Which structure is responsible for gas exchange in the lungs?

Which structure is responsible for gas exchange in the lungs?

• A. The bronchi
• B. The alveoli
• C. The trachea
• D. The diaphragm

Answer: (B)

The alveoli are the structures in the lungs responsible for gas exchange. These tiny, balloon-like sacs are designed to maximize surface area for the exchange of oxygen and carbon dioxide between the air and the bloodstream. When air is inhaled, it travels through the bronchi and into the alveoli, where oxygen from the air passes through the thin walls of the alveoli into the capillaries. Simultaneously, carbon dioxide, which is a waste product of metabolism, diffuses from the blood into the alveoli to be exhaled. This specialized structure is essential for efficient respiration because the alveoli have a large surface area and are surrounded by a dense network of capillaries, which facilitates the rapid exchange of gases. The mechanics of breathing, involving the diaphragm and other muscles, help to move air in and out of the lungs but do not partake in the process of gas exchange itself. Understanding the role of the alveoli clarifies their critical function in the respiratory system and highlights why they are the key site for gas exchange.

The alveoli are the structures in the lungs responsible for gas exchange. These tiny, balloon-like sacs are designed to maximize surface area for the exchange of oxygen and carbon dioxide between the air and the bloodstream. When air is inhaled, it travels through the bronchi and into the alveoli, where oxygen from the air passes through the thin walls of the alveoli into the capillaries. Simultaneously, carbon dioxide, which is a waste product of metabolism, diffuses from the blood into the alveoli to be exhaled.

This specialized structure is essential for efficient respiration because the alveoli have a large surface area and are surrounded by a dense network of capillaries, which facilitates the rapid exchange of gases. The mechanics of breathing, involving the diaphragm and other muscles, help to move air in and out of the lungs but do not partake in the process of gas exchange itself.

Understanding the role of the alveoli clarifies their critical function in the respiratory system and highlights why they are the key site for gas exchange.