Gastrointestinal · Physiological mechanisms of GI motility from swallowing to defecation; neural and mechanical control; pathophysiological mechanisms of dysmotility
By completing this question set, you will be able to trace the neural and mechanical events of normal swallowing through all three phases, identify the key manometric patterns that distinguish motility disorders from mechanical obstruction, and explain how LES resting tone is maintained and what disrupts it. You will explain the role of interstitial cells of Cajal as the gastric pacemaker, describe the slow wave and action potential relationship, and explain gastric receptive relaxation and emptying regulation. You will explain the migrating motor complex (MMC) — including which hormone initiates phase III and why MMC disruption leads to bacterial overgrowth. You will trace the complete defecation reflex arc, explain the rectoanal inhibitory reflex (RAIR) at the neurotransmitter level, and predict the consequence of absent ganglia in Hirschsprung's disease. You will classify diarrhea into its four mechanistic categories and apply the osmotic gap formula to distinguish secretory from osmotic causes.