Which of the following is the ONLY organ that receives ONLY sympathetic innervation (no parasympathetic supply) from the ANS?

• A Heart (SA node)
• B Adrenal medulla
• C Parotid salivary gland
• D Blood vessels (systemic arterioles) ✓

Explanation

Most systemic arterioles and veins receive only sympathetic (adrenergic) innervation and have no parasympathetic supply. Vasoconstriction occurs via alpha-1 receptors; vasodilation in some vascular beds (e.g., skeletal muscle) is via beta-2 receptors or cholinergic sympathetic fibers. The heart receives both sympathetic (accelerator) and parasympathetic (vagal) innervation. The adrenal medulla receives preganglionic sympathetic fibers but this is a ganglion, not an effector organ per se. Salivary glands receive both autonomic divisions.

Reference: Guyton & Hall, Textbook of Medical Physiology, 14th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.