PHRM 311 Lecture Notes - Ondansetron, Morphine, Peristalsis
Document Summary
Pharmacology of the enteric nervous system (part 2) Secretions in coordination with motility are important in digestion of food particles, lubrication, nutrient absorption, regulation of ph and solute concentration, and elimination of waste products. Mediate relaxation of the intestine through a1, and in some cases a2b receptors. Antagonists at a1 receptors can enhance the release of acetylcholine or tachykinins from myenteric ganglia. Blockade of propulsive peristalsis causes delay in gi transit constipation. May block propulsive motility by evoking tonic spasms. Mechanism: acetylcholine release by activation of mu, delta and perhaps kappa receptors. Importance: accounts for significant constipating effect of opioid analgesics (morphine and codeine) management issue in chronic pain therapy. Slows intestinal transit, intestinal water absorption, resting sphincter tone. Adverse effects: constipation, abdominal cramping, dry mouth, nausea. Neurotransmitter serotonin histamine gastrin somatostatin cholecystokinin (cck) secretin. Released into the blood stream from the gastrin-producing (g) cells in the antrum of the stomach in response to food.
