CRE Respiratory System Anatomy & Physiology 3

Question 1

Which structure prevents food from entering the larynx during swallowing?

Accepted Answer

Epiglottis

Answer

The epiglottis folds down over the laryngeal inlet during swallowing to direct food and liquid into the esophagus rather than the trachea.

Question 2

In the alveolar gas equation, if PaCO₂ is 40 mmHg and FiO₂ is 0.21 at sea level, what is the approximate PAO₂?

Accepted Answer

100 mmHg

Answer

Using the simplified alveolar gas equation: PAO₂ = (713 × 0.21) − (40/0.8) ≈ 149.7 − 50 ≈ 100 mmHg under normal conditions.

Question 3

Hypoxic pulmonary vasoconstriction (HPV) serves which primary physiological purpose?

Accepted Answer

Divert blood from poorly ventilated lung units to better-ventilated areas

Answer

HPV redirects blood flow away from hypoxic, underventilated alveoli toward better-ventilated regions, thereby optimizing ventilation-perfusion matching.

Question 4

The 'butterfly' or 'bat-wing' pattern on chest X-ray in pulmonary edema is caused by fluid accumulating primarily in the:

Accepted Answer

Perihilar interstitium and alveoli

Answer

Pulmonary edema fluid preferentially accumulates in the perihilar regions due to loose connective tissue, producing the classic butterfly shadow on X-ray.

Question 5

Which bronchopulmonary segment of the right lower lobe is most dependent in the supine position and most prone to aspiration?

Accepted Answer

Superior segment

Answer

The superior segment (S6) of the right lower lobe is the most gravity-dependent in a supine patient and thus most susceptible to aspiration pneumonia.

(CRE) Certified Respiratory Educator Practice Test

(CRE) Certified Respiratory Educator Practice Test

CRE Respiratory System Anatomy & Physiology 3