilation to increase the elimination of CO2 from the lungs
B. Increased renal tubular reabsorption of bicarbonate and excretion of hydrogen ions
C. Decreased renal secretion of hydrogen ions into the tubular fluid
D. Hypoventilation to retain CO2 and increase plasma carbonic acid levels
CORRECT ANSWER : B
Rationale: The patient is experiencing respiratory acidosis due to COPD, indicated by a low pH
and elevated PaCO2. The elevated HCO3- indicates that metabolic (renal) compensation is
occurring. The kidneys compensate for respiratory acidosis by increasing the reabsorption and
generation of bicarbonate (HCO3-) and excreting more hydrogen ions (H+). Option A is
physically compromised due to the underlying COPD. Option C would worsen the acidosis.
Option D would further increase PaCO2, exacerbating the condition.
4. In a patient suffering from left-sided heart failure, fluid accumulates in the pulmonary interstitial
spaces and alveoli. According to Starling's forces, which pressure change in the pulmonary
capillaries is the primary driver for this onset of pulmonary edema?
A. Decreased blood colloid osmotic pressure
B. Increased interstitial fluid hydrostatic pressure
C. Increased blood hydrostatic pressure
D. Decreased interstitial fluid osmotic pressure
, CORRECT ANSWER : C
Rationale: Left-sided heart failure causes blood to back up into the pulmonary circulation,
significantly increasing the blood hydrostatic pressure (capillary fluid pressure) within the
pulmonary capillaries. This pathological pressure forces excess fluid out of the capillaries and
into the interstitial spaces and alveoli, causing pulmonary edema. Option A typically results
from hypoproteinemia (e.g., liver failure) rather than heart failure. Options B and D do not act
as the primary driving forces to move fluid out of the capillaries into the alveolar spaces.
5. A patient is administered a pharmacological agent that specifically acts as an antagonist at
muscarinic cholinergic receptors. Which of the following physiological effects would most likely
be observed upon systemic absorption?
A. Constriction of the pupils (miosis)
B. Decreased gastrointestinal motility and glandular secretions
C. Significant decrease in resting heart rate (bradycardia)
D. Enhanced contraction of somatic skeletal muscle fibers
CORRECT ANSWER : B
Rationale: Muscarinic receptors are primarily targeted by the postganglionic fibers of the
parasympathetic nervous system, which promotes "rest and digest" activities. Antagonizing these
receptors blocks parasympathetic effects, leading directly to decreased GI motility and
secretions. Option A is incorrect because muscarinic antagonists cause pupillary dilation
(mydriasis). Option C is incorrect because blocking parasympathetic tone to the heart removes
vagal inhibition, causing an increase in heart rate. Option D is incorrect because skeletal muscle
contraction is mediated by nicotinic cholinergic receptors, not muscarinic.
6. A 32-year-old female presents with central obesity, moon facies, and hypertension. Laboratory
results show elevated serum cortisol that is not suppressed by a low-dose dexamethasone test,
but is suppressed by a high-dose dexamethasone test. ACTH levels are also elevated. Based on
the endocrine feedback loop, what is the primary anatomical source of this patient's pathology?
A. Primary hypersecretion from the adrenal cortex zona fasciculata
B. An adenoma in the anterior pituitary gland secreting excess corticotropin
C. Ectopic ACTH secretion from a small cell lung carcinoma
D. Hypothalamic tumor resulting in excessive corticotropin-releasing hormone (CRH)
CORRECT ANSWER : B
, Rationale: The patient exhibits Cushing's disease, characterized by ACTH-dependent
hypercortisolism. The key differentiating factor is the high-dose dexamethasone test: pituitary
adenomas (Option B) typically retain some negative feedback sensitivity and will suppress
ACTH/cortisol secretion at high doses. Ectopic ACTH tumors (Option C) are autonomous and
do not suppress. Primary adrenal tumors (Option A) would present with low, fully suppressed
ACTH levels due to negative feedback. Hypothalamic tumors (Option D) are exceptionally rare
causes of this specific suppression pattern.
7. During an experimental neurophysiology study, an isolated motor neuron is stimulated, and its
action potential is recorded. If the extracellular concentration of potassium is artificially doubled
around the axon, how will this specific manipulation most directly alter the neuron's subsequent
action potentials?
A. The amplitude of the depolarization phase will dramatically increase.
B. The threshold potential will become significantly more negative.
C. The resting membrane potential will become less negative, bringing it closer to
threshold.
D. The hyperpolarization phase will become significantly deeper and more prolonged.
CORRECT ANSWER : C
Rationale: The resting membrane potential is highly dependent on the potassium concentration
gradient across the cell membrane. Doubling extracellular potassium (hyperkalemia) decreases
the concentration gradient, which reduces the efflux of potassium through leak channels. This
causes the resting membrane potential to become less negative (depolarize), moving it closer to
the threshold. Option A is incorrect because sodium primarily dictates the depolarization
amplitude. Option B is incorrect as the threshold relies on voltage-gated sodium channel
conformation. Option D is incorrect because a reduced gradient would lessen, not deepen,
hyperpolarization.
