The Structure of Alveoli and their role in Gas Exchange including the role and function of Surfactants.

... The Structure of Alveoli and their role in Gas Exchange including the role and function of Surfactants Introduction Alveoli are found within the lungs. The trachea splits into 2 bronchi, which in turn split into multiple bronchioles. These in turn branch into finer and finer tubes, ending with the alveolar ducts, which terminate in alveolar sacs which are surrounded by clusters of alveoli. The alveolar wall is composed of two types of cell. Type I is involved in the diffusion of respiratory gases. Type II is involved in the production of surfactant. Into each alveolar sac opens a group of alveoli. Alveoli are shaped as tiny 'balloon-like' cells, to allow for efficient gas exchange and relatively easy inflation/deflation. The alveoli act as a specialised gaseous exchange surface in mammals, and therefore require constant access to the blood stream and air. This gas exchange occurs by the diffusion across type I

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