Re: what force holds the visceral and parietal pleural membranes together

Hi Cori
That was an interesting question, briefly there is no physical attachment, 
they are held in place by pleural membranes, constant negative pressure 
also plays a part. Read the information below for a more in depth reply and
be sure to go to the websites listed in order to get more information 
regarding your question.

The lungs do not contain any skeletal muscle and the smooth muscle present 
in the lung is associated with the bronchial system.  Thus, the lung is 
incapable of expanding and contracting by itself due to a lack of proper 
muscularization.  Lung expansion is dependent on the skeletal muscle 
associated with the chest wall and the diaphragm.  The lungs are only 
physically attached at their hilus, there is no physical attachment to the 
chest wall or diaphragm.  Instead, the lungs are held to the chest wall 
and diaphragm by the pleural membranes.  The surface of the lungs is 
covered by a thin epithelial membrane termed the visceral pleural 
membrane.  At the hilus, the visceral membrane is reflected back and 
covers the chest wall and diaphragm.  The pleural membrane covering the 
chest wall and diaphragm is termed the parietal pleural membrane.

www.kent.edu/biology/courses/60495/Resp.htm


The Lungs are paired organs in the thoracic cavity, they are enclosed and 
protected by the pleural membrane (one of the three serous membranes of 
the body). The parietal pleura is the outer layer, attached to the wall of 
the thoracic cavity (lining it). The visceral pleura is the inner layer, 
covering the lungs themselves (these membranes are continuous at the hilus 
of the lung where the bronchial tree and pulmonary vessels enter). There 
is a small potential space, the pleural cavity, between the pleurae, which 
contains lubricating serous fluid secreted by the membranes. The potential 
space becomes an actual space when it fills with air (pneumothorax), blood 
(hemothorax), pus, or fluid due to wounds, surgery, infection, or 
inflammation (pleurisy).  The pleural cavity is a "potential" space, 
because normally, when lungs are fully inflated, they conform to the 
entire chest cavity.  The only thing actually IN the pleural cavity is a 
thin layer of serous fluid (which creates a surface tension which holds 
the lungs to the chest wall).  A constant negative pressure inside this 
space keeps the lungs inflated and makes them "stick" to the chest wall. 

www.msj.edu/murray/Ch23Martini.htm


Thanks for taking the time to send in a question to Mad Sci

June Wingert
Associate Scientist
Genetics Firm 
Houston, Texas