Gastrointestinal physiology

Abstract This chapter outlines gastrointestinal physiology relevant to the MRCEM Primary examination. It describes the structural organization of the GI tract, including mucosa, submucosa, muscularis externa, and serosa. It details salivary gland function, control of swallowing, and oesophageal sphincter physiology. Gastric functions, secretory control, mucosal protection, and mechanisms of gastric emptying are reviewed. Small intestinal anatomy and villus structure are explained, alongside nutrient digestion and absorption processes for carbohydrates, proteins, fats, calcium, and iron. The chapter also addresses bile, bicarbonate, and water handling in digestion. All of the information maps to the RCEM Basic Sciences syllabus, making it relevant to Emergency Medicine practice and the examination.