Example 1 · difficulty 1/5
The human trachea is held open by C-shaped cartilaginous rings that are incomplete dorsally. The most appropriate reason for this incomplete (C-shaped) arrangement is that it:
- A. allows the ciliated epithelium to beat freely over the entire circumference
- B. permits the trachea to collapse completely during forced expiration
- C. keeps the airway patent while allowing the adjacent oesophagus to bulge during swallowing
- D. enables the rings to secrete surfactant that lowers surface tension