BIO 256 Advanced Prep: Master Human Physiology
Practice Questions & Detailed Explanations
Subject: Human Physiology
Subtopic: Neurophysiology, Cardiovascular Dynamics, and Renal Homeostasis
Question 1: A patient presents with a specific neurological deficit where they can comprehend
language but cannot produce coherent speech, despite having intact vocal cords and motor
control of the articulatory muscles. If this is due to an ischemic stroke, which specific cortical
area is most likely affected, and what is the functional result of this lesion?
A) Wernicke’s area; resulting in fluent aphasia where the patient produces meaningless, rapid
speech.
B) Broca’s area; resulting in non-fluent, expressive aphasia where the patient struggles to form
grammatical sentences.
C) Primary motor cortex; resulting in dysarthria due to paralysis of the tongue and laryngeal
muscles.
D) Arcuate fasciculus; resulting in conduction aphasia, characterized by the inability to repeat
spoken words.
Correct Answer: B) Broca’s area; resulting in non-fluent, expressive aphasia where the
patient struggles to form grammatical sentences.
Explanation: Broca’s area, located in the posterior inferior frontal gyrus of the dominant
hemisphere, is responsible for motor speech planning. Lesions here cause expressive aphasia,
where comprehension remains intact, but speech output is labored and telegraphic. Option A
describes Wernicke’s aphasia, where comprehension is impaired. Option C refers to a motor
execution deficit (dysarthria) rather than a language processing deficit. Option D refers to the
fiber tract connecting the two, causing failure to repeat, which is a different clinical syndrome.
Question 2: During an action potential in a large myelinated axon, which of the following best
describes the physiological basis for the "absolute refractory period"?
A) Continued activity of the Na+/K+ ATPase pump attempting to restore resting membrane
potential.
B) The delayed opening of voltage-gated potassium channels causing hyperpolarization.
C) The inactivation state of voltage-gated sodium channels that cannot be opened regardless of
stimulus strength.
,D) The increased chloride conductance leading to an inhibitory postsynaptic potential.
Correct Answer: C) The inactivation state of voltage-gated sodium channels that cannot be
opened regardless of stimulus strength.
Explanation: The absolute refractory period is strictly defined by the time during which voltage-
gated sodium channels are in their inactivated state. Even a suprathreshold stimulus cannot
elicit another action potential because the inactivation gate "plugs" the channel. Option B
describes the mechanism for the relative refractory period (hyperpolarization). Option A is a
continuous maintenance process, not the primary cause of the refractory period.
Question 3: Which of the following hemodynamic changes would most significantly increase
the myocardial oxygen demand of a patient with stable angina?
A) A decrease in left ventricular end-diastolic volume.
B) An increase in heart rate.
C) An increase in diastolic filling time.
D) A decrease in left ventricular wall thickness.
Correct Answer: B) An increase in heart rate.
Explanation: Myocardial oxygen demand is primarily determined by heart rate, wall tension
(Law of Laplace), and contractility. Heart rate is a dominant factor because it increases the
metabolic rate of the heart while simultaneously reducing the time available for coronary
perfusion (which occurs during diastole). Options A and C would generally decrease oxygen
demand, and D would decrease wall tension, thus decreasing demand.
Question 4: In a patient experiencing a significant reduction in glomerular filtration rate (GFR)
due to renal artery stenosis, which mechanism is primarily responsible for the compensatory
maintenance of GFR?
A) Afferent arteriolar vasoconstriction via the sympathetic nervous system.
B) Efferent arteriolar vasoconstriction mediated by Angiotensin II.
C) Vasodilation of the afferent arteriole by Prostaglandins.
D) Increased release of Atrial Natriuretic Peptide (ANP).
Correct Answer: B) Efferent arteriolar vasoconstriction mediated by Angiotensin II.
Explanation: Renal artery stenosis leads to decreased renal perfusion pressure, triggering the
Renin-Angiotensin-Aldosterone System (RAAS). Angiotensin II preferentially constricts the
, efferent arteriole, which increases the hydrostatic pressure in the glomerular capillaries, thereby
maintaining GFR despite low inflow. Option A would decrease GFR. Option C is a protective
mechanism for flow, but the direct hormonal regulation of pressure to maintain GFR is primarily
efferent control.
