NBRC Cardiopulmonary Anatomy and Physiology 1 — Questions and Answers
Question 1: Which of the following best describes the primary function of the alveoli?
- Gas exchange between air and blood (Correct answer)
- Warming and humidifying inspired air
- Filtering particulates from inhaled air
- Producing surfactant only
Correct answer: Gas exchange between air and blood
Alveoli are the primary sites of gas exchange where oxygen diffuses into the blood and carbon dioxide diffuses out.
Question 2: The normal partial pressure of oxygen (PaO2) in arterial blood at sea level is approximately:
- 40 mmHg
- 60 mmHg
- 80–100 mmHg (Correct answer)
- 120 mmHg
Correct answer: 80–100 mmHg
Normal PaO2 ranges from 80 to 100 mmHg in a healthy adult breathing room air at sea level.
Question 3: Which muscle is the primary muscle of inspiration?
- Internal intercostals
- Diaphragm (Correct answer)
- Sternocleidomastoid
- Scalenes
Correct answer: Diaphragm
The diaphragm contracts and flattens during inspiration, generating the pressure gradient that draws air into the lungs.
Question 4: What is the Bohr effect?
- Increased CO2 shifts the oxyhemoglobin curve left
- Increased CO2 shifts the oxyhemoglobin curve right (Correct answer)
- Decreased temperature shifts the curve right
- Increased pH shifts the curve right
Correct answer: Increased CO2 shifts the oxyhemoglobin curve right
The Bohr effect describes how elevated CO2 (and decreased pH) reduces hemoglobin's affinity for oxygen, shifting the oxyhemoglobin dissociation curve to the right.
Question 5: Which lung zone, according to the West zones model, has the greatest blood flow?
- Zone 1 (apex)
- Zone 2 (mid-lung)
- Zone 3 (base) (Correct answer)
- Zone 4 (extreme base)
Correct answer: Zone 3 (base)
Zone 3 (base) has the greatest blood flow because both arterial and venous pressures exceed alveolar pressure, keeping pulmonary capillaries continuously open.
Question 6: Normal cardiac output at rest is approximately:
- 1–2 L/min
- 3–4 L/min
- 5–6 L/min (Correct answer)
- 8–10 L/min
Correct answer: 5–6 L/min
Resting cardiac output is typically 5–6 L/min, calculated as heart rate multiplied by stroke volume.
NBRC Cardiopulmonary Anatomy and Physiology 1
Which of the following best describes the primary function of the alveoli?