Do organs compress whilst diving?

[DrGonzo]

Do the heart, liver, etc get compressed at 30m or is the effect not much?

 

[ScubaInChicago]

The body is mostly water with connective tissue, so basically no. Although, at 100'/30m depth your respiratory performance is halved.

Carbon Dioxide, Narcosis, and Diving | Global Underwater Explorers

 

[Kevrumbo]

With regard to the Lungs -yes and no:

In free diving (breath hold), as a diver descends, his lungs decrease in size according to Boyle's Law. But this isn't the case when using scuba because a diver fills his lungs completely with every breath supplied by the regulator at ambient pressure.

 

[seeker242]

For the heart it's the opposite. Pressure on the extremities causes increased blood flow in the chest which expands the heart.

 

[EricTheDood]

If the water at 30m is noticeably colder due to thermoclines, then yes, certain organ(s) do get compressed .

 

[toby43]

For these purposes it is enough to know that liquids dont compress with pressure

 

[Dan]

So, each lung (left & right sides) of a free diver would be about 25% of his / her original size (about the size of a fist) at 100' deep?

 

[DrGonzo]

For the heart it's the opposite. Pressure on the extremities causes increased blood flow in the chest which expands the heart.

If liquids at the extremities don't compress, why is there increased blood flow?
Also, when running on a treadmill there is increased blood flow - does that expand the heart also?

 

[mattia_v]

In theory

If liquids at the extremities don't compress, why is there increased blood flow?
Also, when running on a treadmill there is increased blood flow - does that expand the heart also?

I don't think compression is the only factor, but also loss of a gravity, which is usually what keeps a proportion of your venous blood in your limbs rather than your core. Immersion does shift blood volume towards the central circulation, so part of the roughly 2/3 of your blood that is usually in your venous pool may shift and become more actively involved in the circulatory system.

Diving leads to increased venous return, so more volume in the right side of the heart, and thus the left side of the heart, and thus to greater cardiac output.

The same happens in exercise on a treadmill, though due to different reasons (greater demand, larger breaths which 'suck' blood into the chest, muscles in legs 'pushing' blood into the central venous system), so yes, greater flow, and more output.

Your heart normally pumps about 4 to 6 liters every minute (cardiac output, basically heart rate x stroke volume, the amount pumped out with each heartbeat). This can increase to 20 or 30 liters per minute - a large part of this is heart rate, but some of it is an increase in stroke volume.

 

[fmerkel]

Immersion Diuresis (Urge to Urinate)
Organs do not compress, nor do the lungs on a scuba dive. Anyone thinking otherwise needs to go back for some remedial dive physiology lessons.