Which structure is primarily responsible for gas exchange in the lungs?

Which structure is primarily responsible for gas exchange in the lungs?

• A. Bronchi
• B. Bronchioles
• C. Alveoli
• D. Capillaries

Answer: (C)

The primary structure responsible for gas exchange in the lungs is the alveoli. Alveoli are tiny, balloon-like sacs located at the ends of the bronchioles. They have extremely thin walls and are surrounded by a network of capillaries, which allows for the efficient transfer of gases. When air is inhaled, it travels through the bronchi and bronchioles to reach the alveoli. Here, oxygen from the inhaled air passes through the thin alveolar walls into the bloodstream, where it binds to hemoglobin in red blood cells. At the same time, carbon dioxide, a waste product of metabolism, diffuses from the blood through the capillary walls and into the alveoli, from which it can be exhaled. The structures such as bronchi and bronchioles serve as conduits for airflow but are not the sites of gas exchange. Capillaries, while critical for the transport of gases, cannot be solely considered as the location for gas exchange without the alveoli, which are the specific structures that facilitate this process. Thus, the alveoli are essential for delivering oxygen to the blood and removing carbon dioxide, making them the key component in the gas exchange mechanism in the lungs.

The primary structure responsible for gas exchange in the lungs is the alveoli. Alveoli are tiny, balloon-like sacs located at the ends of the bronchioles. They have extremely thin walls and are surrounded by a network of capillaries, which allows for the efficient transfer of gases.

When air is inhaled, it travels through the bronchi and bronchioles to reach the alveoli. Here, oxygen from the inhaled air passes through the thin alveolar walls into the bloodstream, where it binds to hemoglobin in red blood cells. At the same time, carbon dioxide, a waste product of metabolism, diffuses from the blood through the capillary walls and into the alveoli, from which it can be exhaled.

The structures such as bronchi and bronchioles serve as conduits for airflow but are not the sites of gas exchange. Capillaries, while critical for the transport of gases, cannot be solely considered as the location for gas exchange without the alveoli, which are the specific structures that facilitate this process. Thus, the alveoli are essential for delivering oxygen to the blood and removing carbon dioxide, making them the key component in the gas exchange mechanism in the lungs.