Water (H2O) is so essential that humans can die from dehydration, within a matter of a few days, if they are completely deprived of it.
Health experts recommend drinking six (6) to eight (8) glasses each day, along with other drinks.
This is, however, a general average and in some cases an individual may require more than eight glasses per day. It depends on the individual's body mass index (BMI), and the amount of fluid loss due to physical activity or health conditions such as kidney stone.
It is estimated that many people do not drink enough water and are, consequently, slightly dehydrated. This can result in symptoms such as headaches, irritability and forgetfulness. It can also place a strain on the kidneys and result in urinary tract infections and kidney stones. The thirst sensation of older persons can diminish and hence the elderly are at particular risk of dehydration, as are small children.
Even before birth, fluids play an integral part in our sustenance and development. We consume it from our mothers and spend many months floating in amniotic fluid. At birth, as much as 75% of a baby's weight is made up of water. As we grow older, however, this tends to decrease. For example, in young adult male it accounts for an average of 55% to 60% of body weight while women average slightly less. Obese and elderly persons can average as low as 45%.
As we continue to grow and develop after birth, fluids are continually exchanged between compartments within our bodies, by way of capillary walls and plasma membranes. Water moves by osmosis from the digestive tract to the bloodstream. It is then distributed from the blood to the tissue fluid by a process known as capillary filtration. Osmosis from one fluid compartment to another is determined by the relative concentration of solutes in each compartment. The direction of osmosis, therefore, will be from a more dilute solution to a more concentrated one.
A person is said to be in a state of water-balance when daily gains and losses are equal. Losses occur daily in urine, faces, breathing, sweat, and cutaneous transpiration. Cutaneous transpiration is not the same as sweat. A simple way to observe it is to place the palm of your hand on a cool nonporous surface, such as a mirror. When you remove your hand, you will notice the condensed water that transpired through the skin, on the surface of the mirror.
H20 is the chemical formula for water. This composition is simply two (2) hydrogen atoms bonded to one (1) oxygen atom.
Basically, H2O helps to maintain the right volume and concentration of blood and other fluids within the body, but its comprehensive function extends a bit beyond this. It contains a set of properties that facilitates proper biological functions. These properties include solvency, cohesion, adhesion, chemical reactivity, and thermal stability.
Solvency is the ability to dissolve other chemicals. Water is sometimes referred to as the universal solvent because it dissolves a broader range of substances than any other liquid. This is very important since biological molecules within the body must be dissolved in order to move freely, bond together, and perform their functions.
Adhesion is the tendency of one substance to cling or bind to other substances. This is different from cohesion, which is the tendency of molecules of the same substances to cling to each other. Adhesion forms a lubricating film on membranes within the body that helps reduce friction. An example of this is when the lungs and heart contract and expand and rub against these membranes.
Chemical reactivity is the ability to participate in chemical reactions - many chemicals such as acid and salt are ionized. Thermal stability is the ability to help stabilize the internal temperature of the body.
Fluid intake is governed mainly by thirst. The body is in a state of fluid imbalance if there is abnormal fluid concentration, fluid volume, or fluid distribution among different compartments in the body. Fluid deficiency occurs when output exceeds intake, over an extended period of time. There are two kinds of deficiency - volume depletion and dehydration.
Volume depletion is known as hypovolemia and occurs when proportionate amounts of H2O and sodium are lost without being replaced. This occurs mainly in cases of hemorrhage, burns, chronic vomiting, or diarrhea. A less common cause is aldosterone hyposecretion (Addison disease), which results in inadequate sodium and water reabsorption.
Dehydration is different from volume depletion in that the body eliminates significantly more H2O than sodium. The most common cause of dehydration is simply not drinking enough fluids. Other causes include diabetes mellitus, ADH hyposecretion (diabetes insipidus), and profuse sweating. It should be noted that prolonged exposure to cold weather can be a cause of dehydration, just as much as prolonged exposure to hot weather.
The most serious effect of volume depletion and dehydration are circulatory shock, due to loss of blood volume and neurological dysfunction, due to dehydration of brain cells.
Fluid excess is less common than fluid deficiency. This is so because the kidneys are very effective at compensating for excessive fluid intake, by producing more urine. This is one of the main functions of the kidney. When the kidneys are not functioning properly, however, this usually leads to excessive fluid retention.
Fluid excesses are of two types - volume excess and hypotonic hydration. With volume excess, both H2O and sodium are retained. This is commonly caused by renal failure. With hypotonic hydration (also called water intoxication), more water than sodium is retained or ingested. Fluid excesses can result in pulmonary or cerebral edema (or oedema) which is the gathering of fluid in the lungs or brain.
Filters and other purification systems have become increasingly popular in recent years. While most of these purification devices are able to remove some pollutants, unfortunately they can also remove compounds such as minerals that may be beneficial to health. Bottled-waters are widely available and are a popular alternative. Although most of them are safe to drink, they are not all necessarily free of compounds and additives.
H2O is essential for biological functions and must be continuously replenished, as it is constantly lost mainly through urination, respiration, and sweating. Having the correct quantity and quality are very important. An average adult requires between two (2) to three (3) liters daily, depending on body size and weight. Persons with kidney stones, severe diarrhea, or any bout of sickness where dehydration poses a particular risk should drink plenty of fluids and water, especially in frequent sips.
How many glasses have you had today? Why not have a refreshing glass right now?