ELI5, if you get an injury underwater (say in the ocean) that opens the skin and bleeds, what stops your body from intaking water?
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It does happen in fresh water and is called tissue maceration. The water isn’t going to enter the circulatory system due to clotting and vasoconstriction though (and hydrostatic pressure for arterioles), and only seeps into injured tissue and skin. It just happens slowly. In ocean water, there is too much salt for water to enter the body. Instead water travels the other way.
Your blood pressure is higher than the water pressure.
That’s basically the short version.
When a hole between two liquid containers is made, effectively connecting them, the liquid flowing through that hole will be from the higher pressure container to the lower pressure container. In this case your body is the higher pressure container and the ocean is the lower pressure container.
Incidentally this effect is also behind why when the city water supply has been shut off for a while, then turned back on, the water always comes out of your faucet a bit discolored (yellow or brown) until you let it run for a while. And you’re usually told not to drink it until you’ve left it on for a while to flush water through the system.
There are always leaks in a city’s main water pipes at the joins where they turn corners or split in two. It can’t be helped. But most of the time you don’t need to worry at all about the leaks because the pressure guarantees the leak goes OUT OF the pipe, not INTO the pipe. But, if the water pressure is turned off for a while, then that stops being true. The goopy mess of dirty water that was created when the water pushed OUT of the underground pipe into the surrounding dirt now flows backward through the leak back into the pipe once the inside of the pipe is no longer under pressure. Thus when the water is turned on again that gunky stuff that leaked into the pipe has to be expelled back out of the pipe again. After that, the pressure will ensure again that the leak goes in the correct direction – out of the pipe not into the pipe.
It does happen in fresh water and is called tissue maceration. The water isn’t going to enter the circulatory system due to clotting and vasoconstriction though (and hydrostatic pressure for arterioles), and only seeps into injured tissue and skin. It just happens slowly. In ocean water, there is too much salt for water to enter the body. Instead water travels the other way.
Your blood pressure is higher than the water pressure.
That’s basically the short version.
When a hole between two liquid containers is made, effectively connecting them, the liquid flowing through that hole will be from the higher pressure container to the lower pressure container. In this case your body is the higher pressure container and the ocean is the lower pressure container.
Incidentally this effect is also behind why when the city water supply has been shut off for a while, then turned back on, the water always comes out of your faucet a bit discolored (yellow or brown) until you let it run for a while. And you’re usually told not to drink it until you’ve left it on for a while to flush water through the system.
There are always leaks in a city’s main water pipes at the joins where they turn corners or split in two. It can’t be helped. But most of the time you don’t need to worry at all about the leaks because the pressure guarantees the leak goes OUT OF the pipe, not INTO the pipe. But, if the water pressure is turned off for a while, then that stops being true. The goopy mess of dirty water that was created when the water pushed OUT of the underground pipe into the surrounding dirt now flows backward through the leak back into the pipe once the inside of the pipe is no longer under pressure. Thus when the water is turned on again that gunky stuff that leaked into the pipe has to be expelled back out of the pipe again. After that, the pressure will ensure again that the leak goes in the correct direction – out of the pipe not into the pipe.
Your blood pressure is higher than the water pressure.
That’s basically the short version.
When a hole between two liquid containers is made, effectively connecting them, the liquid flowing through that hole will be from the higher pressure container to the lower pressure container. In this case your body is the higher pressure container and the ocean is the lower pressure container.
Incidentally this effect is also behind why when the city water supply has been shut off for a while, then turned back on, the water always comes out of your faucet a bit discolored (yellow or brown) until you let it run for a while. And you’re usually told not to drink it until you’ve left it on for a while to flush water through the system.
There are always leaks in a city’s main water pipes at the joins where they turn corners or split in two. It can’t be helped. But most of the time you don’t need to worry at all about the leaks because the pressure guarantees the leak goes OUT OF the pipe, not INTO the pipe. But, if the water pressure is turned off for a while, then that stops being true. The goopy mess of dirty water that was created when the water pushed OUT of the underground pipe into the surrounding dirt now flows backward through the leak back into the pipe once the inside of the pipe is no longer under pressure. Thus when the water is turned on again that gunky stuff that leaked into the pipe has to be expelled back out of the pipe again. After that, the pressure will ensure again that the leak goes in the correct direction – out of the pipe not into the pipe.
It is possible for your blood pressure to essentially be negative for brief periods of time (at least somewhat locally) and have something that is not blood (usually air) enter your blood.
The brief version is that the same process that causes air to enter your lungs doesn’t really care how it gets there. If you have an opening to your larger blood vessels from either trauma or more commonly a central line (think big IV) in your neck/abdomen, it’s possible to have air enter your blood and give you a bad time.
Look up “air embolism”.
In ELI5 language, if you are actively bleeding, fluid is leaving your body, not coming in to it.
It is possible for your blood pressure to essentially be negative for brief periods of time (at least somewhat locally) and have something that is not blood (usually air) enter your blood.
The brief version is that the same process that causes air to enter your lungs doesn’t really care how it gets there. If you have an opening to your larger blood vessels from either trauma or more commonly a central line (think big IV) in your neck/abdomen, it’s possible to have air enter your blood and give you a bad time.
Look up “air embolism”.
In ELI5 language, if you are actively bleeding, fluid is leaving your body, not coming in to it.
It is possible for your blood pressure to essentially be negative for brief periods of time (at least somewhat locally) and have something that is not blood (usually air) enter your blood.
The brief version is that the same process that causes air to enter your lungs doesn’t really care how it gets there. If you have an opening to your larger blood vessels from either trauma or more commonly a central line (think big IV) in your neck/abdomen, it’s possible to have air enter your blood and give you a bad time.
Look up “air embolism”.
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