The pulmonary alveoli are small sacs found in the lungs, where gas exchange takes places.
Some of their features are:
• They are found in the respiratory bronchioles.
,• They are cup-shaped cavities
,• The gas exchange happens by diffusion in the alveolar membrane.
,• They consist of an epithelial layer and an extracellular matrix surrounded by capillaries.
• They are found only in mammalian lungs
,• They can stretch during inhalation thanks to collagen fibers.
,• In humans, they are functional at 32 weeks of gestation, but they continue to develop until puberty.
