March 25, 2011
Water is a critical element of the body, and adequate hydration is a must to allow the body to function. Up to 75% of the body's weight is made up of water. Most of the water is found within the cells of the body. The rest is found in the extracellular space, which consists of the blood vessels and the spaces between cells. Dehydration occurs when the amount of water leaving the body is greater than the amount being taken in. The body is very dynamic and always changing. This is especially true with water in the body. We lose water routinely when we breathe and humidified air leaves the body, this can be seen on a cold day when the breath you see in the air is water that has been exhaled, sweat to cool the body, and eliminate waste by urinating or having a bowel movement. In a normal day, a person has to drink a significant amount of water to replace this routine loss. The formula for daily fluid requirements depends upon an individual's weight. The body is able to monitor the amount of fluid it needs to function. The thirst mechanism signals the body to drink water when the body is dry. As well, hormones like anti-diuretic hormone (ADH) work with the kidney to limit the amount of water lost in the urine when the body needs to conserve water.
Dehydration occurs because there is too much water lost, not enough water taken in, or most often a combination of the two. Diarrhea is the most common reason for a person to lose excess amounts of water. A significant amount of water can be lost with each bowel movement. Worldwide, more than four million children die each year because of dehydration from diarrhea. Vomiting can also be a cause of fluid loss. It is lost in the vomitus, but it is difficult for a person to replace water by drinking it if they have nausea and are unable to tolerate liquids. The body can lose significant...