BIOS 255 / BIOS255 Exam 2: Anatomy & Physiology III
with Lab Latest update 2026/2027 | Chamberlain |
Q&A with Rationales | Grade A | Pass Guaranteed
A+ Graded
Q1: Which structure of the upper respiratory tract is lined with stratified squamous epithelium
and serves as the common passageway for both air and food?
A. Nasopharynx
B. Oropharynx [CORRECT]
C. Laryngopharynx
D. Trachea
Correct Answer: B
Rationale: Correct because the oropharynx lies posterior to the oral cavity and extends
down to the epiglottis. Unlike the nasopharynx (pseudostratified ciliated columnar), the
oropharynx is subjected to abrasion from food, so it is lined with non-keratinized stratified
squamous epithelium. It serves as a common pathway for air and food.
Q2: A premature infant is born with insufficient surfactant production. Which of the following
physiological consequences is most likely to occur?
A. Increased lung compliance and alveolar collapse
B. Decreased surface tension and alveolar overdistension
C. Increased work of breathing due to high surface tension and alveolar collapse (atelectasis)
[CORRECT]
D. Immediate development of chronic bronchitis
Correct Answer: C
Rationale: Correct because surfactant reduces surface tension within the alveoli. Without
it, surface tension is high, causing small alveoli to collapse (atelectasis) according to the
Law of Laplace. The infant must generate much higher negative pressure to reinflate the
lungs, drastically increasing the work of breathing, leading to Infant Respiratory Distress
Syndrome (IRDS).
,Q3: During quiet inspiration, the diaphragm contracts and moves:
A. Superiorly, decreasing thoracic volume
B. Inferiorly, increasing thoracic volume [CORRECT]
C. Laterally, decreasing intrapleural pressure
D. Anteriorly, compressing the abdominal organs
Correct Answer: B
Rationale: Correct because the diaphragm is a dome-shaped muscle. When it contracts, it
flattens and moves inferiorly toward the abdominal cavity. This increases the vertical
dimension of the thoracic cavity, which decreases intrapleural pressure and draws air into
the lungs.
Q4: Which of the following represents the correct partial pressure gradient for oxygen diffusion
from the alveoli into the pulmonary capillary blood?
A. Alveolar PO2 (104 mmHg) → Capillary PO2 (40 mmHg) [CORRECT]
B. Alveolar PO2 (40 mmHg) → Capillary PO2 (104 mmHg)
C. Alveolar PO2 (45 mmHg) → Capillary PO2 (40 mmHg)
D. Alveolar PO2 (104 mmHg) → Capillary PO2 (100 mmHg)
Correct Answer: A
Rationale: Correct because gas diffusion follows the pressure gradient from high to low
pressure. The partial pressure of oxygen (PO2) in the alveoli is approximately 104 mmHg,
while the PO2 in the deoxygenated blood entering the pulmonary capillaries is about 40
mmHg. This steep gradient drives O2 into the blood.
Q5: Select all that apply: Which of the following factors will shift the oxyhemoglobin
dissociation curve to the RIGHT (decreasing hemoglobin's affinity for O2)?
A. Decreased temperature
B. Increased pH (alkalosis)
C. Increased 2,3-DPG [CORRECT]
D. Increased PCO2 [CORRECT]
E. Decreased hydrogen ion concentration
Correct Answer: C, D
Rationale: Correct because a right shift facilitates oxygen unloading at the tissues. Factors
causing a right shift include increased temperature, decreased pH (acidosis), increased
PCO2 (Bohr effect), and increased 2,3-diphosphoglycerate (2,3-DPG), a byproduct of RBC
glycolysis. Decreased temperature and increased pH cause a left shift (increased affinity).
, Q6: In the transport of carbon dioxide, approximately 70% is carried in the blood as:
A. Dissolved CO2 in plasma
B. Carbaminohemoglobin bound to globin
C. Bicarbonate ions (HCO3-) in plasma [CORRECT]
D. Carbonic acid in red blood cells
Correct Answer: C
Rationale: Correct because the majority of CO2 (about 70%) is converted to bicarbonate
ions inside red blood cells via the enzyme carbonic anhydrase. The bicarbonate then
diffuses out into the plasma in exchange for chloride ions (chloride shift) to be transported
to the lungs.
Q7: A patient presents with metabolic acidosis. Which of the following compensatory
mechanisms would you expect the respiratory system to initiate?
A. Hypoventilation to retain CO2
B. Hyperventilation to blow off CO2 [CORRECT]
C. Increased reabsorption of bicarbonate by the kidneys
D. Decreased respiratory rate to increase pH
Correct Answer: B
Rationale: Correct because in metabolic acidosis (low pH due to non-respiratory causes),
the respiratory center is stimulated to increase ventilation. Blowing off CO2 (an acid)
reduces the carbonic acid concentration in the blood, raising the pH back toward normal.
This is respiratory compensation.
Q8: The Hering-Breuer reflex is primarily involved in:
A. Preventing overinflation of the lungs during inspiration [CORRECT]
B. Stimulating breathing during hypoxia
C. Regulating blood pressure in the pulmonary capillaries
D. Initiating the cough reflex
Correct Answer: A
Rationale: Correct because the Hering-Breuer reflex is a protective mechanism mediated
by stretch receptors in the bronchial walls. When the lungs are overinflated, these receptors
send signals via the vagus nerve to the medulla to inhibit inspiration and promote
expiration, preventing lung damage.
with Lab Latest update 2026/2027 | Chamberlain |
Q&A with Rationales | Grade A | Pass Guaranteed
A+ Graded
Q1: Which structure of the upper respiratory tract is lined with stratified squamous epithelium
and serves as the common passageway for both air and food?
