Micturition

Micturition is the term for expulsion of urine from the bladder. it normally is a reflex activity stimulated by stretch receptors in the bladder wall that respond to distension of the urinary bladder created by the constant inflow of urine by way of the ureters.

Figure 23-6. Transitional epithelium. A) Bladder full, wall distended. B) Bladder empty, wall relaxed.

which in turn relax the smooth muscle sphinc­ter in the neck of the bladder and contract the muscle wall of the urinary bladder by way of sacral parasympathetic nerves. However, reflex emptying of the bladder can be prevented by voluntary suppression of the reflex and control of the m. urethralis surrounding the proximal urethra.