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Almost any type of lung tumor or lung cancer can compress the alveoli and reduce gas exchange capacity. In some cases the tumor will fill the alveoli. [33] Cavitary pneumonia is a process in which the alveoli are destroyed and produce a cavity. As the alveoli are destroyed, the surface area for gas exchange to occur becomes reduced.
The major function of the lungs is gas exchange between the lungs and the blood. [67] The alveolar and pulmonary capillary gases equilibrate across the thin blood–air barrier . [ 34 ] [ 68 ] [ 69 ] This thin membrane (about 0.5 –2 μm thick) is folded into about 300 million alveoli, providing an extremely large surface area (estimates ...
The bronchi function to carry air that is breathed in through to the functional tissues of the lungs, called alveoli. Exchange of gases between the air in the lungs and the blood in the capillaries occurs across the walls of the alveolar ducts and alveoli.
The alveoli are tiny air sacs in the lungs where gas exchange takes place. The mean number of alveoli in a human lung is 480 million. [11] When the diaphragm contracts, a negative pressure is generated in the thorax and air rushes in to fill the cavity. When that happens, these sacs fill with air, making the lung expand.
The tendency for the alveoli to collapse is therefore almost the same at the end of exhalation as at the end of inhalation. Thirdly, the surface tension of the curved watery layer lining the alveoli tends to draw water from the lung tissues into the alveoli. Surfactant reduces this danger to negligible levels, and keeps the alveoli dry. [6] [37]
Micrograph showing hemosiderin-laden alveolar macrophages, as seen in a pulmonary hemorrhage. H&E stain.. An alveolar macrophage, pulmonary macrophage, (or dust cell) is a type of macrophage, a professional phagocyte, found in the airways and at the level of the alveoli in the lungs, but separated from their walls.
Pulmonary surfactant thus greatly reduces surface tension, increasing compliance allowing the lung to inflate much more easily, thereby reducing the work of breathing. It reduces the pressure difference needed to allow the lung to inflate. The lung's compliance, and ventilation decrease when lung tissue becomes diseased and fibrotic. [3]
Red arrows indicate secreted lamellar bodies, and green arrows indicate lamellar bodies in the cytoplasm. Scale bar = 200 nm. In cell biology, lamellar bodies (otherwise known as lamellar granules, membrane-coating granules (MCGs), keratinosomes or Odland bodies) are secretory organelles found in type II alveolar cells in the lungs, and in keratinocytes in the skin.