How is urine formed?

The urine it's a liquid composed of water and substances separated by the body, and that has functions linked to the elimination of substances unnecessary for the body, or associated with electrolyte control, blood pressure and balance acid-base. Urine is secreted by the kidneys, is stored in the bladder, and is eliminated during urination.

Normal characteristics: color and smell

Among the most important characteristics of urine is its Colour, associated with the amount of water present in it: while the body that consumed a lot of water will have more transparent urine, in the more dehydrated bodies it is common that the kidneys tend to retain water in the body, causing the urine to have a more yellow color strong.

Eventually the urine may have an atypical color, which may be due to benign issues (such as the consumption of food of strong coloration) or by systemic diseases. When it is normal the urine does not have any odor, but on certain occasions it can have an unusual smell: like the color, it can be due to benign or minor issues, or to more or less serious diseases.

What is urine made of?

The body usually eliminates around Liter and a half of urine per day approximately. This number, however, is best explained when looking at the composition of the urine:

95% of urine is made up of water, while 2% is composed of Mineral salts (as chlorides, phosphates, sulfates, ammonia salts) and 3% of organic substances (urea, uric acid, hippuric acid, creatinine). Urine is one of the two main sources of water loss from the body, along with sweat.

How is urine formed?

The formation of urine is a process that consists of three stages:

1. Filtration. The blood that is carried by the afferent arteriole reaches the glomerulus, and the plasma solutes pass through the capillaries at a very high speed. Inside the glomerulus, metabolic waste is filtered, and small nutrients that will be discarded: the passage of a quantity of water gives rise there to the formation of a liquid, which is called filtrate glomerular.
2. Tubular reabsorption. The filtered fluid advances through the renal tubules, and there some of the substances are reabsorbed and incorporated into the blood again. Some of the substances that are reabsorbed are water, sodium, glucose, phosphate, potassium, amino acids and calcium.
3. Tubular discharge. A large part of the blood substances is transported from the blood plasma to the uriniferous space, while waste substances are produced from the tubular capillaries into the lumen of the tubule, in the zone distal.

Once formed, the liquid reaches the collecting tube where the only thing you can incorporate is a little more water, so it is not considered one more phase of the training. However, it is that place where the liquid acquires the name of urine, and is transported to the urinary bladder, where it will be stored until the urination reflex occurs.

Urine analysis

Due to the characteristics of urine it is that analysis that can be made of its composition are very useful: with a special strip of paper it can be made quickly an analysis that will show if there are abnormal products in the urine, of which the most common are the sugar, the protein or blood.

Diseases such as cystitis, heart disease, or different urinary or kidney infections can be detected through this type analysis, which also have the functionality of detecting the consumption of certain drugs that are eliminated through the urine.

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