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
1. A student asks why the trachea is reinforced with C-shaped cartilage rings. What is the best
physiological explanation for this structure?
A. To prevent collapse during inspiration (keeping the airway open).
B. To allow for expansion of the esophagus during swallowing.
C. To filter out dust particles before they reach the bronchi.
D. To secrete mucus to trap pathogens.
Answer: A
Rationale: The primary function of the cartilage rings is to maintain a patent (open) airway.
During inspiration, intrathoracic pressure drops, which could cause a soft tube to collapse. The
rigidity of the rings prevents this. The open posterior part of the "C" (B) does allow the
esophagus to expand when food passes, but the primary reason for the reinforcement is airway
patency.
2. Which of the following cell types is responsible for secreting the pulmonary surfactant that
reduces surface tension in the alveoli?
A. Type I alveolar cells
B. Type II alveolar cells
C. Alveolar macrophages
D. Goblet cells
Answer: B
,Rationale: Type I alveolar cells (A) are the thin squamous cells where gas exchange actually
occurs. Type II alveolar cells (B) are cuboidal cells that secrete surfactant. Macrophages (C) are
immune cells ("dust cells"), and goblet cells (D) are found in the conducting zone
(trachea/bronchi), not the alveoli.
3. [Mandatory] A patient is diagnosed with Infant Respiratory Distress Syndrome (IRDS). The
nurse explains that the lack of surfactant leads to alveolar collapse. Which physical property is
primarily responsible for this collapse if surfactant is absent?
A. High compliance
B. High surface tension
C. Low elasticity
D. High atmospheric pressure
Answer: B
Rationale: Water molecules lining the alveoli have a strong attraction for one another (cohesion).
This force creates surface tension, which constantly tries to pull the alveoli inward to the smallest
possible size (collapse). Surfactant interrupts this attraction, lowering surface tension. Without it,
high surface tension makes the alveoli extremely stiff and prone to collapse (atelectasis).
4. During forced expiration, such as when blowing out candles, which of the following muscles
is actively contracted?
A. Diaphragm
B. External intercostals
C. Internal intercostals and abdominal muscles
D. Sternocleidomastoid
Answer: C
Rationale: Quiet expiration is passive, relying on elastic recoil. However, forced expiration
requires active contraction to push more air out. The internal intercostals (which pull ribs
down/in) and the abdominal muscles (which compress the abdominal cavity, pushing the
diaphragm up) are recruited for this. The diaphragm (A) and external intercostals (B) are
inspiratory muscles.
, 5. The movement of air into and out of the lungs is driven by differences in pressure between the
atmosphere and the alveoli. According to Boyle’s Law, which relationship is correct?
A. Pressure is directly proportional to volume.
B. Pressure is inversely proportional to volume.
C. Volume is constant regardless of pressure.
D. Pressure is unrelated to volume changes in the thorax.
Answer: B
Rationale: Boyle’s Law states that at a constant temperature, the pressure of a gas is inversely
proportional to its volume. As the thoracic volume increases (diaphragm contracts), the pressure
inside the lungs decreases below atmospheric pressure, and air rushes in.
6. If a patient has a lung condition that decreases lung compliance, the nurse would expect:
A. The lungs to be very easy to inflate.
B. The lungs to be stiff and difficult to expand.
C. A decrease in the work of breathing.
D. An increase in the vital capacity.
Answer: B
Rationale: Compliance refers to the ability of the lungs to stretch and expand. Low compliance
(stiffness) means a greater change in pressure is required to achieve the same volume of air. This
makes breathing harder (increased work of breathing). Fibrosis is a classic cause of low
compliance.
with Lab Latest update 2026/2027 | Chamberlain |
Q&A with Rationales | Grade A | Pass Guaranteed
A+ Graded
1. A student asks why the trachea is reinforced with C-shaped cartilage rings. What is the best
physiological explanation for this structure?
A. To prevent collapse during inspiration (keeping the airway open).
B. To allow for expansion of the esophagus during swallowing.
C. To filter out dust particles before they reach the bronchi.
D. To secrete mucus to trap pathogens.
Answer: A
Rationale: The primary function of the cartilage rings is to maintain a patent (open) airway.
During inspiration, intrathoracic pressure drops, which could cause a soft tube to collapse. The
rigidity of the rings prevents this. The open posterior part of the "C" (B) does allow the
esophagus to expand when food passes, but the primary reason for the reinforcement is airway
patency.
2. Which of the following cell types is responsible for secreting the pulmonary surfactant that
reduces surface tension in the alveoli?
A. Type I alveolar cells
B. Type II alveolar cells
C. Alveolar macrophages
D. Goblet cells
Answer: B
,Rationale: Type I alveolar cells (A) are the thin squamous cells where gas exchange actually
occurs. Type II alveolar cells (B) are cuboidal cells that secrete surfactant. Macrophages (C) are
immune cells ("dust cells"), and goblet cells (D) are found in the conducting zone
(trachea/bronchi), not the alveoli.
3. [Mandatory] A patient is diagnosed with Infant Respiratory Distress Syndrome (IRDS). The
nurse explains that the lack of surfactant leads to alveolar collapse. Which physical property is
primarily responsible for this collapse if surfactant is absent?
A. High compliance
B. High surface tension
C. Low elasticity
D. High atmospheric pressure
Answer: B
Rationale: Water molecules lining the alveoli have a strong attraction for one another (cohesion).
This force creates surface tension, which constantly tries to pull the alveoli inward to the smallest
possible size (collapse). Surfactant interrupts this attraction, lowering surface tension. Without it,
high surface tension makes the alveoli extremely stiff and prone to collapse (atelectasis).
4. During forced expiration, such as when blowing out candles, which of the following muscles
is actively contracted?
A. Diaphragm
B. External intercostals
C. Internal intercostals and abdominal muscles
D. Sternocleidomastoid
Answer: C
Rationale: Quiet expiration is passive, relying on elastic recoil. However, forced expiration
requires active contraction to push more air out. The internal intercostals (which pull ribs
down/in) and the abdominal muscles (which compress the abdominal cavity, pushing the
diaphragm up) are recruited for this. The diaphragm (A) and external intercostals (B) are
inspiratory muscles.
, 5. The movement of air into and out of the lungs is driven by differences in pressure between the
atmosphere and the alveoli. According to Boyle’s Law, which relationship is correct?
A. Pressure is directly proportional to volume.
B. Pressure is inversely proportional to volume.
C. Volume is constant regardless of pressure.
D. Pressure is unrelated to volume changes in the thorax.
Answer: B
Rationale: Boyle’s Law states that at a constant temperature, the pressure of a gas is inversely
proportional to its volume. As the thoracic volume increases (diaphragm contracts), the pressure
inside the lungs decreases below atmospheric pressure, and air rushes in.
6. If a patient has a lung condition that decreases lung compliance, the nurse would expect:
A. The lungs to be very easy to inflate.
B. The lungs to be stiff and difficult to expand.
C. A decrease in the work of breathing.
D. An increase in the vital capacity.
Answer: B
Rationale: Compliance refers to the ability of the lungs to stretch and expand. Low compliance
(stiffness) means a greater change in pressure is required to achieve the same volume of air. This
makes breathing harder (increased work of breathing). Fibrosis is a classic cause of low
compliance.
