Primary action of nitric oxide in the GIT – Physiology MCQ

Which among the following is the primary action of nitric oxide in the GIT?
A. Contraction of gastrointestinal smooth muscle
B. Relaxation of gastrointestinal smooth muscle
C. Vasodilation
D. Vasoconstriction

Correct answer : B. Relaxation of gastrointestinal smooth muscle

nitric oxideNitric oxide molecule

Action of nitric oxide in the GIT

  • Nitric oxide (NO) is produced by the action of Nitric Oxide Synthase (NOS) on L-arginine
  • It acts as an inhibitory neurotransmitter in the gastrointestinal system (other inhibitory neurotransmitters are VIP and PACAP)
  • It does not have a membrane bound receptor
  • It diffuses into the target cells and activates guanyl cyclase
  • Activated guanyl cyclase produces cGMP from GTP
  • cGMP in turn, mediates smooth muscle relaxation

 

Related Posts