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Anatomy & Physiology II Actual Exam Test Bank
2025/2026 – Complete Q&A with Rationales,
ALREADY GRADED A+
1. A 55-year-old patient’s cardiac action potential shows a prolonged plateau
phase. Which ion movement primarily maintains the plateau phase of the
ventricular myocardial action potential?
A. Influx of Na⁺ through fast sodium channels
B. Efflux of K⁺ through delayed rectifier channels
C. Influx of Ca²⁺ through L-type calcium channels
D. Influx of Cl⁻ through chloride channels
Rationale: The plateau (phase 2) of ventricular myocyte action potentials is
sustained by L-type Ca²⁺ channels permitting calcium influx, balanced by some
K⁺ efflux. Fast Na⁺ influx produces phase 0; K⁺ efflux is more dominant in
repolarization (phase 3).
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1. Which vessel layer contains smooth muscle and is primarily responsible for
regulating vessel diameter and systemic vascular resistance?
A. Tunica adventitia (externa)
B. Tunica media
C. Tunica intima
D. Endothelium of vasa vasorum
Rationale: The tunica media is composed mainly of smooth muscle and elastic
fibers; contraction/relaxation of this layer changes vessel diameter and controls
vascular resistance. The intima is endothelial; adventitia is connective tissue.
1. During normal inspiration, the primary muscle that increases thoracic cavity
volume is:
A. Internal intercostals
B. Abdominal muscles
C. Scalenes and sternocleidomastoid (at rest)
D. Diaphragm
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Rationale: Quiet (normal) inspiration is driven primarily by contraction of the
diaphragm, which flattens and increases vertical thoracic volume. Accessory
muscles (scalenes, sternocleidomastoid) are used during forced inspiration.
1. In the renal nephron, where is the majority of filtered bicarbonate (HCO₃⁻)
reabsorbed?
A. Descending thin limb of loop of Henle
B. Proximal convoluted tubule
C. Distal convoluted tubule
D. Collecting duct principal cells
Rationale: About ~85–90% of filtered bicarbonate is reclaimed in the proximal
convoluted tubule via carbonic anhydrase–dependent processes. The loop and
distal tubule contribute less to HCO₃⁻ reclamation.
1. Which hormone secreted by the anterior pituitary directly stimulates thyroid
hormone (T3/T4) production from the thyroid gland?
A. Growth hormone (GH)
B. Prolactin (PRL)
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C. Thyroid-stimulating hormone (TSH)
D. Adrenocorticotropic hormone (ACTH)
Rationale: TSH (thyrotropin) from the anterior pituitary binds thyroid follicular
cells and increases iodide uptake, thyroglobulin proteolysis, and secretion of
T3/T4. ACTH stimulates adrenal cortex; GH and prolactin have different targets.
1. Which blood component is primarily responsible for clot formation by
converting fibrinogen to fibrin at a site of vascular injury?
A. Erythrocytes
B. Leukocytes (neutrophils)
C. Platelets (thrombocytes) initiating the coagulation cascade
D. Plasma albumin
Rationale: Platelets adhere and aggregate at injury sites and provide a surface and
factors to activate the coagulation cascade, culminating in thrombin-mediated
conversion of fibrinogen to fibrin. Erythrocytes and albumin are not central to
fibrin formation.
1. A decrease in alveolar surfactant would have which immediate effect on
lung mechanics?
Anatomy & Physiology II Actual Exam Test Bank
2025/2026 – Complete Q&A with Rationales,
ALREADY GRADED A+
1. A 55-year-old patient’s cardiac action potential shows a prolonged plateau
phase. Which ion movement primarily maintains the plateau phase of the
ventricular myocardial action potential?
A. Influx of Na⁺ through fast sodium channels
B. Efflux of K⁺ through delayed rectifier channels
C. Influx of Ca²⁺ through L-type calcium channels
D. Influx of Cl⁻ through chloride channels
Rationale: The plateau (phase 2) of ventricular myocyte action potentials is
sustained by L-type Ca²⁺ channels permitting calcium influx, balanced by some
K⁺ efflux. Fast Na⁺ influx produces phase 0; K⁺ efflux is more dominant in
repolarization (phase 3).
,2 | Page
1. Which vessel layer contains smooth muscle and is primarily responsible for
regulating vessel diameter and systemic vascular resistance?
A. Tunica adventitia (externa)
B. Tunica media
C. Tunica intima
D. Endothelium of vasa vasorum
Rationale: The tunica media is composed mainly of smooth muscle and elastic
fibers; contraction/relaxation of this layer changes vessel diameter and controls
vascular resistance. The intima is endothelial; adventitia is connective tissue.
1. During normal inspiration, the primary muscle that increases thoracic cavity
volume is:
A. Internal intercostals
B. Abdominal muscles
C. Scalenes and sternocleidomastoid (at rest)
D. Diaphragm
,3 | Page
Rationale: Quiet (normal) inspiration is driven primarily by contraction of the
diaphragm, which flattens and increases vertical thoracic volume. Accessory
muscles (scalenes, sternocleidomastoid) are used during forced inspiration.
1. In the renal nephron, where is the majority of filtered bicarbonate (HCO₃⁻)
reabsorbed?
A. Descending thin limb of loop of Henle
B. Proximal convoluted tubule
C. Distal convoluted tubule
D. Collecting duct principal cells
Rationale: About ~85–90% of filtered bicarbonate is reclaimed in the proximal
convoluted tubule via carbonic anhydrase–dependent processes. The loop and
distal tubule contribute less to HCO₃⁻ reclamation.
1. Which hormone secreted by the anterior pituitary directly stimulates thyroid
hormone (T3/T4) production from the thyroid gland?
A. Growth hormone (GH)
B. Prolactin (PRL)
, 4 | Page
C. Thyroid-stimulating hormone (TSH)
D. Adrenocorticotropic hormone (ACTH)
Rationale: TSH (thyrotropin) from the anterior pituitary binds thyroid follicular
cells and increases iodide uptake, thyroglobulin proteolysis, and secretion of
T3/T4. ACTH stimulates adrenal cortex; GH and prolactin have different targets.
1. Which blood component is primarily responsible for clot formation by
converting fibrinogen to fibrin at a site of vascular injury?
A. Erythrocytes
B. Leukocytes (neutrophils)
C. Platelets (thrombocytes) initiating the coagulation cascade
D. Plasma albumin
Rationale: Platelets adhere and aggregate at injury sites and provide a surface and
factors to activate the coagulation cascade, culminating in thrombin-mediated
conversion of fibrinogen to fibrin. Erythrocytes and albumin are not central to
fibrin formation.
1. A decrease in alveolar surfactant would have which immediate effect on
lung mechanics?
