Gastrointestinal System.pptx

bowel dysfunction

1. Gastro- Intestinal System

2. introduction The gastrointestinal tract (GI tract, GIT, digestive tract, digestion tract, alimentary canal) is the tract from the mouth to the anus which includes all the organs of the digestive system in humans and other animals. Food taken in through the mouth is digested to extract nutrients and absorb energy, and the waste expelled as feces.

3. Functions Ingestion Secretion Mixing and propulsion Digestion Absorption Defecation

4. structure Upper gastro intestinal tract Mouth Pharynx Oesophagus Stomach Duodenum and the salivary glands, liver, pancreas and gall bladder have important functions in the digestive system. Lower gastro intestinal tract Small intestine Large intestine

5. Functions

6. Summary of organs of the digestive system and their functions ORGANS FUNCTIONS Tongue Helps food for mastication, shapes food into a bolus, manuevers food for deglutition, detects sensations for taste, and initiates digestion of triglycerides. Salivary glands Saliva produced by these glands softens, moistens, and dissolves foods; cleanses mouth and teeth; initiates the digestion of starch Teeth Cut, tear and pulverize food to reduce solids to smaller particles for swallowing. Pancreas Pancreatic juice buffers acidic gastric juice in chyme, stops the action of pepsin from the stomach, creates the proper pH for digestion of Carbohydrate, proteins, triglycerides and nuclei acids Liver Produce bile, which is required for the emulsification and absorption of lipids in the small intestine Gall bladder Stores and concentrates bile and releases it into the small intestine

7. ORGANS FUNCTIONS Mouth The cheeks and lips keep food between the teeth during mastication, and buccal gland lining the mouth produce saliva Pharynx Receives a bolus from the oral cavity and passes it into the esophagus Esophagus Receives the bolus from pharynx and moves it into the stomach; this requires relaxation of the upper esophagus sphincter and secretion of mucus Stomach Mixing waves combine saliva, food and gastric juice which activates pepsin, initiates protein digestion, kills microbes in food, helps absorb vitamin B 12 , contracts the lower esophageal sphincter, increases stomach motility, relaxes the pyloric sphincter, and moves chyme into small intestine Small intestine Segmentation mixes chyme with digestive juices, peristalsis propels chyme towards the ileocecal sphincter; digestive secretions from the small intestine, pancreas and liver complete the digestion of carbohydrates, proteins, lipids and nuclei acids, circular folds, villi, and microvilli help absorb about 90 percent of digested nutrients Large intestine Haustral churning, peristalsis and mass peristalsis drive the colonic contents into the rectum, bacteria produce some B vitamins and vitamin K; absorption of some water, ions and vitamins occue , defecation

8. defecation Defecation is an episodic event for the elimination of the feces It is controlled by the neurological reflex and sphincter which ordinarily occurs only in appropriate circumstances and times

9. Small intestine

10. Large intestine

11. Defecation reflex

12. Thank you