WHAT ARE THE WAYS OF ELIMINATING WATER IN HUMANS? - ANATOMY AND PHYSIOLOGY - 2025

The main routes of elimination of water in humans are the urethra, in the urinary system; the anus, in the digestive system; and pores on the skin. Urine is discharged through the urethra, feces through the anus, and sweat through the pores.

The mechanism of water elimination in humans is an act of internal regulation of fluids that maintains the balance of electrolytes in healthy concentrations for the body, as well as maintaining the necessary volume of water.

The principle of this fluid balance in the human body works as follows: the amount of water that a person expels must be the same amount of water that the person must ingest. Thirst and the urge to ingest mineral salts act as an indicator mechanism that you need to drink water and replenish electrolytes.

Taking into account that the elimination of water is a process, either physiological impossible to avoid or totally involuntary, drinking water for humans is one of the most important and necessary voluntary activities for good health and life itself, if not the of greater importance.

A human being can survive for up to five weeks without food to eat, but only about four or five days without water. Liquids and food are the main ways to consume precious water for the body.

The most common routes for the elimination of water in humans

1- urination

It is the act or process of eliminating urine and the mechanism of greater regulation and expulsion of water that the body has.

The kidneys are responsible for filtering the blood of impurities that are then directed as waste in the form of liquid to the bladder. Once it is full, the person feels the need to release it from the toxic load, and it does so through the urethra.

Most waste in urine comes in the form of nitrous proteins like urea and creatinine. They are eliminated via the urine after a process of filtration, reabsorption and secretion that occurs in the kidneys.

The body has about three liters of blood and the two kidneys filter about 180 liters of blood per day (125 ml / min). This volume is filtered between 50 and 60 times a day, but only one or two liters are excreted in the urine each day.

In this way, the kidneys are essential to maintain the balance of the volume of water in the body and the saline composition of the fluids inside; expelling excess water along with filtered toxins from the blood.

2- defecation

It is the act or process of elimination of feces, with which the body gets rid of the undigested part of the solid material that was previously eaten as food.

The food bolus, once processed and released by the stomach, passes in the form of a semi-solid pasty mass (called chyme) to the duodenum, where the bile secretions from the liver break down harmful substances and process fats.

Then the chyme continues its way through the rest of the small intestine, which absorbs the necessary nutrients along the way. The increasingly solid mass is transported to the large intestine as waste. Finally it reaches the rectum, where it is ready to be expelled as fecal matter through the anus.

This entire process requires fluids to help both transport food throughout the digestive and intestinal tracts, as well as for the secretion of essential substances for digestion, decomposition and transformation.

Therefore, in the feces, which are semisolid, about 100 to 200 milliliters of water are eliminated from the human body per day, which added to the volume eliminated in the urine is equivalent to between 1,200 to 2,200 ml of water daily.

This volume of water eliminated in the feces can increase dramatically in case of diarrhea, 5 to 7 times more. For this reason it is highly recommended to maintain the ingestion of water and mineral salts and thus help the body to maintain that balance mentioned above.

3- perspiration

It is the process of sweat production as a mechanism of the human body for regulating its own temperature. It is also called sweating. Sweat is usually 99% water with a pH between 5 and 7, 0.5% minerals such as potassium and salts, and 0.5% organic substances such as urea.

It is produced in the dermis of the skin by the sweat glands and expelled through the skin pores. This fluid comes from the water located between the cells of the internal tissues of the body, called interstitial fluid, which is filtered by the ball of the sweat glands.

For sedentary people, its production is very low in moderate ambient temperatures, around 300 ml a day, but it can rise to several liters a day due to intense physical activities, high temperatures in the environment and / or high levels of humidity, exceeding 2, 6 liters.

Both water and mineral salts are eliminated in this process, therefore it is very important to maintain the hydration of the body and the consumption of food after having sweated for a long time, and thus maintain the balance already described at the beginning of the article.

In the process of releasing energy in the form of heat during physical exercise, the evaporation of the sweat produced is the most efficient way for the body to regulate the temperature and release it of calories. One liter of sweat evaporated at 30 ° C is equivalent to 580 kcal burned.

Under normal conditions, a human being eliminates about 300 ml of water per day in the form of sweat. Added to those eliminated by urine and feces, the average water elimination is approximately 2,500 ml per day, which should be the same amount of water that should be ingested daily by a person.

Other ways to eliminate fluids

The human body also releases water: in the form of steam in the breath when we exhale and in the form of saliva when we spit or cough or sneeze. Women additionally eliminate fluid in vaginal secretions.

Despite being also considered elimination mechanisms, the volume of water expelled is very low compared to the three main ones.

References

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