Pee is formed in the kidneys, where blood filtration takes place, which gives rise to it. In other words, pee is what doesn’t take advantage of blood. About 95% of it is water and the remaining 5% is a mixture of substances existing in excess in the blood and residues of cellular activities, mainly uric acid, urea and sodium chloride. An adult person does around 1 and a half liters of pee per day, but this volume varies according to the amount of water ingested, the temperature of the environment and the characteristics of each organism. Every time we go to the bathroom we pee, on average, 300 ml – just under a can of soda. In the infographic below, understand how the glass of water we drink turns into pee a few minutes later.
1. When we drink a glass of water, the liquid passes through the esophagus, stomach, is absorbed by the walls of the small intestine and then follows through the bloodstream until it reaches the kidneys, where part is absorbed and part is routed to the urinary system
two. Our kidneys (we have two) are shaped like a huge bean, 12 cm long, 7 cm wide and 5 cm thick. Each is made up of about 1 million filtering units, the nephrons. This is where pee is produced
– (Cassio Bittencourt)
3. Blood enters the nephrons under high pressure and undergoes the first filtration in the tangle of capillaries called the glomerulus. A good part of the liquid portion of the blood, the plasma, overflows through the vessels, forming the glomerular filtrate, a kind of “pre-pee”. In one minute, about 125 ml of plasma is filtered
4. Purified blood returns to the organism, while the «pre-pee» accumulates in Bowman’s capsule, a reservoir around the glomerulus. Then, little by little, this liquid makes its way through a complex tubular system
5. The “pre-pee” has waste from the body but also useful substances such as glucose, amino acids and mineral salts. As it flows through the capillaries of the nephron, these substances are reabsorbed and new waste products from the blood are secreted by the capillaries.
6. The fluid then passes into the collecting duct, the last segment of the nephron, where some of the water can be absorbed and returned to the blood. The amount of water absorbed depends on the body’s hydration level: the more water we drink, the less absorption and the more dilute the urine will be.
– (Cassio Bittencourt)
7. The pee is finally ready and goes to the bladder through the ureters, two tubes 20 to 30 cm long and the diameter of a straw. Its yellowish color is the result of the presence of urinary pigments, such as urochrome and urobilin, secreted by the liver.
8. In addition to storing pee, the bladder is responsible for pumping it out of our body. It can accumulate up to half a liter of liquid, but 300 ml is already enough to press the nerves that surround it and generate the desire to remove water from the knee.
9. When the brain is told by nerves in the bladder that the tank is full and needs to be emptied, a command is dispatched to the internal sphincter, a muscular ring at the outlet of the bladder. It opens, the bladder contracts and lets urine run its course.
– (Cassio Bittencourt)
10. For pee to be released, another valve, the external sphincter, located a little lower, also needs to open. But this sphincter is voluntarily controlled, that is, it is only opened when we want to. So we don’t wet our pants on the way to the bathroom.
11. The pee, finally, is eliminated through the urethra, the channel that passes inside the genitals of both sexes. The men’s is elastic and measures about 20 cm, while the women’s measures only 4 cm.