Question 5: A patient shows hyperkalemia with EKG changes. Which shift in the tubular
handling of potassium is the most likely physiological consequence of the body’s attempt to
manage this electrolyte imbalance via the distal convoluted tubule?
A) Increased activity of the Na+/K+/2Cl- symporter.
B) Decreased secretion of aldosterone by the adrenal cortex.
C) Increased activity of the ENaC (epithelial sodium channels) and ROMK (renal outer
medullary potassium) channels.
D) Inhibition of the H+/K+ ATPase in the intercalated cells.
Correct Answer: C) Increased activity of the ENaC (epithelial sodium channels) and ROMK
(renal outer medullary potassium) channels.
Explanation: Hyperkalemia directly stimulates the release of aldosterone. Aldosterone acts on
the principal cells of the collecting duct to increase the expression of ENaC (to reabsorb Na+)
and ROMK channels (to secrete K+). This process promotes potassium excretion to lower
plasma levels. Options A and D do not represent the primary mechanism for renal potassium
regulation in this context.
6. Renal Physiology & Cardiovascular Integration
Question 6: A patient with chronic hypertension presents with edema. A diuretic that acts on the
thick ascending limb of the loop of Henle is administered. What is the molecular mechanism of
this drug, and why might it cause hypokalemia?
A) Inhibition of the Na+/Cl- symporter; causing excessive Na+ delivery to the distal tubule.
B) Inhibition of the Na+/K+/2Cl- cotransporter; causing increased Na+ delivery to the distal
tubule and subsequent K+ secretion by principal cells.
C) Antagonism of the Aldosterone receptor; preventing the synthesis of ROMK channels.
D) Inhibition of Carbonic Anhydrase; leading to metabolic acidosis and compensatory K+
excretion.
Correct Answer: B) Inhibition of the Na+/K+/2Cl- cotransporter; causing increased Na+
delivery to the distal tubule and subsequent K+ secretion by principal cells.
Practice Questions & Detailed Explanations
Subject: Human Physiology
Subtopic: Neurophysiology, Cardiovascular Dynamics, and Renal Homeostasis
Question 1: A patient presents with a specific neurological deficit where they can comprehend
language but cannot produce coherent speech, despite having intact vocal cords and motor
control of the articulatory muscles. If this is due to an ischemic stroke, which specific cortical
area is most likely affected, and what is the functional result of this lesion?
A) Wernicke’s area; resulting in fluent aphasia where the patient produces meaningless, rapid
speech.
B) Broca’s area; resulting in non-fluent, expressive aphasia where the patient struggles to form
grammatical sentences.
C) Primary motor cortex; resulting in dysarthria due to paralysis of the tongue and laryngeal
muscles.
D) Arcuate fasciculus; resulting in conduction aphasia, characterized by the inability to repeat
spoken words.
Correct Answer: B) Broca’s area; resulting in non-fluent, expressive aphasia where the
patient struggles to form grammatical sentences.
Explanation: Broca’s area, located in the posterior inferior frontal gyrus of the dominant
hemisphere, is responsible for motor speech planning. Lesions here cause expressive aphasia,
where comprehension remains intact, but speech output is labored and telegraphic. Option A
describes Wernicke’s aphasia, where comprehension is impaired. Option C refers to a motor
execution deficit (dysarthria) rather than a language processing deficit. Option D refers to the
fiber tract connecting the two, causing failure to repeat, which is a different clinical syndrome.
Question 2: During an action potential in a large myelinated axon, which of the following best
describes the physiological basis for the "absolute refractory period"?
A) Continued activity of the Na+/K+ ATPase pump attempting to restore resting membrane
potential.
B) The delayed opening of voltage-gated potassium channels causing hyperpolarization.
C) The inactivation state of voltage-gated sodium channels that cannot be opened regardless of
stimulus strength.
,D) The increased chloride conductance leading to an inhibitory postsynaptic potential.
