Urination, also known as micturition, voiding, peeing, and more rarely, emiction, is the process of disposing of urine from the urinary bladder through the urethra to the outside of the body. In healthy humans the process of urination is under voluntary control. In infants, elderly individuals and those with neurological injury, urination may occur as an involuntary reflex. In other animals, in addition to urination serving the purpose of expulsion of waste material, the act can serve to mark territory or express submissiveness. Physiologically, micturition involves coordination between the central, autonomic and somatic nervous systems. Brain centers that regulate urination include the pontine micturition center, periaqueductal gray, and the cerebral cortex.