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A pulmonary alveolus (pl. alveoli; from Latin alveolus 'little cavity'), also called an air sac or air space, is one of millions of hollow, distensible cup-shaped cavities in the lungs where pulmonary gas exchange takes place. [1] Oxygen is exchanged for carbon dioxide at the blood–air barrier between the alveolar air and the pulmonary ...
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.
After extraction of a tooth, the clot in the alveolus fills in with immature bone, which later is remodeled into mature secondary bone. Disturbance of the blood clot can cause alveolar osteitis, commonly referred to as "dry socket". With the partial or total loss of teeth, the alveolar process undergoes resorption.
This marked difference between the composition of the alveolar air and that of the ambient air can be maintained because the functional residual capacity is contained in dead-end sacs connected to the outside air by fairly narrow and relatively long tubes (the airways: nose, pharynx, larynx, trachea, bronchi and their branches down to the ...
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.
The rest of the difference is due to the continual uptake of oxygen by the pulmonary capillaries, and the continual diffusion of CO 2 out of the capillaries into the alveoli. The alveolar pO 2 is not routinely measured but is calculated from blood gas measurements by the alveolar gas equation .
Intraalveolar blood vessels (pulmonary capillaries) are thin walled vessels adjacent to alveoli which are subject to the pressure changes described by zones 1-3. Flow in zone 4 is governed by the arteriointerstitial pressure difference (Pa − Pi). This is because as Pi rises, the arterial caliber is reduced, thereby increasing resistance to flow.
The alveolar type II epithelial cells are more resistant to damage, so after an insult to the alveoli, most of the damage will occur to the alveolar type I epithelial cells. [5] Left side demonstrate the structure of a normal alveolus including the difference between type I and type II alveolar epithelial cells.