The bladder (Latin Vesica urinaria) belongs to the group of urinary organs (kidney, ureter, urethra), which are responsible for the formation and excretion of urine (urine). Via the urine, the body gets rid of numerous metabolic endproducts, including e.g. Urea (urea cycle, end product in amino acid synthesis), uric acid (purine metabolism) and small amounts of bilirubin (degradation product of hemoglobin). Also excess water can quickly be released again by an organism through urinary organs, for example if we absorb a lot of water in a short time.
On average, humans emptying the bladder 4-5 times a day (also called micturition), with between 200 and 500 ml each. The total amount dispensed per day is u.a. Depending on the water supply, the physical activity (sweating), outside temperature and even the time of day (at night less urine production).
Structure / position / anatomy of the bladder
The bladder sits on the pelvic floor. From the kidneys, small amounts of urine constantly flow into the urinary bladder via the two ureters. At the lower end of the bladder, where it enters the urethra, two closing muscles prevent uncontrolled urination. The bladder contains pressure receptors that signal to the brain that urine must be released as the amount of filling increases. The brain then signals to us a steadily more intense urinary urgency, that is, what we feel as a full bladder.
To a certain extent, the bladder can expand (about 1.3 liters of urine, but individually very different). This is made possible by the surrounding muscle tissue of the bladder. From inside, so-called urothelial cells dress the bladder. This special cell tissue prevents diffusion of fluid through the membrane, because the fluid should be excreted, and not be taken up again by the body.