A reaaaaaaaally stupid question.

[Dutchpower]

If we humans need salt so much, then why is it so bad to drink salt water when in a survival situation?

[vizi]

They put iodine in the salt......

[LoZz]

If we humans need salt so much, then why is it so bad to drink salt water when in a survival situation?

it dehydrates you, making you need more water

[Justinian]

If we humans need salt so much, then why is it so bad to drink salt water when in a survival situation?

We need salt so much because there's iodine in salt intended for human consumption, and though we require trace amounts of sodium daily, it is way less than what you would have in a cup of salt water. When you drink a highly salty substance, you become dehydrated, meaning you would drink more of the salt water, get more dehydrated, and eventually die. Plus, it tastes like crap.

[milns]

If we humans need salt so much, then why is it so bad to drink salt water when in a survival situation?

Actually it is good to drink salt water (in very limited quantities of course) in hot weather, because you swet and lose salt which is needed for our bodies. So in order you din't get overdose, scientists has come up with salt pills.

[Dutchpower]

I find it stupid that we need that much water in short amount of time anyway, i mean arent we humans made for hot weather(africa?) that means that we are stuck to water holes or else we will die(from a survival aspect)

How much water does a monkey need a day?

[Erich von Manstein]

Given the biological/chemical nature of this thread, I have moved it to the Athenaeum. Let's stay on-topic, please.

[imb39]

Sea water is not good for us because there is far too much salt in it. It overloads our kidneys and damages them. You can drink it a little but not for too long. I suspect there is so much salt in it that it might be a diuretic (you'll lose more water getting rid of the salt than you got from drinking the sea water.

Salt is needed to ensure that osmosis works properly in our bodies and, I think, it is also an electrolyte and used by the nervous system.

The iodine aspect is a red herring as that has only been a relatively recent discovery/addative (I suspect - I haven't checked).

[The Fish]

Oh dear.

Okay, first up, sodium is an essential mineral for a number of physiological responses. It is kept in tight control (the serum sodium level must be kept between 136-145 mmol/L) for a number of reasons. First of all, all cells in the body need to maintain a precise balance of ion charges between the outside and the inside of the cell. Na+ (the sodium ion) is one of the main ions used in this process. All nerve transmissions also require Na+ to work; when a nerve is excited, sodium and potassium ions are exchanged across the cell membrane in a process known as depolarization. This is how we think, move, control our bodies, everything.

Why is drinking sea water bad? Because salt water adds a number of osmotic particles to our blood. Basically, if you have a membrane with different concentrations of osmotic particles on either side, the two sides will try to balance each other out, so that the concentrations equal. This is done when water crosses the membrane to dilute the side with more particles. Let me give you an example:

Right now, my cells and my blood are in osmotic balance. That is, all the "stuff" inside my cells (proteins and ions, mainly) are about equal to the amount of "stuff" (also mainly proteins and ions) in my blood. This means that there isn't a net movement of water into or out of my cells. Now let's say I drink a liter of sea water. The osmotic particles in the water (sodium and other ions, mainly) get added to my blood. Suddenly, there is more "stuff" in my blood than in my cells. But my cells don't "want" to be different from the blood, and since the ions and proteins can't cross the cell membranes, water does instead. Water rushes out of the cells to "dilute" all the ions in the blood. Result: cells get dehydrated, blood volume increases.

If I had drunk a large amount of pure water, though, then the opposite would have happened. My blood would have had LESS "stuff" in it, water would have moved into the cells, and the cells would have swollen. This happens sometimes in athletes who drink too much water: their brain cells can actually swell to the point where death ensues. Of course, we have a bunch of control systems to keep osmotic concentrations in balance, but they're very complex, and I'm not sure how much you guys want to know...

Edit: Oh yes, and iodine is VERY important. It is used to make thyroid hormone, which is an essential regulatory hormone for metabolism and other important physiological actions. Low iodine can lead to goiters (an enlargement of the thyroid gland as it struggles to make more thyroid hormone). Hypothyroidism (low thyroid hormone levels) is a very serious condition that can lead to cardiac problems, coma (myxedema coma, specifically), and death. In children, low iodine levels leads to a condition known as cretinism, which leads to severe problems with physical and intellectual development. This disease was the main impetus behind adding iodine to salt.

[chris_uk_83]

@ Fish

+ rep for that lovely explanation!

[felicissimus]

In medio stat virtus (In the middle is the virtue )

You see,everything is considered good or bad according to its proper dose,to staying close to the midst .If it's not measured well is bad or even poisoneous .And for everything is like that,even a laughter is nice when measured,ugly-when overpowered.