Final answer:
The micturition reflex involves the stimulation of stretch receptors in the bladder wall, activation of parasympathetic motor neurons, relaxation of the internal sphincter, and conscious relaxation of the external sphincter to allow for bladder emptying.
Step-by-step explanation:
The micturition reflex is a process involved in urination, controlled by both the autonomic and somatic nervous systems. When the bladder fills, stretch receptors in the bladder wall send impulses to the sacral region of the spinal cord, stimulating parasympathetic motor neurons that control the detrusor muscle to become active. This causes the detrusor muscle to contract and the internal sphincter to subconsciously relax. Simultaneously, through conscious control, the external sphincter can be relaxed to allow for bladder emptying.