GI 2 general

Question 1

Describe role of M3 receptors

Answer 1

• M3 receptors in the GI smooth muscle are stimulated by Ach

–> PROMOTE SMOOTH MUSCLE CONTRACTION

• Acetylcholineesterase metabolizes Ach to help regulate response at neuromuscular junction

–> Acetylcholinesterase INHIBITORS will INCREASE MOTILITY

Question 2

describe role of D2 receptors

Answer 2

• D2 receptors are Pre-synaptic receptors that regulate the release of Ach
• stimulated D2 receptors PREVENT the release of Ach or neuronarl firing

–> NEGATIVE REGULATOR

–> STIMULATING THEM DECREASES MOTILITY

–> INHIBITING THEM INCREASES MOTILITY

Question 3

Describe Motilin receptors

Answer 3

• Motilin is a hormone
• Promotes gastric motility through activation of motilin receptors located on gastrointestinal smooth muscle

Question 4

Metoclopramide

Answer 4

• D2 ANTAGONIST

–> PROKINETIC AGENT (promotes motility)

• TX FOR: GERD, Impaired gastric emptying, dyspepsia, antimetic
• ADVERSE EFFECTS: ALTERED MOTOR FUNCTION (Parkinsonian sysmptoms

–> blocks dopamine receptors in the brain

Question 5

BETHANECHOL

Answer 5

• M3 Agonist –> Prokinetic agent (increase motility)
• TX for: GERD, gastroparesis
• Cholinergic side effects… think about it.

Question 6

Neostigmine

Answer 6

• AchE INHIBITOR –> prokinetic agent (promotes motility)
• TX for: non-obstructive urinary retention and abdominal distension
• Cholinergic side effects

Question 7

Erythromycin

Answer 7

• MOTILIN RECEPTOR AGONIST (prokinetic agent)

–> lot of antibiotics have the side effect of diarrhea

• TX for: Gastroparesis
• ADVERSE EFFECTS: erythromycin mediated side effects?