Major Electrolyte Levels in the Blood: Sodium

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  • 0:31 Sodium
  • 3:57 Hypernatremia
  • 6:05 Hyponatremia
  • 8:01 Lesson Summary
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Lesson Transcript
Instructor: Artem Cheprasov

Artem has a doctor of veterinary medicine degree.

This lesson discusses the electrolyte sodium. We will go over what it is, why it's important, and what may cause the relative levels of sodium to increase or decrease in the body.

An Important Component of Salt

Nowadays, salt is everywhere. It's on our roads during the winter time and in the food we eat. But too much salt on our roads eats away at our cars, and too much salt in our body can really hurt us.

But part of the compound that makes up salt is actually useful to our body in normal amounts, and can tell us quite a bit about what's going on inside a person if imbalances of it are found on blood work.

This part of salt is called sodium and we'll be discussing its importance in life and in medicine.

What Is Sodium?

Let's take a look at the good old periodic table. You probably groaned as I said that. But I want you to be able to understand the fundamental parts first, so you can better appreciate the more complex ones later.

In the left-most column of the periodic table is a symbol that's spelled Na. This is the symbol for sodium. It is one half of NaCl. NaCl is also known as sodium chloride, or, more colloquially, as table salt, that's found in too high a quantity in many of the foods we eat.

In our biological systems, sodium is an electrolyte. An electrolyte is a compound that becomes an ion when dissolved in a solvent. A solvent is something that dissolves something else.

For example, if you go to the kitchen right now and dump some table salt, our compound, into a glass of water, you'll notice that the salt dissolves within it. The water is dissolving the salt. Therefore, the water is the solvent.

The salt dissolves in the water and forms into ions. An ion is an atom with too many or too few electrons (the negatively charged particles that make up an atom). When dissolved, sodium forms a cation that is represented as Na+. A cation is an ion with a positive electrical charge. The other half of our dissolved salt is made up of chloride, represented by Cl-. Chloride is an anion, an ion with a negative electrical charge, hence the minus sign after it.

The way I remember that a 'c'ation has a positive charge is because a cation has a 'c'ross (plus sign) next to it, with both 'cation' and 'cross' starting with the letter 'c'. By default, an anion has to have a negative sign next to it.

I'm telling you all of this for a reason. These charges, which the electrolytes in our body carry, are important factors in making sure the cells in our body function properly. For instance, without these electrical charges found on the cations and anions in our body, our nerve cells wouldn't be able to signal to one another. This means we wouldn't be alive, period.

With that in mind, you should know that sodium is the most important extracellular cation. That is to say, it is the most important cation found outside of cells in our body.

Sodium helps to regulate blood pressure, nerve conduction, muscle contraction, and much more! No sodium, and you'd go limp! Too much sodium and you could die, too!

Because of this, your body does whatever it can to ensure that the concentration of sodium within your body remains constant so that these biochemical processes can function properly.

By the way, the concentration of sodium refers to how much sodium is dissolved within a set amount of fluid. Let's go back to our kitchen to explain this. If you pour a cup of water and add one teaspoon of salt, there will be a set amount of sodium dissolved in that specific amount of water. That is your concentration. If you put two teaspoons of salt into the same volume of water instead, then the concentration of sodium would be higher this time around, since the amount of water stayed the same but the amount of salt put into that same volume of water increased two-fold. This will be a very important point to remember for the rest of this lesson.

Causes of Hypernatremia

When the concentration of sodium serum is abnormally high, with a concentration above 145 mEq/L we term this hypernatremia. The serum is the part of your blood that contains electrolytes and its electrolyte measurements are reflective of what's going on with the electrolyte balance in your body as a whole.

Don't worry about the details of what mEq/L means for our lesson - just understand that it's a term that reflects an electrolyte's concentration.

What I'd like for you to realize instead is that the definition implies that it's not all about the amount of sodium in the body, it's about the amount of it relative to the water it is dissolved in. And one of the biggest reasons you may have an increase in concentration of sodium in the body is if you don't get enough water or lose too much of it. In other words, you're dehydrated. It's something we can all relate to.

Dehydration implies you don't have enough water in your body. If the amount of water decreases, and the amount of sodium in your body stays the same, then you become hypernatremic, or in a state of hypernatremia. If the amount of sodium in your body decreases but the amount of water decreases even more, you'd still be considered hypernatremic despite the loss of sodium.

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