8. A patient is prescribed a proton pump inhibitor (PPI) for the treatment of severe
gastroesophageal reflux disease (GERD). Over time, this pharmacological intervention will most
significantly impair the absorption of which essential nutrient, and through what specific
mechanism?
A. Calcium, due to the inhibition of active transport channels in the duodenum
B. Iron, due to decreased conversion of ferric (Fe3+) to ferrous (Fe2+) iron
C. Vitamin B12, secondary to decreased intrinsic factor secretion and impaired protein
dissociation
D. Vitamin D, due to blocked activation of cholecalciferol in the gastric mucosa
Edition | Tortora & Derrickson EXAM with Questions
and Answers/Plus a Rationale Updated 2026
A+/Instant Download PDF
EXAM COVERAGE - 1. Cellular Level of Organization - 2. Tissue Level
of Organization - 3. The Integumentary System - 4. The Skeletal System -
5. The Muscular System - 6. The Nervous System - 7. The Endocrine
System - 8. The Cardiovascular System - 9. The Respiratory System - 10.
The Digestive System - 11. The Urinary System - 12. Fluid, Electrolyte,
and Acid-Base Homeostasis - 13. The Reproductive Systems
1. A 45-year-old patient presents with chronic muscle weakness and fatigue. Laboratory tests reveal
elevated levels of intracellular sodium and decreased intracellular potassium in skeletal muscle
cells. Which of the following mechanisms is most likely impaired, leading to this specific ion
imbalance?
A. Facilitated diffusion of sodium through voltage-gated channels
B. Primary active transport via the Na+/K+ ATPase pump
C. Secondary active transport via sodium-calcium exchangers
D. Simple diffusion of potassium through leak channels
CORRECT ANSWER : B
Rationale: The Na+/K+ ATPase pump uses ATP (primary active transport) to move 3 Na+ out
of the cell and 2 K+ into the cell against their concentration gradients, maintaining the resting
membrane potential. Impairment of this pump leads to intracellular sodium accumulation and
potassium depletion. Options A and D involve passive transport along gradients, which would
not establish this specific imbalance. Option C relies on the sodium gradient established by the
Na+/K+ pump, making the ATPase pump the primary failure point.
2. During a surgical procedure on the anterior neck, a surgeon inadvertently damages the
parathyroid glands. Within 24 hours, the patient begins experiencing severe muscle spasms and a
positive Chvostek's sign. Which physiological response is primarily failing in this patient?
A. Stimulation of osteoclast activity and increased renal reabsorption of calcium
B. Inhibition of osteoblast activity and increased synthesis of calcitonin
, C. Enhanced absorption of calcium from the gastrointestinal tract independent of calcitriol
D. Suppression of renal excretion of phosphate and increased excretion of calcium
CORRECT ANSWER : A
Rationale: The parathyroid glands secrete parathyroid hormone (PTH) in response to low blood
calcium levels. PTH increases blood calcium by stimulating osteoclast activity (releasing
calcium from bone) and increasing calcium reabsorption in the kidneys. Damage to the glands
causes hypocalcemia, leading to tetany (muscle spasms). Option B is incorrect as calcitonin
decreases blood calcium. Option C is incorrect because PTH stimulates calcitriol synthesis to
enhance GI absorption. Option D represents the opposite of PTH's physiological effect.
3. A 60-year-old male with a history of severe chronic obstructive pulmonary disease (COPD)
presents with arterial blood gas results indicating a pH of 7.31, PaCO2 of 58 mmHg, and HCO3-
of 28 mEq/L. Which compensatory mechanism is the body currently utilizing to address this
acid-base imbalance?
A. Hyperventilation to increase the elimination of CO2 from the lungs
B. Increased renal tubular reabsorption of bicarbonate and excretion of hydrogen ions
C. Decreased renal secretion of hydrogen ions into the tubular fluid
D. Hypoventilation to retain CO2 and increase plasma carbonic acid levels
CORRECT ANSWER : B
Rationale: The patient is experiencing respiratory acidosis due to COPD, indicated by a low pH
and elevated PaCO2. The elevated HCO3- indicates that metabolic (renal) compensation is
occurring. The kidneys compensate for respiratory acidosis by increasing the reabsorption and
generation of bicarbonate (HCO3-) and excreting more hydrogen ions (H+). Option A is
physically compromised due to the underlying COPD. Option C would worsen the acidosis.
Option D would further increase PaCO2, exacerbating the condition.
