serous membrane, thin and transparent, which surrounds the lungs independently of one another, enclosing them as in a sack. Each pleura folds back on itself, at the pulmonary hilum, it consists of two layers: the inner, or visceral, is necked inwardly to the surface of the lung, the outer, or parietal, paper instead of the inside walls of the box chest and, according to its relationship with other anatomic formations, is divided into three portions: costosternale, diaphragmatic, mediastinal . Between the two pleural includes a virtual cavity (pleural cavity) containing a small amount of serous fluid (pleural fluid). The pleura is a distinguished layer of endothelium called mesothelium (which is the surface turned to the pleural cavity), and a layer of connective tissue rich fibrous elastic fibers. The function of the pleura, as well as facilitating the flow of the lung on the chest wall, is to cooperate in the realization of breathing: during the expansion of the chest cavity, caused by the action of inspiratory muscles, the parietal pleura, following the movements of the walls themselves, causing a negative pressure nel cavo pleurico, rapidamente compensata dall’espansione del polmone, il quale può in tal modo assumere l’aria dall’esterno.
fonte: ok.corriere.it
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