Water is crucial to the maintenance of life. The molecular structure of water is critical to its vital functions.

Due to the polar nature of water molecules, these molecules “stick” to each other through the formation of hydrogen bonds. This is why water falls from the sky in “drops” or pools on the ground in “sheets” or has “surface tension.” In the human body, this property allows water to provide protective barriers, cushioning, and friction reduction.

Once again, due to the polar nature of water molecules, these molecules “stick” to other surfaces, as long as the surface is also polar so that the rules of electrical attraction can be applied. In the human body this is crucial for water to stay in place. For instance, water lines the inner walls of blood vessels as a protective function. Water can do this because of adhesion.

Once again, due to the polar nature of water, it has thermal stability, meaning it takes more energy to change its temperature. When substances are exposed to energy, its molecules move faster, collide with one another and heat results. Because of the hydrogen bonds holding water molecules together, the increased movement is resisted, so it takes more energy to heat water. This is an important means for the human body’s ability to maintain a constant temperature range.

Many substance “dissolve” or dissociate in water. The more polar the substance is the more it will dissolve. Given the ionic nature of salts, they easily dissolve in water as the anions are attracted to the hydrogen end of the molecule and the cations the oxygen end. Water is also called the universal solvent.

Many substances react when water molecules are chemically added or removed. Hydrolysis is a catabolic process when water molecules are chemically added to a substance. Catabolism is the breaking down of a complex substance to simpler ones. Several digestion functions include hydrolysis processes.

Dehydration synthesis is an anabolic reaction. Anabolism involves the chemical combining of simpler substances to make more complex ones. When water molecules are chemically removed from a substance, a potential new bond can be formed for every molecule removed, allowing for the bonding of other substances leading to the formation of a more complex substance.