W3 - Alveoli

Alveoli

• ~300 million alveoli total surface area is 150m²

• dense capillary supply

• site of gas exchange

• thin barrier for gas exchange

Structure of alveoli

• formed from squamous type I alveolar epithelial cells → comprise of the respiratory membrane where they contract surrounding capillaries

• scattered type II cells - secrete surfactant (prevents alveolar collapse)

• alveolar macrophages monitor internal alveolar surfaces

respiratory membrane

• thin air-blood barrier (0.5um wide)

• liquid coating (prevents dehydration)

• composed of:

  • single layer of squamous alveolar epithelium (type I cells)

  • fused basement membrane

  • pulmonary capillary (endothelial cells)

• site of gas exchange (via simple diffusion)

N/A

N/A