Pulmonary capillary

Pulmonary capillaries are the thin-walled microvascular networks surrounding lung alveoli, forming a vast sheet-like bed essential for gas exchange where deoxygenated blood receives oxygen and releases carbon dioxide. Composed primarily of continuous endothelial cells with tight junctions and a basement membrane, they enable selective permeability for gases, water, and small molecules while minimizing protein leakage under normal conditions. These capillaries receive all cardiac output via pulmonary arteries and balance hydrostatic, osmotic, and alveolar forces to prevent fluid accumulation in the interstitium or airspaces. Nonventilatory roles include metabolic processing due to their large surface area and exposure to the entire blood volume. In disease, endothelial injury from inflammation, toxins, or hypoxia increases permeability, causing interstitial or alveolar edema that impairs gas exchange, as seen in ARDS or heart failure. While not a molecular therapeutic target like receptors or enzymes, their endothelial cells are studied for dysfunction in conditions like pulmonary hypertension or BPD, where drugs aim to protect barrier integrity indirectly.

Other names

pulmonary capillariesalveolar capillarieslung capillaries