Final answer:
The autonomic system causes the detrusor muscle in the bladder wall to relax as the bladder fills with urine.
Step-by-step explanation:
The process of urination is controlled by both the autonomic and somatic nervous systems. The autonomic system causes the detrusor muscle in the bladder wall to relax as the bladder fills with urine, but the conscious contraction of the detrusor muscle expels urine from the bladder during urination.
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