How is urine formed?

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

Normal characteristics: color and odor

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

Eventually the urine may have an atypical color, which may be due to benign issues (such as the consumption of strongly colored foods) or due to systemic diseases. When normal urine has no odor, but on certain occasions it may have an unusual smell: like the color, it may be due to benign or unimportant issues, or to more or less serious illnesses.

What is urine made of?

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

95% of urine is made up of water, while two% It is composed of mineral salts (such as chlorides, phosphates, sulfates, ammoniacal 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, next to sweat.

How is urine formed?

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

  1. Filtration. The blood that is transported by the afferent arteriole reaches the glomerulus, and the plasma solutes pass through the capillaries at a very high rate. Within the glomerulus, metabolic residues and small nutrients that will be discarded are filtered: the passage of a quantity of water gives rise to the formation of a liquid, which is called glomerular filtrate.
  2. Tubular reabsorption. The filtered liquid moves 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. tube secretion. A large part of the blood substances are transported from the blood plasma to the uriniferous space, while the waste substances are produced from the tubular capillaries towards the lumen of the tubule, in the distal area.

Once formed, the liquid reaches the collector tube where the only thing you can incorporate is a little more water, so it is not considered another phase of 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 the urine is that the analysis that can be made of its composition are very useful: with a special strip of paper an analysis can be quickly made that will show if there are abnormal products in the urine, of which the most common are sugar, protein or blood.

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