What is the primary function of alveoli in the lungs?

• A. To produce mucus for respiratory moisture
• B. To serve as the site for oxygen and carbon dioxide exchange
• C. To connect bronchi to the trachea
• D. To filter dust and allergens from inhaled air

Answer: (B)

The primary function of alveoli in the lungs is to serve as the site for oxygen and carbon dioxide exchange. Alveoli are tiny, balloon-like structures located at the end of the respiratory tree where the gas exchange occurs. They are surrounded by a network of capillaries, which allows oxygen from the inhaled air to diffuse into the blood and carbon dioxide from the blood to be exhaled. This exchange is crucial for maintaining the body’s oxygen levels and removing waste gases, facilitating respiration at a cellular level.

Mucus production, connection of bronchi to the trachea, and filtering dust and allergens are important processes in the respiratory system, but they are not the primary roles of the alveoli. Mucus is produced by specialized cells in the respiratory tract to keep the airways moist and trap particles. Connection of bronchi to the trachea pertains to the structure of the respiratory system, while the filtering of dust and allergens is primarily the responsibility of the nasal passages and upper respiratory structures. Alveoli focus specifically on the critical function of gas exchange, making them essential for respiration.