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A pulmonary alveolus (pl.: alveoli, from Latin alveolus, "little cavity"), also known as 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 ...
A mammary alveolus (pl.: alveoli, from Latin alveolus, "little cavity") is a small cavity or sac found in the mammary gland. [1] [2] Mammary alveoli are the site of milk production and storage in the mammary gland. [1] [2] Mammary alveoli cluster into groups called mammary lobules, and each breast may contain 15 to 20 of these lobules.
Type I cells provide 95% of the surface area of each alveoli and are flat ("squamous"), and Type II cells generally cluster in the corners of the alveoli and have a cuboidal shape. [35] Despite this, cells occur in a roughly equal ratio of 1:1 or 6:4. [34] [35] Type I are squamous epithelial cells that make up the alveolar wall structure.
Alveolar lung diseases are classified as processes that affect these units that ultimately lead to issues with ventilation. There are a number of different causes of insult to the alveoli including build up of fluid, hemorrhage, infection, malignancy and build up of protein and mineral deposits. Conditions classified under alveolar lung disease ...
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]
The conducting zone also functions to offer a low resistance pathway for airflow. It provides a major defense role in its filtering abilities. The respiratory zone includes the respiratory bronchioles, alveolar ducts, and alveoli, and is the site of oxygen and carbon dioxide exchange with the blood. The respiratory bronchioles and the alveolar ...
An acinus (/ ˈæsɪnəs /; pl.: acini; adjective, acinar / ˈæsɪnər / or acinous) refers to any cluster of cells that resembles a many-lobed " berry," such as a raspberry (acinus is Latin for "berry"). The berry-shaped termination of an exocrine gland, where the secretion is produced, is acinar in form, as is the alveolar sac containing ...
The zones of the lung divide the lung into four vertical regions, based upon the relationship between the pressure in the alveoli (PA), in the arteries (Pa), in the veins (Pv) and the pulmonary interstitial pressure (Pi): Zone 1: PA > Pa > Pv. Zone 2: Pa > PA > Pv. Zone 3: Pa > Pv > PA.