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Pleura (or Pleurae) and Pleural Cavity of the Lungs

An expanded view of the thorax

  • Each lung is enveloped in its own double-membrane image descriptionpleural sac.
An expanded view of the thorax magnifying the pleura
Pleural sac labeled in a magnified the pleura
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  • The inner membrane of the sac adheres to the outer surface of the lung and is called the image descriptionvisceral pleura.
An expanded view of the thorax magnifying the pleura
The visceral pleura labeled in a magnified the pleura
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  • The outer membrane is called the image descriptionparietal pleura and is an extension of the visceral pleura, which doubles back on itself at the hilum (hilus) and runs along the surfaces of the rib cage, diaphragm, and mediastinum.
An expanded view of the thorax magnifying the pleura
The parietal pleura labeled in a magnified the pleura
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  • Both pleurae are serous membranes,¬†which secrete a thin layer of watery pleural fluid into the image descriptionpleural cavity that separates them.
An expanded view of the thorax magnifying the pleura
The pleural cavity labeled
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  • An open space does not normally exist in the pleural cavity because the pleural fluid loosely attaches the two membranes. During breathing movements, this slippery seal allows the two membranes to slide past one another. The pleurae also form a barrier that helps protect the lungs from infections that can occur elsewhere in the thoracic cavity.

An Overview of the Pleura and Pleural Cavity of the Lungs:

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Test yourself by observing the Pleura and Pleural Cavity of the Lungs
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