GENERAL HISTOLOGY

Detailed explanation-1: -Each alveolus is cup-shaped with very thin walls. It’s surrounded by networks of blood vessels called capillaries that also have thin walls. The oxygen you breathe in diffuses through the alveoli and the capillaries into the blood.

Detailed explanation-2: -The alveoli are surrounded by the alveolar-capillary membrane, which normally prevents liquid in the capillaries from entering the air sacs.

Detailed explanation-3: -An alveolus consists of an epithelial layer of simple squamous epithelium (very thin, flattened cells), and an extracellular matrix surrounded by capillaries. The epithelial lining is part of the alveolar membrane, also known as the respiratory membrane, that allows the exchange of gases.

Detailed explanation-4: -Pneumocytes (Type I cells) They have long cytoplasmic extensions that cover beyond 95% of the alveolar surface. The thin lining enables a fast diffusion of gas exchange between the air in the alveoli and the blood in the surrounding capillaries.