Integrated physiology of the lower urinary tract

Abstract

Introduction The urinary bladder and its outlet, the urethra, serve two main functions: (1) storage of urine without leakage and (2) periodic release of urine. These two functions are dependent on central as well as peripheral autonomic and somatic neural pathways.1-6 Since the lower urinary tract switches in an all-or-none manner between storage and elimination of urine, many of the neural circuits controling voiding exhibit phasic patterns of activity rather than tonic patterns occurring in autonomic pathways to other viscera. Micturition is also a special visceral mechanism because it is dependent on voluntary control, which requires the participation of higher centers in the brain, whereas many other visceral functions are regulated involuntarily. Because of these complex neural regulations, the central and peripheral nervous control of the lower urinary tract is susceptible to a variety of neurologic disorders. This chapter will summarize clinical and experimental data to describe the complexity of the peripheral and central nervous systems controling urine storage and elimination in the lower urinary tract.