Micturition, also known as urination, is the process of emptying urine from the bladder through the urethra to the outside of the body_Reflex). It is the urinary systems form of excretion. Micturition is a complex mechanism that involves coordination by the sympathetic, parasympathetic, and somatic nervous systems, and it is the higher centers within the brain that allow for urination to occur at the right time_Reflex). The micturition reflex is triggered when the bladder fills with urine, and the detrusor muscle remains relaxed until the bladder fills to about 250 mL with urine_Reflex). During micturition, parasympathetic stimulation causes the detrusor muscle to contract and the internal urethral sphincter to relax. The external urethral sphincter (sphincter urethrae) is under somatic control and is consciously relaxed during micturition. In infants, voiding occurs involuntarily (as a reflex), but the ability to voluntarily inhibit micturition develops by the age of 2–3 years, as control at higher levels of the central nervous system develops. The volume of urine in the bladder that normally initiates a reflex contraction in adults is about 300–400 milliliters (11–14 imp fl oz; 10–14 US fl oz) .

In summary, micturition is the process of emptying urine from the bladder through the urethra to the outside of the body. It is a complex mechanism that involves coordination by the sympathetic, parasympathetic, and somatic nervous systems, and it is the higher centers within the brain that allow for urination to occur at the right time.