Our bodies need adequate amounts of salt and water to maintain good health. And we don’t have any storage facilities for either.

The human body is made up primarily of water. About 60 percent to 70 percent of the body is water. And 70 percent to 80 percent of the brain is water. Therefore, small changes in hydration status can have drastic repercussions.

In fact, the human body is constantly losing water. Breathing exhales water vapor, causing water levels to decline. Water is also lost through urination and defecation; it even evaporates off the skin.

More water is lost in warmer environments, at high altitudes, when the humidity of the environment isvery low (such as in the desert), and during exercise. In addition, anything that increases the heart rate can cause water loss.

As noted, humans can’t store water. Therefore, we need to continually supply the body with more water to maintain proper hydration.

Because water is so important, the body has tight regulatory mechanisms to control fluid status. One of the primary methods is through hormonal production in the pituitary gland — specifically, the posterior pituitary — where antidiuretic hormone (ADH) is secreted.

One job of ADH is to signal the kidneys to reabsorb water when the body is dehydrated. So in a dehydrated state, the pituitary gland will increase the release of ADH to help the body minimize the consequences of dehydration.

Signs of dehydration include dry, flaky skin; sunken eye sockets; a dry tongue; and ridging in the nails. A thorough physical exam can identify many of the signs of dehydration.