Which condition is characterized by alveoli collapse, reducing gas exchange?

Which condition is characterized by alveoli collapse, reducing gas exchange?

• A. Emphysema
• B. Pneumothorax
• C. Atelectasis
• D. Bronchitis

Answer: (C)

The main idea is that gas exchange depends on open, functioning alveoli where oxygen can diffuse into the blood and carbon dioxide can be expelled. When the alveoli collapse or fail to inflate, the surface area available for diffusion drops dramatically and some lung regions become nonventilated. That loss of ventilation in those regions creates a mismatch with perfusion and overall oxygenation falls because less oxygen reaches the blood and less CO2 is released. This specific condition is atelectasis, the collapse or incomplete expansion of alveoli. It can happen from a blocked airway, shallow breathing after surgery, or external pressure compressing part of the lung. Emphysema reduces gas exchange too, but through destruction of the small air sacs and loss of elastic recoil, not by alveolar collapse. A pneumothorax causes the lung to collapse because air enters the pleural space and the lung volume is lost, not mainly because alveoli collapse. Bronchitis inflames the airways with mucus, hindering airflow, but the alveoli themselves usually remain open.

The main idea is that gas exchange depends on open, functioning alveoli where oxygen can diffuse into the blood and carbon dioxide can be expelled. When the alveoli collapse or fail to inflate, the surface area available for diffusion drops dramatically and some lung regions become nonventilated. That loss of ventilation in those regions creates a mismatch with perfusion and overall oxygenation falls because less oxygen reaches the blood and less CO2 is released.

This specific condition is atelectasis, the collapse or incomplete expansion of alveoli. It can happen from a blocked airway, shallow breathing after surgery, or external pressure compressing part of the lung.

Emphysema reduces gas exchange too, but through destruction of the small air sacs and loss of elastic recoil, not by alveolar collapse. A pneumothorax causes the lung to collapse because air enters the pleural space and the lung volume is lost, not mainly because alveoli collapse. Bronchitis inflames the airways with mucus, hindering airflow, but the alveoli themselves usually remain open.