Question

The reflexive actions to control micturition and defecation are very similar. Both are initiate by stretch receptors in the walls of the storage organs, namely the _____________ for urine and the _____________ for feces. Those receptors signal autonomic neurons in the ___________ level of the spinal cord which cause the ________________ urethral and anal sphincters to relax and the muscular walls of the storage organs to contract. The rectal wall does not have a specific name, but the ______________ muscle is found in the wall of the bladder. Both systems have an external sphincter of _____________ muscle tissue that can be voluntarily controlled when the time is not appropriate for elimination of waste. The urinary system, however, can overcome that voluntary control through autonomic activity to avoid urine backing up to the kidneys which would result in renal failure.

Answer 1

Answer

The reflexive actions to control micturition and defecation are very similar. Both are initiate by stretch receptors in the walls of the storage organs, namely the urinary bladder for urine and the rectum for feces. Those receptors signal autonomic neurons in the S2 - S3 level of the spinal cord which cause the internal urethral and anal sphincters to relax and the muscular walls of the storage organs to contract. The rectal wall does not have a specific name, but the detrusor muscle is found in the wall of the bladder. Both systems have an external sphincter of skeletal muscle tissue that can be voluntarily controlled when the time is not appropriate for elimination of waste. The urinary system, however, can overcome that voluntary control through autonomic activity to avoid urine backing up to the kidneys which would result in renal failure.