Which statement is correct regarding activation of receptors on the effector organs in the ANS?

Acetylcholine is the primary neurotransmitter used in the autonomic nervous system (ANS) and is known to bind to muscarinic receptors, which are a type of cholinergic receptor. These receptors are located on various effector organs, including the heart, smooth muscles, and glands. When acetylcholine binds to muscarinic receptors, it leads to various physiological effects, such as increased glandular secretions, bronchoconstriction, decreased heart rate, and contraction of smooth muscles.

The other statements do not correctly represent receptor activation mechanisms in the ANS. Adrenergic receptors are primarily activated by catecholamines such as epinephrine and norepinephrine, not acetylcholine. Additionally, nicotinic receptors are activated by acetylcholine rather than epinephrine, and muscarinic receptors are specifically associated with acetylcholine, not norepinephrine. Therefore, the correct understanding of ligand-receptor interactions highlights the role of acetylcholine in activating muscarinic receptors in the effector organs within the ANS.