Match the term related to micturition with its description.
| Column I | Column II |
|---|---|
| (a) Stretch receptors on bladder wall | (i) The smooth muscle of the urinary bladder |
| (b) Detrusor muscle | (ii) A voluntary sphincter in the urethra |
| (c) External urethral sphincter | (iii) Send signals to the CNS when the bladder is filled with urine |
| (d) CNS | (iv) Passes on motor messages to initiate contraction of bladder muscles |