Relaxation of the detrusor muscle to enhance bladder filling can be facilitated by administering a medication that will PREVENT stimulation of the:

• A. Alpha-adrenergic receptors.
• B. Beta-adrenergic receptors.
• C. Cholinergic receptors.
• D. Serotonin receptors.

Answer: (C)

Acetylcholine acting on muscarinic receptors on the detrusor muscle triggers contraction. To enable bladder filling, you want the detrusor to stay relaxed, which is achieved by blocking these cholinergic (muscarinic) receptors. An antimuscarinic medication prevents acetylcholine from stimulating the detrusor, reducing contraction and allowing the bladder to expand and fill. Other receptor targets exist (beta-adrenergic stimulation can also promote relaxation, and alpha effects influence outlet resistance), but the mechanism asked about is blocking cholinergic stimulation to stop detrusor contraction.