What are the tiny sacs of lung tissue specialized for gas exchange called?

The tiny sacs of lung tissue specialized for gas exchange are called alveoli. Alveoli are small, balloon-like structures located at the end of the bronchioles in the lungs. They provide a large surface area for the exchange of oxygen and carbon dioxide between the air we breathe and the bloodstream. Each alveolus is surrounded by a network of capillaries, where the exchange occurs. The structure of alveoli facilitates efficient gas transfer due to their thin walls and extensive surface area, allowing oxygen to enter the blood and carbon dioxide to be expelled from it effectively. This is crucial for maintaining proper respiratory function and overall body homeostasis.

Other options refer to different components of the respiratory system; bronchi are the main passageways that branch off the trachea and lead to each lung, capillaries are the small blood vessels involved in the transport of gases but are not structures within the lungs, and pleurae are the membranes surrounding the lungs that help reduce friction during breathing. Each serves important functions but does not pertain directly to the site of gas exchange.