WGU D313 Anatomy and Physiology II
Objective Assessment Exam
2026/2027 Newly Released
70 Verified Questions with answers and expert rationales
Q1: Which layer of the heart is the thickest and composed primarily of cardiac muscle tissue
responsible for the heart's pumping action?
A. Myocardium
B. Epicardium
C. Endocardium
D. Pericardium
Correct Answer: A
Rationale: Correct because the myocardium is the middle layer of the heart wall composed of
cardiac muscle tissue, which generates the contractile force necessary to pump blood through
the circulatory system. The thickness of the myocardium is greatest in the left ventricle, allowing
it to generate enough pressure to overcome systemic vascular resistance.
Q2: A patient has a blood pH of 7.30, a PaCO2 of 55 mm Hg, and HCO3– of 24 mEq/L. Based on
these values, which acid-base disorder is present?
A. Metabolic acidosis
B. Respiratory acidosis
C. Metabolic alkalosis
D. Respiratory alkalosis
Correct Answer: B
,Rationale: Correct because the low pH indicates acidosis, and the elevated PaCO2 identifies the
cause as respiratory failure to eliminate carbon dioxide. Since the HCO3– is within the normal
range, there is no metabolic compensation occurring yet, distinguishing it from a metabolic
disorder.
Q3: Which hormone is released by the posterior pituitary gland and acts on the kidneys to
increase water reabsorption, thereby concentrating urine?
A. Aldosterone
B. Oxytocin
C. Antidiuretic hormone (ADH)
D. Atrial natriuretic peptide (ANP)
Correct Answer: C
Rationale: Correct because antidiuretic hormone (ADH) causes the insertion of aquaporin
channels into the collecting ducts of the nephron, increasing the permeability of the membrane
to water. This allows water to move passively out of the tubule and back into the blood,
resulting in reduced urine volume and concentrated urine.
Q4: Which structure connects the atria to the ventricles and consists of modified cardiac muscle
cells that delay the electrical impulse to allow the atria to finish contracting?
A. Sinoatrial (SA) node
B. Bundle of His
C. Atrioventricular (AV) node
D. Purkinje fibers
Correct Answer: C
Rationale: Correct because the AV node is the only electrical connection between the atria and
ventricles; its slow conduction velocity creates a critical delay. This delay ensures that the atria
have fully emptied their blood into the ventricles before the ventricles begin to contract.
, Q5: During the systemic circulation, a drop of blood travels from the left ventricle to the big toe
and back to the heart. What is the correct sequence of blood vessels through which it passes
during the return trip?
A. Aorta → arterioles → capillaries → venules → veins → inferior vena cava → right atrium
B. Aorta → capillaries → arterioles → veins → venules → superior vena cava → right atrium
C. Left ventricle → left atrium → aorta → veins → right ventricle
D. Aorta → aorta → capillaries → veins → pulmonary artery → right atrium
Correct Answer: A
Rationale: Correct because blood exits the heart via the aorta, travels through smaller arteries
and arterioles to reach capillary beds for exchange, then returns via venules and veins. Finally,
the deoxygenated blood is delivered to the right atrium via the superior or inferior vena cava to
re-enter pulmonary circulation.
Q6: Which type of immunity is provided by a mother to her fetus via the placenta, where pre-
formed antibodies cross the placental barrier?
A. Active natural immunity
B. Passive natural immunity
C. Active artificial immunity
D. Passive artificial immunity
Correct Answer: B
Rationale: Correct because passive immunity involves receiving pre-made antibodies from an
outside source rather than producing them oneself. In this case, the naturally occurring transfer
of maternal IgG across the placenta provides the fetus with immediate, but temporary,
protection against pathogens.
Objective Assessment Exam
2026/2027 Newly Released
70 Verified Questions with answers and expert rationales
Q1: Which layer of the heart is the thickest and composed primarily of cardiac muscle tissue
responsible for the heart's pumping action?
A. Myocardium
B. Epicardium
C. Endocardium
D. Pericardium
Correct Answer: A
Rationale: Correct because the myocardium is the middle layer of the heart wall composed of
cardiac muscle tissue, which generates the contractile force necessary to pump blood through
the circulatory system. The thickness of the myocardium is greatest in the left ventricle, allowing
it to generate enough pressure to overcome systemic vascular resistance.
Q2: A patient has a blood pH of 7.30, a PaCO2 of 55 mm Hg, and HCO3– of 24 mEq/L. Based on
these values, which acid-base disorder is present?
A. Metabolic acidosis
B. Respiratory acidosis
C. Metabolic alkalosis
D. Respiratory alkalosis
Correct Answer: B
,Rationale: Correct because the low pH indicates acidosis, and the elevated PaCO2 identifies the
cause as respiratory failure to eliminate carbon dioxide. Since the HCO3– is within the normal
range, there is no metabolic compensation occurring yet, distinguishing it from a metabolic
disorder.
Q3: Which hormone is released by the posterior pituitary gland and acts on the kidneys to
increase water reabsorption, thereby concentrating urine?
A. Aldosterone
B. Oxytocin
C. Antidiuretic hormone (ADH)
D. Atrial natriuretic peptide (ANP)
Correct Answer: C
Rationale: Correct because antidiuretic hormone (ADH) causes the insertion of aquaporin
channels into the collecting ducts of the nephron, increasing the permeability of the membrane
to water. This allows water to move passively out of the tubule and back into the blood,
resulting in reduced urine volume and concentrated urine.
Q4: Which structure connects the atria to the ventricles and consists of modified cardiac muscle
cells that delay the electrical impulse to allow the atria to finish contracting?
A. Sinoatrial (SA) node
B. Bundle of His
C. Atrioventricular (AV) node
D. Purkinje fibers
Correct Answer: C
Rationale: Correct because the AV node is the only electrical connection between the atria and
ventricles; its slow conduction velocity creates a critical delay. This delay ensures that the atria
have fully emptied their blood into the ventricles before the ventricles begin to contract.
, Q5: During the systemic circulation, a drop of blood travels from the left ventricle to the big toe
and back to the heart. What is the correct sequence of blood vessels through which it passes
during the return trip?
A. Aorta → arterioles → capillaries → venules → veins → inferior vena cava → right atrium
B. Aorta → capillaries → arterioles → veins → venules → superior vena cava → right atrium
C. Left ventricle → left atrium → aorta → veins → right ventricle
D. Aorta → aorta → capillaries → veins → pulmonary artery → right atrium
Correct Answer: A
Rationale: Correct because blood exits the heart via the aorta, travels through smaller arteries
and arterioles to reach capillary beds for exchange, then returns via venules and veins. Finally,
the deoxygenated blood is delivered to the right atrium via the superior or inferior vena cava to
re-enter pulmonary circulation.
Q6: Which type of immunity is provided by a mother to her fetus via the placenta, where pre-
formed antibodies cross the placental barrier?
A. Active natural immunity
B. Passive natural immunity
C. Active artificial immunity
D. Passive artificial immunity
Correct Answer: B
Rationale: Correct because passive immunity involves receiving pre-made antibodies from an
outside source rather than producing them oneself. In this case, the naturally occurring transfer
of maternal IgG across the placenta provides the fetus with immediate, but temporary,
protection against pathogens.
