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The average total lung capacity of an adult human male is about 6 litres of air. [1] Tidal breathing is normal, resting breathing; the tidal volume is the volume of air that is inhaled or exhaled in only a single such breath. The average human respiratory rate is 30–60 breaths per minute at birth, [2] decreasing to 12–20 breaths per minute ...
Type I cells are the larger of the two cell types; they are thin, flat epithelial lining cells (membranous pneumocytes), that form the structure of the alveoli. [3] They are squamous (giving more surface area to each cell) and have long cytoplasmic extensions that cover more than 95% of the alveolar surface.
Pulmonary function: increased residual volume, increased total lung capacity, fixed obstruction, low diffusing capacity of the lung for carbon monoxide that corrects with alveolar volume; High-resolution CT scan: diffuse pulmonary nodules 4–10 mm, greater than 20 nodules, mosaic attenuation or air trapping in greater than 50% of the lung
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]
The end-exhalatory lung volume is now well below the resting mid-position and contains far less air than the resting "functional residual capacity". However, in a normal mammal, the lungs cannot be emptied completely. In an adult human, there is always still at least 1 liter of residual air left in the lungs after maximum exhalation. [6]
A lung cavity or pulmonary cavity is an abnormal, thick-walled, air-filled space within the lung. [1] Cavities in the lung can be caused by infections, cancer, autoimmune conditions, trauma, congenital defects, [2] or pulmonary embolism. [3] The most common cause of a single lung cavity is lung cancer. [4]
Another important cell type is the pulmonary neuroendocrine cell. These are innervated cells that only make up around 0.5% of the respiratory epithelial cells. [7] The ciliated cells are columnar epithelial cells with specialized ciliary modifications. The ciliated cells make up between 50 and 80 per cent of the epithelium. [8]
The lungs are the largest organs in the lower respiratory tract. The lungs are suspended within the pleural cavity of the thorax. The pleurae are two thin membranes, one cell layer thick, which surround the lungs. The inner (visceral pleura) covers the lungs and the outer (parietal pleura) lines the inner surface of the chest wall. This ...