4. In a patient suffering from left-sided heart failure, fluid accumulates in the pulmonary interstitial
spaces and alveoli. According to Starling's forces, which pressure change in the pulmonary
capillaries is the primary driver for this onset of pulmonary edema?
A. Decreased blood colloid osmotic pressure
B. Increased interstitial fluid hydrostatic pressure
C. Increased blood hydrostatic pressure
D. Decreased interstitial fluid osmotic pressure
, CORRECT ANSWER : C
Rationale: Left-sided heart failure causes blood to back up into the pulmonary circulation,
significantly increasing the blood hydrostatic pressure (capillary fluid pressure) within the
pulmonary capillaries. This pathological pressure forces excess fluid out of the capillaries and
into the interstitial spaces and alveoli, causing pulmonary edema. Option A typically results
from hypoproteinemia (e.g., liver failure) rather than heart failure. Options B and D do not act
as the primary driving forces to move fluid out of the capillaries into the alveolar spaces.
5. A patient is administered a pharmacological agent that specifically acts as an antagonist at
muscarinic cholinergic receptors. Which of the following physiological effects would most likely
be observed upon systemic absorption?
A. Constriction of the pupils (miosis)
B. Decreased gastrointestinal motility and glandular secretions
C. Significant decrease in resting heart rate (bradycardia)
D. Enhanced contraction of somatic skeletal muscle fibers
CORRECT ANSWER : B
Rationale: Muscarinic receptors are primarily targeted by the postganglionic fibers of the
parasympathetic nervous system, which promotes "rest and digest" activities. Antagonizing these
receptors blocks parasympathetic effects, leading directly to decreased GI motility and
secretions. Option A is incorrect because muscarinic antagonists cause pupillary dilation
(mydriasis). Option C is incorrect because blocking parasympathetic tone to the heart removes
vagal inhibition, causing an increase in heart rate. Option D is incorrect because skeletal muscle
contraction is mediated by nicotinic cholinergic receptors, not muscarinic.
6. A 32-year-old female presents with central obesity, moon facies, and hypertension. Laboratory
results show elevated serum cortisol that is not suppressed by a low-dose dexamethasone test,
but is suppressed by a high-dose dexamethasone test. ACTH levels are also elevated. Based on
the endocrine feedback loop, what is the primary anatomical source of this patient's pathology?
A. Primary hypersecretion from the adrenal cortex zona fasciculata
B. An adenoma in the anterior pituitary gland secreting excess corticotropin
C. Ectopic ACTH secretion from a small cell lung carcinoma
D. Hypothalamic tumor resulting in excessive corticotropin-releasing hormone (CRH)
CORRECT ANSWER : B
, Rationale: The patient exhibits Cushing's disease, characterized by ACTH-dependent
hypercortisolism. The key differentiating factor is the high-dose dexamethasone test: pituitary
adenomas (Option B) typically retain some negative feedback sensitivity and will suppress
ACTH/cortisol secretion at high doses. Ectopic ACTH tumors (Option C) are autonomous and
do not suppress. Primary adrenal tumors (Option A) would present with low, fully suppressed
ACTH levels due to negative feedback. Hypothalamic tumors (Option D) are exceptionally rare
causes of this specific suppression pattern.
7. During an experimental neurophysiology study, an isolated motor neuron is stimulated, and its
action potential is recorded. If the extracellular concentration of potassium is artificially doubled
around the axon, how will this specific manipulation most directly alter the neuron's subsequent
action potentials?
A. The amplitude of the depolarization phase will dramatically increase.
B. The threshold potential will become significantly more negative.
C. The resting membrane potential will become less negative, bringing it closer to
threshold.
D. The hyperpolarization phase will become significantly deeper and more prolonged.
CORRECT ANSWER : C
Rationale: The resting membrane potential is highly dependent on the potassium concentration
gradient across the cell membrane. Doubling extracellular potassium (hyperkalemia) decreases
the concentration gradient, which reduces the efflux of potassium through leak channels. This
causes the resting membrane potential to become less negative (depolarize), moving it closer to
the threshold. Option A is incorrect because sodium primarily dictates the depolarization
amplitude. Option B is incorrect as the threshold relies on voltage-gated sodium channel
conformation. Option D is incorrect because a reduced gradient would lessen, not deepen,
hyperpolarization.
8. A patient is prescribed a proton pump inhibitor (PPI) for the treatment of severe
gastroesophageal reflux disease (GERD). Over time, this pharmacological intervention will most
significantly impair the absorption of which essential nutrient, and through what specific
mechanism?
A. Calcium, due to the inhibition of active transport channels in the duodenum
B. Iron, due to decreased conversion of ferric (Fe3+) to ferrous (Fe2+) iron
C. Vitamin B12, secondary to decreased intrinsic factor secretion and impaired protein
dissociation
D. Vitamin D, due to blocked activation of cholecalciferol in the gastric mucosa