A. Nasopharynx
B. Oropharynx [CORRECT]
C. Laryngopharynx
D. Trachea
Correct Answer: B
Rationale: Correct because the oropharynx lies posterior to the oral cavity and extends
down to the epiglottis. Unlike the nasopharynx (pseudostratified ciliated columnar), the
oropharynx is subjected to abrasion from food, so it is lined with non-keratinized stratified
squamous epithelium. It serves as a common pathway for air and food.
Q2: A premature infant is born with insufficient surfactant production. Which of the following
physiological consequences is most likely to occur?
A. Increased lung compliance and alveolar collapse
B. Decreased surface tension and alveolar overdistension
C. Increased work of breathing due to high surface tension and alveolar collapse (atelectasis)
[CORRECT]
D. Immediate development of chronic bronchitis
Correct Answer: C
Rationale: Correct because surfactant reduces surface tension within the alveoli. Without
it, surface tension is high, causing small alveoli to collapse (atelectasis) according to the
Law of Laplace. The infant must generate much higher negative pressure to reinflate the
lungs, drastically increasing the work of breathing, leading to Infant Respiratory Distress
Syndrome (IRDS).
,Q3: During quiet inspiration, the diaphragm contracts and moves:
A. Superiorly, decreasing thoracic volume
B. Inferiorly, increasing thoracic volume [CORRECT]
C. Laterally, decreasing intrapleural pressure
D. Anteriorly, compressing the abdominal organs
Correct Answer: B
Rationale: Correct because the diaphragm is a dome-shaped muscle. When it contracts, it
flattens and moves inferiorly toward the abdominal cavity. This increases the vertical
dimension of the thoracic cavity, which decreases intrapleural pressure and draws air into
the lungs.
Q4: Which of the following represents the correct partial pressure gradient for oxygen diffusion
from the alveoli into the pulmonary capillary blood?
A. Alveolar PO2 (104 mmHg) → Capillary PO2 (40 mmHg) [CORRECT]
B. Alveolar PO2 (40 mmHg) → Capillary PO2 (104 mmHg)
C. Alveolar PO2 (45 mmHg) → Capillary PO2 (40 mmHg)
D. Alveolar PO2 (104 mmHg) → Capillary PO2 (100 mmHg)
Correct Answer: A
Rationale: Correct because gas diffusion follows the pressure gradient from high to low
pressure. The partial pressure of oxygen (PO2) in the alveoli is approximately 104 mmHg,
while the PO2 in the deoxygenated blood entering the pulmonary capillaries is about 40
mmHg. This steep gradient drives O2 into the blood.
Q5: Select all that apply: Which of the following factors will shift the oxyhemoglobin
dissociation curve to the RIGHT (decreasing hemoglobin's affinity for O2)?
A. Decreased temperature
B. Increased pH (alkalosis)
C. Increased 2,3-DPG [CORRECT]
D. Increased PCO2 [CORRECT]
E. Decreased hydrogen ion concentration
Correct Answer: C, D
Rationale: Correct because a right shift facilitates oxygen unloading at the tissues. Factors
causing a right shift include increased temperature, decreased pH (acidosis), increased
PCO2 (Bohr effect), and increased 2,3-diphosphoglycerate (2,3-DPG), a byproduct of RBC
glycolysis. Decreased temperature and increased pH cause a left shift (increased affinity).
, Q6: In the transport of carbon dioxide, approximately 70% is carried in the blood as:
A. Dissolved CO2 in plasma
B. Carbaminohemoglobin bound to globin
C. Bicarbonate ions (HCO3-) in plasma [CORRECT]
D. Carbonic acid in red blood cells
Correct Answer: C
Rationale: Correct because the majority of CO2 (about 70%) is converted to bicarbonate
ions inside red blood cells via the enzyme carbonic anhydrase. The bicarbonate then
diffuses out into the plasma in exchange for chloride ions (chloride shift) to be transported
to the lungs.
Q7: A patient presents with metabolic acidosis. Which of the following compensatory
mechanisms would you expect the respiratory system to initiate?
A. Hypoventilation to retain CO2
B. Hyperventilation to blow off CO2 [CORRECT]
C. Increased reabsorption of bicarbonate by the kidneys
D. Decreased respiratory rate to increase pH
Correct Answer: B
Rationale: Correct because in metabolic acidosis (low pH due to non-respiratory causes),
the respiratory center is stimulated to increase ventilation. Blowing off CO2 (an acid)
reduces the carbonic acid concentration in the blood, raising the pH back toward normal.
This is respiratory compensation.
Q8: The Hering-Breuer reflex is primarily involved in:
A. Preventing overinflation of the lungs during inspiration [CORRECT]
B. Stimulating breathing during hypoxia
C. Regulating blood pressure in the pulmonary capillaries
D. Initiating the cough reflex
Correct Answer: A
Rationale: Correct because the Hering-Breuer reflex is a protective mechanism mediated
by stretch receptors in the bronchial walls. When the lungs are overinflated, these receptors
send signals via the vagus nerve to the medulla to inhibit inspiration and promote
expiration, preventing lung damage.
