Water is the most common and important fluid in the body. It helps perform many different functions such as cell nutrition, nutrient transport and waste removal. Water metabolism and electrolyte balance are closely linked to normal functioning of vital organs.
The intracellular and extracellular fluids are essential to health and homeostasis(State of equilibrium) . Intracellular fluid (ICF) is the compartment that includes all fluid enclosed within cells by their cell membranes. Extracellular fluid (ECF) is the surrounding fluid that surrounds all cells in the body. These fluids are broken down into several categories: plasma, lymphatic fluid, interstitial fluid and synovial fluid.
Intravascular fluid refers specifically to the liquid portion of blood that goes inside the body’s arterial system. Interstitial tissue consists mainly of a number of microscopic spaces between all cells (in-between spaces around cells of a tissue). Plasma carries oxygen and nutrients to each and every cell. It also facilitates maintenance of blood pressure, lubrication of joints and tissues, physical performance, cell function like protein synthesis.
The removal of water from the body through natural processes such as urination, defecation, perspiration, and exhalation serves important physiological purposes. As a result, it is essential to replace water exogenously. If water intake falls short of replacing the fluid lost through these critical metabolic functions over an extended period, the body risks dehydration, which can be fatal if left untreated. It is common knowledge that humans cannot survive without oxygen, water, and food.
Major amounts of water is utilised for vital functions such as Waste removal, Thermoregulation, humidification of air exhaled from lungs.
Waste Removal : The accumulation of metabolic wastes within the body can be detrimental to its overall health, which is why it is crucial for normal physiological functioning to eliminate these waste products.
Thermoregulation : To maintain a specific temperature (roughly 37 degrees Celsius) in the human body, the process of thermoregulation utilises water to dissipate heat and cool the body. Sweat glands in the skin release water, which evaporates from the skin surface, resulting in the body being cooled.
Humidification of air : As we exhale, our lungs release carbon dioxide into the air, and our breath includes moisture. Since carbon dioxide is a harsh gas and it can be tough on the nasal cavity of the nostrils.The presence of moisture in our mouth and lungs means that every breath we exhale contains a small amount of water in the form of water vapour.
Hypothalamus in our brain has its duty to keep track of the concentration of fluid balance in the body. The blood plasma inside our body is a mixture of electrolytes, hormones, enzymes, minerals, proteins, etc. Tracking the concentrations of the fluid is done by the communication that happens from time to time among the hypothalamus, osmoreceptors, baroreceptors, hormones and enzymes.
In the hypothalamus, the thirst centre manages the requirement of water with the help of osmoreceptors. The function of osmoreceptors is to detect the changes in the osmolarity of the fluid.
Osmolarity refers to the concentration of solute and solvent in a solution. In the biological system, the electrolytes are the solute particles and fluid is the solvent in the solution, that is plasma. The solute is always transferred from the portion of high osmolarity to the portion of low osmolarity through the semipermeable membrane of the cell.
Water is removed from the intravascular fluid of the body for the above physiological functions, thus change in osmolarity is detected by the osmoreceptors in the hypothalamus and produces the urge to drink water. This autoregulation is termed as Thirst Mechanism.
The process is so efficient and finely tuned that it allows the exact amount of water we actually need at that point of time. Body refuses once it is saturated to the needed quantity. It is experienced by the pet owners, that the pet drinks according to the urge generated by its brain. No animal in the world has died due to dehydration, unless it fails to drink water due to non availability.
The conventional wisdom backed by made up theories suggests ‘x’ amount of water must be consumed in ‘x’ intervals is actually misleading and disturbing the normal function of our body. That is how we are disrupting our physiological function. A labour working under the straight sun over the mid head, drinks water as per his thirst sensation. We never see a worker who falls due to dehydration. Because the innate cellular intelligence can utilise the available water accordingly by the requirement of water outside. If we do not ingest water after feeling thirsty, due to lack of water availability, the body preserves the fluid by not sweating or minimising the urine dispense till we replenish by the ingesting water and it can survive for hours.
People are widely exposed to these intellectual calculations and believe the same. If we need to make a decision on water ingestion, why has nature implanted the sense of urge to drink water?
Following these calculated terms, we are now either MALHYDRATED or OVERHYDRATED. Over hydration also has a problem and can lead to death, if not identified. When a person sweats more, the liquid and electrolytes are lost. Ingesting only water can make a big difference in fluid osmolarity. That is, the amount of liquid falls short compared to the solute(salt particles), leading to a pathological condition called HYPONATREMIA. Unfortunately the symptoms in this state are very similar to the dehydrated condition. Ingesting only water can worsen the situation and cause death. Drinking water as per thirst is the best practice. Trusting our cellular intelligence is not a dumb act. Because of which we have been evolving for 6 million years. Thirst is not a delayed Indication.