How is water pressure communicated to the lungs?

[pauldw]

I think the brain is not compressed, which is probably good.

 

[gmerick]

"In the normal adult, the lungs weigh approximately 1000 g. Lung volume increases from about 250 mL at birth to 6000 mL in the adult."

When lungs compress, the alveoli sacs can collapse completely leaving them liquid filled, and non-compressable. The alveolar liquid (pulmonary surfactant) also partially fills the smaller bronchi. The normal 6 liters of air will be compressed into the rigid structures of the lungs and airway (bronchi, trachea, sinuses). The much smaller volume of the non-compressible structures in relationship to total thoracic volume makes deep breath hold diving possible.

 

[pauldw]

So someone help me with my confusion. I thought the pleural membranes were supposed to be in constant contact with each other, and if they weren’t then there would be pain. I’m picturing the description here has the lungs turning into two little masses of tissues hanging from the bronchi, with space around them because the rib cage certainly hasn’t collapsed. I’m trying to visualize exactly what happens in there.

 

[GJC]

So someone help me with my confusion. I thought the pleural membranes were supposed to be in constant contact with each other, and if they weren’t then there would be pain. I’m picturing the description here has the lungs turning into two little masses of tissues hanging from the bronchi, with space around them because the rib cage certainly hasn’t collapsed. I’m trying to visualize exactly what happens in there.

The pleural membranes normally have a small amount of pleural fluid that lubricates the outside surface of the lungs and inside surface of the rib cage. Air in the pleural space (pneumothorax) is not normal. Pain is caused by lack of pleural fluid (with pleural surfaces rubbing against each other) or from inflamation causing pleurisy.

Lung tissue is composed of a good amount of solid material (bronchi, bronchioles, alveoli and blood vessls) and liquids including blood and a small amount of fluid in alveoli. These don't collapse under pressure, so there is a substantial amount of lung material in the chest plus whatever pushes up on the diaphragm from the abdomen as air in the lungs is compressed under pressure.

 

[pauldw]

The pleural membranes normally have a small amount of pleural fluid that lubricates the outside surface of the lungs and inside surface of the rib cage. Air in the pleural space (pneumothorax) is not normal. Pain is caused by lack of pleural fluid (with pleural surfaces rubbing against each other) or from inflamation causing pleurisy.

Lung tissue is composed of a good amount of solid material (bronchi, bronchioles, alveoli and blood vessls) and liquids including blood and a small amount of fluid in alveoli. These don't collapse under pressure, so there is a substantial amount of lung material in the chest plus whatever pushes up on the diaphragm from the abdomen as air in the lungs is compressed under pressure.

OK, but what’s happening when, as someone pointed out earlier, things are smushed down to 1/10?

 

[Angelo Farina]

OK, but what’s happening when, as someone pointed out earlier, things are smushed down to 1/10?

It happens that lungs are collapsed, partially filled of liquids. Diaphragm is raised and the organs in abdomen are sucked in the upper part of the rib cage.
Some damage can occur due to these mechanical stress conditions, and several deep divers suffered of lung aemorragy or pneumothorax.
Nevertheless, no broken ribs were reported.
These are extreme conditions, which can be deadly for "normal people".

 

[GJC]

OK, but what’s happening when, as someone pointed out earlier, things are smushed down to 1/10?

Only the gases are smushed smaller. The solids and liquids get re-arranged as the gases within them are compressed.