What are the tiny air sacs within the lungs that facilitate gas exchange called?

The tiny air sacs within the lungs that facilitate gas exchange are called alveoli. These structures are essential for respiration as they provide a large surface area for the exchange of oxygen and carbon dioxide between the air in the lungs and the blood in the capillaries. Each alveolus is surrounded by a network of capillaries, allowing for efficient transfer of gases; oxygen from the air enters the blood, while carbon dioxide from the blood is exhaled. This gas exchange process is crucial for maintaining the body's oxygen supply and for removing waste gases, making alveoli a vital component of the respiratory system.

In contrast, bronchi refer to the larger air passages that lead from the trachea to the lungs, bronchioles are the smaller branches that come off the bronchi, and pleura are the membranes surrounding the lungs. These structures play important roles in the respiratory system, but they do not directly facilitate gas exchange like alveoli do.