Identify the following structures and explain that significance in renal physiology?
(c) Sphincters in the bladder

Explanation

(c) Sphincters in the bladder:
1. The external and internal sphincters are muscles guarding the opening of the urinary bladder at the urethra.
2. When the urinary bladder gets filled with urine, the urinary bladder stimulates the central nervous system via sensory neurons and brings about contraction of the bladder. Simultaneously somatic motor neurons induce the sphincters to close.
3. Smooth muscles contract resulting in the opening of the internal sphincter passively and relaxing the external sphincter. When the stimulatory and inhibitory controls exceed the threshold, the sphincter opens and urine is expelled out.
4. Thus the sphincter muscles keep the urethral closed except during expulsion of urine. Thus the sphincter muscles keep the urethra closed except during expulsion of urine.