Final answer:
The adrenal medulla, sweat glands, and most blood vessels are innervated only by the sympathetic system. The adrenal medulla releases hormones like epinephrine and norepinephrine, while sweat glands use ACh instead of the typical norepinephrine for the sympathetic system. Blood vessels are primarily under sympathetic control affecting blood pressure.
Step-by-step explanation:
The adrenal medulla, sweat glands of the skin, and most blood vessels are innervated only by the sympathetic system. While most of the autonomic nervous system provides dual innervation, these organs and tissues are exceptions. The adrenal medulla is a part of the sympathetic nervous system, producing epinephrine and norepinephrine in response to stimulation. On the other hand, sweat glands receive sympathetic fibers but use acetylcholine (ACh) as a neurotransmitter, activating muscarinic receptors to produce sweat. This is a deviation from the usual sympathetic response where norepinephrine is the primary neurotransmitter. Blood vessels, especially those in systemic circulation, receive sympathetic innervation which controls their constriction and dilation, hence affecting blood pressure.