Ever since I started running, all I know is that I need to drink a sh*t ton of electrolytes. But I would like to understand why on a physiological level.
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Aside from blood volume, sodium ion pumps are used in muscle contraction. Too low sodium can cause muscle spasms like a car engine running out of gas.
Aside from blood volume, sodium ion pumps are used in muscle contraction. Too low sodium can cause muscle spasms like a car engine running out of gas.
So to add to this question. Do we need salt in our blood due to the fact that going way back in our evolutionary tree all the way to single cell organisms we spent most of our history evolving in salt water?
Or is salt a vital part of the chemistry of our body, so even if we evolved in fresh water we would have still needed salty blood?
So to add to this question. Do we need salt in our blood due to the fact that going way back in our evolutionary tree all the way to single cell organisms we spent most of our history evolving in salt water?
Or is salt a vital part of the chemistry of our body, so even if we evolved in fresh water we would have still needed salty blood?
There is no ELI5 version, but I can give you an “ELI15 and understand osmosis” version. As you remember from biology class, water will diffuse towards an electrolyte across a semipermeable membrane. This is called “osmosis.”
[There are three basic compartments separated by semipermeable membranes in the body:](https://images.app.goo.gl/FxrkatQ18YyArFK27)
1. The intracellular space, which is the fluid *inside* of cells
2. The interstitial fluid, which is the fluid *around* cells
3. The intravascular space aka plasma fluid volume, which is the fluid *inside your blood vessels*
Dehydration is when you deplete the volume in the intravascular space (“plasma volume” or the volume in your blood vessels). When this tank is low, your blood pressure drops, and you feel dehydrated. Your organs aren’t seeing the perfusion they’re used to. We need to preferentially fill this tank to “rehydrate” you.
When you drink pure water, it distributes to each of your spaces equally, so only **one twelfth** of that glass of water will redistribute into your blood vessels. You need to drink twelve glasses of water to get one glass of water into your arteries and veins!
Now here’s what’s special about sodium.
Sodium is actively pumped out of every cell of your body (and water follows); it is preferentially relocated out of the intracellular space. When you increase your total supply of sodium, you **increase the volume of the extracellular space,** including the volume in your blood vessels.
So when you intake sodium with water, that water is preferentially relocated into your blood vessels rather than everywhere all at once, rehydrating you faster.
Adding sodium will thus **triple** water’s ability to rehydrate you.
**EDIT:**
The gatorade commercials lied to you. Under normal circumstances, sweat does **not** deplete your total store of sodium in a physiologically meaningful way.
**EDIT 2:**
While the kidneys (via the hypothalamic-pituitary-adrenal axis and the renin-angiotensin-aldosterone system) **are** do play a role in “blood saltiness,” they **are not** the primary reason why eating salt/electrolytes restores intravascular volume and are not necessary to answer OP’s question.
Source: I’m a doctor. I give salty IV fluid boluses every single day.
There is no ELI5 version, but I can give you an “ELI15 and understand osmosis” version. As you remember from biology class, water will diffuse towards an electrolyte across a semipermeable membrane. This is called “osmosis.”
[There are three basic compartments separated by semipermeable membranes in the body:](https://images.app.goo.gl/FxrkatQ18YyArFK27)
1. The intracellular space, which is the fluid *inside* of cells
2. The interstitial fluid, which is the fluid *around* cells
3. The intravascular space aka plasma fluid volume, which is the fluid *inside your blood vessels*
Dehydration is when you deplete the volume in the intravascular space (“plasma volume” or the volume in your blood vessels). When this tank is low, your blood pressure drops, and you feel dehydrated. Your organs aren’t seeing the perfusion they’re used to. We need to preferentially fill this tank to “rehydrate” you.
When you drink pure water, it distributes to each of your spaces equally, so only **one twelfth** of that glass of water will redistribute into your blood vessels. You need to drink twelve glasses of water to get one glass of water into your arteries and veins!
Now here’s what’s special about sodium.
Sodium is actively pumped out of every cell of your body (and water follows); it is preferentially relocated out of the intracellular space. When you increase your total supply of sodium, you **increase the volume of the extracellular space,** including the volume in your blood vessels.
So when you intake sodium with water, that water is preferentially relocated into your blood vessels rather than everywhere all at once, rehydrating you faster.
Adding sodium will thus **triple** water’s ability to rehydrate you.
**EDIT:**
The gatorade commercials lied to you. Under normal circumstances, sweat does **not** deplete your total store of sodium in a physiologically meaningful way.
**EDIT 2:**
While the kidneys (via the hypothalamic-pituitary-adrenal axis and the renin-angiotensin-aldosterone system) **are** do play a role in “blood saltiness,” they **are not** the primary reason why eating salt/electrolytes restores intravascular volume and are not necessary to answer OP’s question.
Source: I’m a doctor. I give salty IV fluid boluses every single day.
I was told by a surgeon that the best dehydrator is adding about 1 – 1 1/2 tsp of table salt LITE to your water b/c of the Mg n K in it….much cheaper then buying a product/Gatorade.
I was told by a surgeon that the best dehydrator is adding about 1 – 1 1/2 tsp of table salt LITE to your water b/c of the Mg n K in it….much cheaper then buying a product/Gatorade.
There are a lot of great answers here, but a lot of them aren’t really ELI5.
Most of the things your body does require different types of salt for them to work. Your kidneys can tell how much salt is in your blood, and will make the blood more or less salty by changing the amount you pee.
Your sweat contains both water and salt. If you sweat a lot, you’re going to get thirsty because you don’t have enough water in your system. When you take in water without any salt in it, it makes it so that you have too much water and not enough salt in your blood. This makes your kidneys freak out a bit, and you pee out the extra water. This peeing stops you from re-hydrating.
Normally, our diet has enough salt in it to stop this from happening. However, when you excersize a lot and sweat a lot, you need to replace a lot of water. If you replace a lot of water without eating any salts, you don’t re-hydrate.
There are a lot of great answers here, but a lot of them aren’t really ELI5.
Most of the things your body does require different types of salt for them to work. Your kidneys can tell how much salt is in your blood, and will make the blood more or less salty by changing the amount you pee.
Your sweat contains both water and salt. If you sweat a lot, you’re going to get thirsty because you don’t have enough water in your system. When you take in water without any salt in it, it makes it so that you have too much water and not enough salt in your blood. This makes your kidneys freak out a bit, and you pee out the extra water. This peeing stops you from re-hydrating.
Normally, our diet has enough salt in it to stop this from happening. However, when you excersize a lot and sweat a lot, you need to replace a lot of water. If you replace a lot of water without eating any salts, you don’t re-hydrate.
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