Alveolar capillary network (magnified)
Rete capillare alveolare
RespiratoryOrgansWhole bodyRight side
- What it is
- A dense mesh of pulmonary capillaries wrapped over the alveolar walls, fed by branches of the pulmonary artery.
- Function
- Brings deoxygenated blood within half a micrometre of alveolar air; each red cell crosses in about 0.75 s, time enough to load oxygen.
- Size
- Capillaries are 5–8 µm wide, just enough for red cells in single file; together they hold ~70–100 ml of blood at rest.
- Clinical note
- Thickening of this barrier (pulmonary fibrosis) or loss of capillaries (emphysema) lowers the lung's diffusing capacity for carbon monoxide (DLCO).