Water and Salt

Water and salt are very important to help body homeostasis. Water takes up 60 to 80% of the volume of most living cells. It has a very high hear capacity. It can remain at one constant temperature while absorbing and releasing large amounts of heat. This helps prevent sudden changes in temperature throughout the body from external forces, such as the sun or wind. This ensures temperature homeostasis. Water also has a high heat of vaporization. This helps when the human body sweats. When we sweat, we lose large amounts of heat. Water is also known as the universal solvent. Water molecules orient themselves with their negative ends toward positively charged solutes. First they attract them and then surround them. This is why ionic compounds dissociate in water and form true solutions. Water also forms hydration layers. These hydration layers surround large charged molecules like proteins and shield them from the effects of other charged substances. It also prevents them from settling out in the solution. Thee protein water mixtures are called biological colloids. Water is also an important reactant in many chemical reactions. For example, water helps to digest food. These reactions are called hydrolysis reactions. Water molecules are also removed from every bond formed from large carbohydrate or protein molecules which is called dehydration synthesis. Finally, water is cushioning. Waters cushion like quality protects certain organs from physical trauma. The ionic compound, salt, is also necessary to maintain homeostasis. Salt contains cations and anions and dissociates in water. This allows water to overcome the attraction between oppositely charged ions, called electrolytes. Salt is also used to build hard bones and teeth. Salt in its ionized form is also essential for nerve impulse transmission and muscle contraction.