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Atelectasis is the partial collapse or closure of a lung resulting in reduced or absence in gas exchange. It is usually unilateral, affecting part or all of one lung. [2] It is a condition where the alveoli are deflated down to little or no volume, as distinct from pulmonary consolidation, in which they are filled with liquid.
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]
Therefore, the ventilation-perfusion ratio represents the volume of gas that enters the alveoli compared to the volume of blood that enters the alveoli per minute. The ideal V/Q ratio is 1, the most efficient state of pulmonary function when the amount of oxygen entering the lungs equals the amount of oxygen delivered to the body.
Alveoli and their capillary networks 3D medical illustration showing different terminating ends of bronchioles. Alveoli consist of two types of alveolar cell and an alveolar macrophage. The two types of cell are known as type I and type II cells [32] (also known as pneumocytes). [3] Types I and II make up the walls and alveolar septa.
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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.
BERLIN (Reuters) -Chancellor Olaf Scholz will call on Germany's parliament on Monday to declare it has no confidence in him, taking the first formal step towards securing an early national ...