bladder

The bladder is a hollow, elastic organ in the pelvis that stores urine produced by the kidneys. It can expand and contract depending on the amount of urine it contains. When the bladder fills, nerve signals prompt the urge to urinate. During urination, the muscles of the bladder tighten, and the sphincter muscles relax, allowing urine to flow out through the urethra. The process is coordinated by the nervous system to control when and where urination occurs. The bladder plays a vital role in waste elimination and maintaining fluid balance in the body.