How come whenever we submerge ourselves underwater our entire body doesn’t fill with water?


We have a lot of orifices and how does our body block off the water pressure from consuming us?

In: 1

All your orifices are closed except for your nose and the pressure of air inside of your lungs keeps the water from filling them. No other orifice opens your body cavity to external environment without a closure of some sorts.

Critters who filled up with water because no orifice prevention didn’t live long enough to reproduce. Also critters who had orifice protection did live to produce.

Few things to bear in mind:

1) The human torso is airtight and has no space for water.

2) The introduction of water into the torso is a bad bad thing. Water is full of contaminants and bacteria and viruses. Internal organs are not prepared to deal with that and infection is likely.

3) The main orifices that have access to the outside are the esophagus and the anus and both come with multiple separate seals. Both are related to the digestive system.

But, aside from wounds that open up a new hole in the torso, there’s no way for water to enter the torso.

Unlike an empty jar without a lid we are filled with stuff and are not actually empty in the way we would need to be to “full” with water.

Even an empty container would need to allow the trapped air to escape in order to fill with water.

So looking at each one of the openings we have.

Ears are blind tubes, they fill with water but empty quickly.

The mouth has air in it and we can get water in easily but we have a natural reflex to close the mouth so you might get a mouthful but not much more.

When we close our mouth we deal off the lungs and stomach from filling.

The anus is tight enough to prevent fluid leaking when you have diarrhea so not water gets in there.

Your urethra, the hole you pee out of is an open narrow tube, with a muscle to close it. It doesn’t leak so it is water tight.

The vaginal opening is a blind tube with air inside and might get a little water in it when you are inverted but not owning one, I can say for sure but it is not like an open jar and narrow so if it does, it would be probably unnoticed.

The human body is actually shaped like a complex donut from your mouth to your anus you are open all the way through but that path is filled with food and has valves that control the flow in and out at a number of points.