Lung Parenchyma

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Lung parenchyma is the part of the lung that's involved in gas transfer. It's made up of a large number of thin-walled alveoli that form a large surface area. The alveoli are held open by transpulmonary pressure, or prestress, which is balanced by tissues forces and alveolar surface film forces.

Lung parenchyma includes the functional gas-exchanging alveoli, which are lined by epithelium and covered by a thin liquid-phase blood.

Lung parenchymal abnormalities can be due to:

• A disease of the pulmonary interstitial tissue
• The bronchial tree
• The cardiovascular system
• Abnormal alveolar filling with fluid, blood, cells, or tumor

A pulmonary infiltrate is a substance denser than air, such as pus, blood, or protein, which lingers within the parenchyma of the lungs. Pulmonary infiltrates are associated with pneumonia, tuberculosis, and sarcoidosis.