The science behind dehydration

by Xypher Pino

You can only survive for about a week if you do not drink water. You need to drink lots of water if you want to be healthy. You have definitely heard these statements before – maybe from your parents, friends or online. Bottom line is, we all know how important water is and how we need it to survive. However, not a lot of people know about the science behind water and dehydration. Why can our body only go for so long without it and what goes on in our body when we are dehydrated?

The body is made of about 60 percent water. These fluids are involved in many functions occurring inside the body – digestion, absorption, circulation, nutrient transport and temperature maintenance. Once you lose about 3 percent of that water, you will become dehydrated. When this happens, osmoreceptors located in your hypothalamus, the part of the brain responsible for homeostatic activity, will detect lower levels of plasma solute concentration in your blood. Osmoreceptors are nerve cells that have proteins and plasma membranes that water can pass through by the process of diffusion, the movement of molecules from a high to low level concentration. Whenever you are dehydrated, these cells shrink in size, which prompts the posterior pituitary gland, an organ of the endocrine system, to release the antidiuretic hormone, or ADH. ADH is a hormone that acts on the kidneys and is responsible for regulating water and balancing electrolytes. Increased levels of ADH causes the kidneys to reabsorb more water back into the blood and as a result, less urine is produced.

Urine excretion is one of the main ways that the body rids itself of harmful wastes, such as ammonia. When you are dehydrated, your body will decrease the production of urine, which means that your body will become overconcentrated with urea, a substance produced by the liver which contains ammonia. This can lead to gout, a swelling of the joints, and kidney stones, hard deposits of minerals that can clog the urinary tract. Also, because you have less urine,
you will urinate less frequently which will cause build-up of bacteria that causes urinary tract infections, such as E. coli. Essentially, water is crucial in maintaining homeostasis in your body. Without adequate mounts of liquid, your body cannot rid itself of waste properly, resulting in various medical problems.

Water also assists in electrolyte balancing. Electrolytes are minerals found in the body, such as sodium and calcium, which cells need to function properly. These electrolytes have either a positive or negative charge when they are dissolved in water. Because of the charges, electrolytes are required in regulating chemical reactions in the body. For example, neurons in the brain can transmit signals to one another through the use of sodium and potassium. Based on the amount of water in the body, electrolyte levels can become too low or too high. It is important to prevent dehydration and keep drinking water to maintain electrolyte homeostasis, as an imbalance of it can cause headaches, fatigue, nausea, vomiting and diarrhea. In severe cases, seizures, comas and rhabdomyolysis, or the breakdown of muscle tissue, can even occur.

This is what occurs in your body when you are dehydrated. According to research, men should intake about four liters of water per day while women should intake about three liters. Now that you know the science behind water and dehydration, take a sip of your water and remember to always stay hydrated.


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