IntroductionMaintain Electrolyte BalanceCredit:
If you think about it hard enough, electrolytes include salts, acids and bases. In relation to the term electrolyte balance, more often than not it refers to the salt balance within the body. You may ask, of all the components found in the body, why salt? Well first of all remember the phrase “where sodium goes, water follows.” That’s the reason why salts are crucial in controlling the movement of fluid and serves as a source of minerals that is essential for secretory activity, excitability and the permeability of membranes.
Dynamic Activity of SaltsSalt Affects Elecrolyte BalanceCredit:
Just to be clear, the term salt when referring to anatomy is not only referring to the common “table salt.” Sodium, potassium and calcium are just some examples of salts that we are referring to. We can get salts from various sources like the foods we eat and the fluids we drink. Some salts are even generated by the cells during metabolic activity. The irony is, obtaining the needed electrolytes is never really a problem.  Ample amounts of salts can be obtained from natural foods and most of us who eat processed foods already contain exorbitant quantities. 
Water and Electrolyte BalancingCredit: are lost by means of urine, feces and perspiration. Although the salt excreted by the body is tolerable, some circumstances pave way for us to lose more salt than the normal. An example is during a hot day, increased perspiration means that a lot of salt is also lost. Some disorders of the gastrointestinal tract can also bring about large salt losses. 
The Role of Sodium in Fluid and Electrolyte Balance
 Extra Cellular Fluid Electrolyte BalanceCredit:
One of the most important functions of the kidneys is to regulate the balance between the intake of sodium and the output of it. Sodium holds a key role when it comes to fluid and electrolyte and the overall body homeostasis. Sodium bicarbonate and sodium chloride constitutes to about 95% of all the solutes found in the extracellular fluid compartment. Of the 300 mOsm concentration of the ECF, the two salts combine for about 280 mOsm. 
Considering the importance of sodium, it is the most abundant cation found in the ECF and is the only one that exerts significant osmotic pressure. With the dynamic actions of intake and output of salts, it is important to note that the levels of sodium may change in the body, its concentration on the ECF remains stable because the water volume in it immediately makes adjustments. This is where the phrase “where sodium goes, water follows.”  
SummaryOsmotic equilibrium maintenanceCredit:
It is important to remember that all fluids of the body are in osmotic equilibrium. With the vast influence of sodium, a change in the levels of plasma sodium have bearing not only on plasma volume and blood pressure but also has effects on the intercellular fluid compartment and the IF volumes.
In addition to this, it is also important to note that sodium can freely move back and forth between the extracellular fluid and the body secretions. Lastly, the acid-base control mechanism of the kidney is coupled with sodium transport.