Abstract
With respect to five established principles in conventional anatomy or physiology of the urinary bladder and urethra, the following revisions were proposed from the viewpoint of physics and ultrasound: (1)Throughout urinary storing and micturition, only involving action from the motor neurons into the bladder may be an on-off switching between two steps of bladder property as a material. (2)The weight of the bladder (thickness of the bladder wall) varies quickly and dynamically with the change in the stress necessary for contraction (urethral resistance). (3)The main function of the urethra may not be the closure during storing but rather opening during micturition, and this opening function may control the overall micturition behavior. (4)The male urethra is surrounded by a long-ranged muscle unit throughout the prostate. The so-called “external sphincter muscle” described in current anatomy is no more than the caudal end of that muscle unit. (5)The bladder may absorb a considerable amount of water from the urine inside it, at least while sleeping.
