Well over half of the body's weight is made up of water. Doctors think about the body's water as being restricted to various spaces, called fluid compartments. The three main compartments are
Fluid within cells
Fluid in the space around cells
Blood
To function normally, the body must keep fluid levels from varying too much in these areas.
Some minerals Overview of Minerals Minerals are necessary for the normal functioning of the body’s cells. The body needs relatively large quantities of Calcium Chloride Magnesium Phosphate read more —especially the macrominerals (minerals the body needs in relatively large amounts)—are important as electrolytes. Electrolytes are minerals that carry an electric charge when they are dissolved in a liquid such as blood. The blood electrolytes—sodium, potassium, chloride, and bicarbonate—help regulate nerve and muscle function and maintain acid-base balance Overview of Acid-Base Balance An important property of blood is its degree of acidity or alkalinity. The acidity or alkalinity of any solution, including blood, is indicated on the pH scale. The pH scale, ranges from 0 ... read more and water balance About Body Water Water accounts for about one half to two thirds of an average person’s weight. Fat tissue has a lower percentage of water than lean tissue and women tend to have more fat, so the percentage... read more .
Electrolytes, particularly sodium Overview of Sodium's Role in the Body Sodium is one of the body's electrolytes, which are minerals that the body needs in relatively large amounts. Electrolytes carry an electric charge when dissolved in body fluids such as blood... read more , help the body maintain normal fluid levels in the fluid compartments because the amount of fluid a compartment contains depends on the amount (concentration) of electrolytes in it. If the electrolyte concentration is high, fluid moves into that compartment (a process called osmosis). Likewise, if the electrolyte concentration is low, fluid moves out of that compartment. To adjust fluid levels, the body can actively move electrolytes in or out of cells. Thus, having electrolytes in the right concentrations (called electrolyte balance) is important in maintaining fluid balance among the compartments.
The kidneys help maintain electrolyte concentrations Water and electrolyte balance The kidneys are bean-shaped organs that figure prominently in the urinary tract. Each is about 4 to 5 inches (12 centimeters) long and weighs about one third of a pound (150 grams). One lies... read more by filtering electrolytes and water from blood, returning some to the blood, and excreting any excess into the urine. Thus, the kidneys help maintain a balance between daily consumption and excretion of electrolytes and water.
If the balance of electrolytes is disturbed, disorders can develop. For example, an electrolyte imbalance can result from the following:
Becoming dehydrated Dehydration Dehydration is a deficiency of water in the body. Vomiting, diarrhea, excessive sweating, burns, kidney failure, and use of diuretics may cause dehydration. People feel thirsty, and as dehydration... read more or overhydrated Overhydration Overhydration is an excess of water in the body. People can develop overhydration if they have a disorder that decreases the body’s ability to excrete water or increases the body's tendency... read more
Taking certain drugs
Having certain heart, kidney, or liver disorders
Being given intravenous fluids or feedings in inappropriate amounts
