Urine, what is it?

How many times a day do you go? We did not notice too because urination is surely a habitual gesture and reflex. But has anyone ever wondered what exactly is happening in our urinary system before this urge to go make us bounce our chair ....
How urine is formed?

The urine is a yellowish liquid organic product in the kidneys (filtered from the capillary walls of renal arteries), stored in the bladder and excreted by the ureters during urination.

The nephrons are the fundamental units of the kidneys. There is on average one million nephrons in the kidney. Approximately 180 liters of blood were filtered daily at nephrons to obtain an average of 1.5 liters of urine per day.
The first phase of the formation of urine is glomerular filtration through the capillary wall of the afferent arteriole, giving the original urine. Normally, this filter only passes or proteins or blood cells (red cells, white cells, platelets). This primitive urine contains all the toxic waste from the body's metabolism.

In renal tubules:

Some solutes (such as glucose) and an amount of water is retained and recovered in the blood is called tubular reabsorption. This mechanism of reabsorption is regulated by hormones (ADH, aldosterone, cortisol, renin-angiotensin) and aims to maintain balance on the constants of the body (fluid balance, acid-base balance, ....). These solutes are reabsorbed into the needs of the body.

Additional waste is added to the urine conveyed in the renal tubules. It is tubular secretion. This phenomenon is to eliminate excess waste from the blood (not filtered by the glomeruli) in the kidney tubules.

Thus, the final urine is formed to be eliminated in the urinary tract. There is talk of urinary excretion.

All these mechanisms occur in the kidneys (nephrons specifically).

The final urine formed is collected and collected at chalices and pelvis of the kidney, to be forwarded to the ureters. It is first stored in the bladder and is then eliminated through the urethra during voiding.

The composition and role of urine ...

The final urine is normally composed of:

Water majority

toxic organic substances from the body and metabolic transformations: urea, creatinine, uric acid

inactive forms of ingested by the individual drugs (for medication)

ingested toxic substances (drugs, cocaine, heroin, cannabis ...)

ions and minerals: potassium and chlorine are in larger quantities, sodium, sulfates, phosphates, bicarbonates, calcium, magnesium ....

The main role is to carry urine metabolic and toxic waste, while retaining and recovering useful substances to balance the body. Thus, regulating the removal and retention of water and ions also vary depending on the internal balance of the body.

However, the composition of the urine can be changed according to the amount of hydration of the individual, according to his power. The composition of the final urine produced also depends on the composition of the filtered blood and filtration capabilities and reabsorption in the urinary tract.