Pharmacology All 5-HT receptors are heptahelical serpentine receptors EXCEPT: A 5-HT1 B 5-HT2 C 5-HT3 D 5-HT4 💡 Explanation All 5-HT receptors are heptahelical serpentine receptors EXCEPT: ✓ Correct Answer: C. 5-HT3