Why does rehydrating drinks contain sodium chloride?

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grimstoner

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Just saw that stuff like Rehydrat (and other "rehydrating" drinks like Powerade and Energade) contain sodium chloride (salt), which is a known "dehydrator". Is it because they only add very small amounts? Or is it some combination with other added compounds that negate its effect?
 
Its what the guys above said.

I forget what i learned in biology, but having the right mix of electrolytes means your body will be able to better extract the water - or something like that
 
Taste sweat sometime, it's very salty. It also needs to be replenished.
 
grimstoner said:
Just saw that stuff like Rehydrat (and other "rehydrating" drinks like Powerade and Energade) contain sodium chloride (salt), which is a known "dehydrator". Is it because they only add very small amounts? Or is it some combination with other added compounds that negate its effect?
Click to expand...
You're looking at this from the wrong angle. The important part is the ratio between water:salt, not the components seen in isolation. Salt on its own is a dehydrator, but a drink with a higher water:salt ratio than what is present in the body then it effectively hydrates.
 
Ecco said:
Its what the guys above said.

I forget what i learned in biology, but having the right mix of electrolytes means your body will be able to better extract the water - or something like that
Click to expand...
Your kidneys have these things called nephrons that work to reabsorb water and prevent it leaving your body in your urine. In order to accomplish this the walls of the nephron have proteins that actively pump ions (like Cl[SUP]-[/SUP], Na[SUP]+[/SUP], PO[SUB]4[/SUB][SUP]-[/SUP] and HCO[SUB]3[/SUB][SUP]-[/SUP]) from the nephron into the surrounding kidney tissue.

These ions are solutes. Water is the solvent and water has a tendency to move from an area of low solute concentration to an area of high solute concentration (when this movement happens across a permeable membrane we call it osmosis). So when the solutes are actively (using energy move them) pumped through the membrane against their concentration gradient you end up with more solutes in the surrounding kidney tissue than in the nephron itself. So to balance everything out water moves out of the nephron into the surrounding tissue and eventually finds it's way back into the blood. Everything still left in the nephron moves on to become urine.

Voila! Water reabsorption actually requires NaCl.
 
porchrat said:
Your kidneys have these things called nephrons that work to reabsorb water and prevent it leaving your body in your urine. In order to accomplish this the walls of the nephron have proteins that actively pump ions (like Cl[SUP]-[/SUP], Na[SUP]+[/SUP], PO[SUB]4[/SUB][SUP]-[/SUP] and HCO[SUB]3[/SUB][SUP]-[/SUP]) from the nephron into the surrounding kidney tissue.

These ions are solutes. Water is the solvent and water has a tendency to move from an area of low solute concentration to an area of high solute concentration (when this movement happens across a permeable membrane we call it osmosis). So when the solutes are actively (using energy move them) pumped through the membrane against their concentration gradient you end up with more solutes in the surrounding kidney tissue than in the nephron itself. So to balance everything out water moves out of the nephron into the surrounding tissue and eventually finds it's way back into the blood. Everything still left in the nephron moves on to become urine.

Voila! Water reabsorption actually requires NaCl.
Click to expand...

Thanks for that.
 
A bit OT but where I learnt that salt was important was from a old war movie -> "Farewell to the King" http://mybroadband.co.za/vb/showthr...Watch-Movies?p=6981906&viewfull=1#post6981906

In the film, during world war II Japan invades a island and the tribes are aggravated to kill them for the Allies. The allies would land on the shore and push the japenese into the jungle where the tribes would kill them from a home ground advantage. One of the requests of the tribal leaders was that a path be left to the sea, so that the tribe had a means of obtaining salt or else they'd suffer. As the king put it, "Whats life without a little salt,heh?"

That got me investigating why salt was important :p
 
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