What is the function of the bladder in the human body?

The bladder's primary function in the human body is the storage of urine. It serves as a reservoir that collects urine produced by the kidneys before it is excreted from the body. The bladder can expand as it fills with urine, allowing for a significant volume to be accommodated. Once the bladder reaches a certain volume, nerve signals prompt the urge to urinate, leading to the voluntary release of urine through the urethra. This function is essential for maintaining urinary continence and regulating the excretion of waste products from the body.

The other options relate to different bodily functions: waste filtration is primarily the role of the kidneys, regulation of blood pressure involves various systems including the cardiovascular and hormonal systems, and the absorption of nutrients occurs mainly in the gastrointestinal tract, particularly in the intestines.