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Digestive System.

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Presentation on theme: "Digestive System."— Presentation transcript:

1 Digestive System

2 introduction

3 Overview Gastrointestinal Tract (GI Tract) – from mouth to anus
Accessory organs – teeth, tongue, salivary glands, liver, gallbladder, pancrea s

4 Functions Ingestion Secretion – H20, enzymes, acid, buffers
Mixing and propulsion – peristalsis Digestion – mechanical and chemical breakdown Absorption Defecation

5 structures

6 Mouth, Pharynx & Esophagus
Mouth includes teeth, tongue, salivary glands Pharynx – throat; swallowing reflex Esophagus – muscular tube; transports food to the stomach; some absorption

7 Stomach J-shaped enlargement of the GI tract Gastric Juice:
Mucus Pepsinogen HCl Intrinsic factor Chyme: thick liquid of gastric juice and food


9 Stomach 4 Layers of stomach wall Mucosa Secretory Cells
Rugae – folds of stomach wall Columnar epithelium – secretes mucus Secretory Cells Mucus cells Parietal Cells – HCl and Intrinsic factor (vit. B12 absorption) Chief cells – secrete pepsinogen G cells – secrete gastrin

10 Stomach Muscularis 3 layers of muscle Serous Membrane
Forms the greater omentum and mesentery


12 Small Intestine 3 sections: duodenum, jejunum, ileum
Most of digestion and absorption takes place here Absorptive cells in the microvilli Absorption of sugars, amino acids, H2O, lipids, vitamins Digestive enzymes come from pancreas and small intestine

13 Small Intestine Digestive enzymes: Maltase, sucrase, lactase Lipase
Absorption: Simple sugars, amino acids, ions, H2O, lipids, and vitamins


15 Large Intestine 1st section at opening of ileum – cecum; appendix attached 4 regions: ascending, transverse, descending, and sigmoid colon Final stage of digestion (work of bacteria) Absorption of H2O, vitamins Chyme → feces → defecation (elimination)


17 Pancreas Pancreatic juice: H2O, salts, HCO3-, enzymes Enzymes:
Amylase; breaks down starches Trypsin; breaks down proteins (inactive form) Lipase; breaks down fats


19 Liver & Gallbladder Bile: emulsifies large lipid globules; stored in gallbladder Functions: Carbohydrate metabolism – blood glucose levels Lipid metabolism – cholesterol production, etc. Protein metabolism – ATP production, converting ammonia into urea, plasma protein production

20 Liver & Gallbladder Functions (continued)
Processes drugs and hormones; detox center Stores minerals and vitamins Activates vitamin D


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