Final answer:
The micturition reflex involves the activation of important spinal nerve roots, namely the sacral nerve roots, which transmit nerve impulses from the bladder wall to the sacral region of the spinal cord.
Step-by-step explanation:
The micturition reflex involves the activation of various nerve roots in the spinal cord. The important spinal nerve roots in the micturition reflex are the sacral nerve roots. They transmit nerve impulses from the stretch receptors in the bladder wall to the sacral region of the spinal cord, which then generate a spinal reflex responsible for bladder emptying. In addition to the sacral nerve roots, other nerves involved in the control of urination include the hypogastric and pelvic nerves.