Correct Answer: C) The inactivation state of voltage-gated sodium channels that cannot be
opened regardless of stimulus strength.
Explanation: The absolute refractory period is strictly defined by the time during which voltage-
gated sodium channels are in their inactivated state. Even a suprathreshold stimulus cannot
elicit another action potential because the inactivation gate "plugs" the channel. Option B
describes the mechanism for the relative refractory period (hyperpolarization). Option A is a
continuous maintenance process, not the primary cause of the refractory period.
Question 3: Which of the following hemodynamic changes would most significantly increase
the myocardial oxygen demand of a patient with stable angina?
A) A decrease in left ventricular end-diastolic volume.
B) An increase in heart rate.
C) An increase in diastolic filling time.
D) A decrease in left ventricular wall thickness.
Correct Answer: B) An increase in heart rate.
Explanation: Myocardial oxygen demand is primarily determined by heart rate, wall tension
(Law of Laplace), and contractility. Heart rate is a dominant factor because it increases the
metabolic rate of the heart while simultaneously reducing the time available for coronary
perfusion (which occurs during diastole). Options A and C would generally decrease oxygen
demand, and D would decrease wall tension, thus decreasing demand.
Question 4: In a patient experiencing a significant reduction in glomerular filtration rate (GFR)
due to renal artery stenosis, which mechanism is primarily responsible for the compensatory
maintenance of GFR?
A) Afferent arteriolar vasoconstriction via the sympathetic nervous system.
B) Efferent arteriolar vasoconstriction mediated by Angiotensin II.
C) Vasodilation of the afferent arteriole by Prostaglandins.
D) Increased release of Atrial Natriuretic Peptide (ANP).
Correct Answer: B) Efferent arteriolar vasoconstriction mediated by Angiotensin II.
Explanation: Renal artery stenosis leads to decreased renal perfusion pressure, triggering the
Renin-Angiotensin-Aldosterone System (RAAS). Angiotensin II preferentially constricts the
, efferent arteriole, which increases the hydrostatic pressure in the glomerular capillaries, thereby
maintaining GFR despite low inflow. Option A would decrease GFR. Option C is a protective
mechanism for flow, but the direct hormonal regulation of pressure to maintain GFR is primarily
efferent control.
Question 5: A patient shows hyperkalemia with EKG changes. Which shift in the tubular
handling of potassium is the most likely physiological consequence of the body’s attempt to
manage this electrolyte imbalance via the distal convoluted tubule?
A) Increased activity of the Na+/K+/2Cl- symporter.
B) Decreased secretion of aldosterone by the adrenal cortex.
C) Increased activity of the ENaC (epithelial sodium channels) and ROMK (renal outer
medullary potassium) channels.
D) Inhibition of the H+/K+ ATPase in the intercalated cells.
Correct Answer: C) Increased activity of the ENaC (epithelial sodium channels) and ROMK
(renal outer medullary potassium) channels.
Explanation: Hyperkalemia directly stimulates the release of aldosterone. Aldosterone acts on
the principal cells of the collecting duct to increase the expression of ENaC (to reabsorb Na+)
and ROMK channels (to secrete K+). This process promotes potassium excretion to lower
plasma levels. Options A and D do not represent the primary mechanism for renal potassium
regulation in this context.
6. Renal Physiology & Cardiovascular Integration
Question 6: A patient with chronic hypertension presents with edema. A diuretic that acts on the
thick ascending limb of the loop of Henle is administered. What is the molecular mechanism of
this drug, and why might it cause hypokalemia?
A) Inhibition of the Na+/Cl- symporter; causing excessive Na+ delivery to the distal tubule.
B) Inhibition of the Na+/K+/2Cl- cotransporter; causing increased Na+ delivery to the distal
tubule and subsequent K+ secretion by principal cells.
C) Antagonism of the Aldosterone receptor; preventing the synthesis of ROMK channels.
D) Inhibition of Carbonic Anhydrase; leading to metabolic acidosis and compensatory K+
excretion.
Correct Answer: B) Inhibition of the Na+/K+/2Cl- cotransporter; causing increased Na+
delivery to the distal tubule and subsequent K+ secretion by principal cells.
