CVS Practice Test 2025 - Free CVS Practice Questions and Study Guide

The release of norepinephrine typically occurs in most sympathetic responses, but there are specific instances where acetylcholine (ACh) is released instead. In the case of sweat glands, these are primarily under the control of the sympathetic nervous system, and rather than norepinephrine, they utilize acetylcholine as their neurotransmitter. This is unique among the effector organs of the sympathetic nervous system, as most such glands respond to norepinephrine.

Sweat glands, specifically the eccrine type, respond to ACh to stimulate sweat production, which plays a vital role in thermoregulation. This distinguishes them from other glands that operate through norepinephrine, making them an exception in this context.

The other options listed—salivary glands, endocrine glands, and sebaceous glands—do not primarily function with ACh in response to sympathetic stimulation. Instead, salivary glands respond to parasympathetic stimulation and various hormones, endocrine glands release hormones into the bloodstream rather than responding directly through ACh, and sebaceous glands are controlled by androgens and sympathetic stimulation typically involves norepinephrine. Therefore, sweat glands are the only ones where ACh is significant for their activation.