Tiny sacs within the lungs which increase respiratory surface?

The tiny sacs within the lungs that increase the respiratory surface are called alveoli. Alveoli are small, balloon-shaped structures located at the end of the respiratory bronchioles in the lungs. They form the primary site for gas exchange between the air and the bloodstream. The walls of the alveoli are extremely thin, allowing for the efficient diffusion of oxygen and carbon dioxide between the air and the blood.

Alveoli are lined with a layer of specialized cells called type I and type II pneumocytes. Type I pneumocytes are thin, squamous cells that allow for the diffusion of gases. Type II pneumocytes are responsible for the production of surfactant, a substance that reduces the surface tension at the air-liquid interface within the alveoli, preventing them from collapsing.

The extensive network of alveoli in the lungs significantly increases the respiratory surface area, which facilitates efficient gas exchange. The large number of alveoli, estimated to be around 300-400 million per lung, maximizes the contact between the air and the bloodstream, allowing for the rapid uptake of oxygen and the release of carbon dioxide.