The document summarizes the process of digestion from ingestion to movement through the gastrointestinal tract. It describes: 1) Mastication and swallowing, which begins the voluntary stage and transitions to involuntary movements. 2) Coordination of the pharyngeal and esophageal stages by the brain stem to safely transport food to the stomach through contractions. 3) The stomach's motor functions of storage, mixing, and emptying food into the small intestine through peristaltic waves and regulation by gastric and duodenal factors. 4) Movements in the small intestine including mixing and propulsive movements to gradually move food and aid digestion over several hours.

1. Gastrointestinal physiology Transport & mixing of food in the GIT: Dr.M.A.M.Shaikhani.

7. The Swallowing Process

10. 1.Pharyngeal stage: C. Strong approximation of laryngeal vocal cords with the backward swinging of epiglottis(due to the presence of a ligament which prevent its upward movement ),blocks the opening of larynx preventing passage of food bolus into the trachea & so preventing suffocation .The vocal cords & larynx are more important than epiglottis as laryngeal or vocal paralysis causes strangulation while removal of epiglottis usually dose not cause serious disability in swallowing. D. Upper 3-4 cms. Of esophagus forms the pharyngeo-esophageal sphincter(remains tonicly contracted between swallowings to prevents air swallowing into esophagus & stomach during respiration), become relaxed during this stage by the upward movement of larynx& also the entire pharynx contracts allowing easy movement of food from posterior pharynx into the upper esophagus.

19. Esophagus Fundus Body Antrum Pyloric Sphincter Duodenum

24. Mechanical Processes: Mixing and Emptying Pyloric Sphincter (open) Duodenum Fundus Body Antrum 3. A small amount of chyme is pushed into the duodenum. 2. Most mixing occurs in the antrum. Chyme Food Peristaltic Waves 1. Peristaltic Waves begin in the fundus.

25. Mechanical Processes: Mixing and Emptying Duodenum 4. When the peristaltic wave reaches the pyloric sphincter it closes. Pyloric Sphincter (closed) Chyme

26. Mechanical Processes: Mixing and Emptying Duodenum 4. When the peristaltic wave reaches the pyloric sphincter it closes. Pyloric Sphincter (closed) 5. The remainder of the chyme is propelled backwards. Chyme 6. The next wave of peristalsis pushes the chyme forward again.

27. Duodenum Pyloric Sphincter (closed) Factors in the Duodenum that Influence the Rate of Gastric Emptying 1. Fat 3. Hypertonicity 2. Acid 4. Distention Chyme