ANATOMY AND PHYSIOLOGY OF The Digestive System UNIT 10.pptx

anatomy and physiology of digestive system

1. The Digestive System UNIT X 1

2. Objectives At the end of this session learner will be able to: Define the digestive system and list its functions Identify the various organs of digestive system Describe the anatomy & physiology of digestive organs Discuss the role of accessory organs in digestion Discuss digestion of food with in Mouth • Stomach • Small intestines • Large intestines Discuss the absorption of nutrients in the digestive system Discuss the process of defecation. 2

3. Digestive System 3

4. Digestive System Two groups of organs compose the Digestive System. Gastrointestinal tract or Alimentary Canal The Accessory Digestive System 4

5. Digestive System Gastrointestinal tract or alimentary The gastrointestinal tract or alimentary Canal is a continuous tube that extends from the mouth to the anus. Organs of the gastrointestinal tract include mouth, most of pharynx, esophagus, stomach, small intestine, large intestine. The length of the GI tract taken from cadaver is about 9m (30ft) 5

6. Digestive System The Accessory Digestive Organs Teeth Tongue Salivary glands Liver Gallbladder Pancreases 6

7. Accessory Digestive Organs 7

8. Accessory Digestive Organs 8

9. Accessory Digestive Organs 9

10. Accessory Digestive Organs 10

11. Digestive System Functions of Digestive System Ingestion Secretion Mixing and Propulsion Digestion Absorption Defecation 11

12. Digestive System Ingestion: this process involves taking food and liquids into the mouth (eating). Secretion: Each day, cells within the walls of the GI tract and accessory digestive organs secrete a total of about 7 liters of water, acid, buffers, and enzymes into the lumen (interior space) of the tract. 12

13. Digestive System 3. Mixing and Propulsion: Altering contractions and relaxation of smooth muscle in the walls of the GI tract mix food and secretions and propel them toward the anus. This capability of the GI tract to mix and material along its length is called Motility . 13

14. Digestive System Digestion: Mechanical and chemical process break down ingested food into small molecules. Mechanical Digestion Chemical Digestion 14

15. Digestive System Mechanical Digestion The teeth cut and grind food before it is swallowed, and then smooth muscles of the stomach and small intestine churn the food. As a result food molecules become dissolved and thoroughly mixed with digestive enzymes. 15

16. Digestive System Chemical Digestion The large carbohydrate, lipid, protein, and nuclei acid molecules in food are spilt into smaller molecules by hydrolysis. Digestive enzymes produced by the salivary glands, tongue stomach, pancreases, and small intestine catalyzed theses catabolic reactions. A few substance in food can be absorbed without chemical digestion these include vitamins and ions cholesterol and water. 16

17. Digestive System 5. Absorption: The entrance of ingested and secreted, fluid ion, and products of digestion into epithelial cells lining the lumen of the GI tract is called absorption. The absorption substance pass into blood or lymph and circulate to cells throughout the body. 17

18. Digestive System 6. Defecation: Wastes, indigestible substances, bacteria, cells, sloughed from the lining of the GI tract, and digested materials that were not absorbed in their journey through digestive materials leave the body through the anus the process called defecation. The elimination material is termed feces. 18

19. Layers of the GI Tract The wall of the GI tract from the lower esophagus to the anal canal has the same basic four layered arrangement of the tissues. The four layer of the tract, from deep to superficial are the mucosa, submucosa, muscularis, and serosa. 19

20. Layers of the GI Tract Mucosa: Inner lining of the GI tract is a mucous membrane. Its composed of (1) layer of epithelium in direct contact with the content of the GI tract, (2) layer of connective tissues called lamina propria , and (3) a thin layer of smooth muscle (muscularis mucosae). 20

21. Layers of the GI Tract Submucosa: The consist of areolar connective tissue that binds the mucosa to the muscularis. It contains many blood and lymphatic vessels that received absorbed food molecules. 21

22. Layers of the GI Tract Muscularis: The muscularis of the mouth, pharynx, and superior and middle parts of the esophagus contains skeletal muscle that produces voluntary swallowing. 22

23. Layers of the GI Tract Serosa: Those portion of the GI tract that are suspended in the abdominopelvic cavity have a superficial layers called the serosa. 23

24. Layers of the GI Tract 24

25. Layers of the GI Tract 25

26. Role of Accessory Organs in Digestion Teeth : Cut, tear, and Pulverize food Solid foods reduced to smaller particles for swallowing. Tongue: Move tongue from side to side and in and out. Food maneuvered for mastication shaped into, bolus, and maneuvered for swallowing. 26

27. Role of Accessory Organs in Digestion Cheeks and Lips: Keep food between teeth Salivary Glands: Secrete Saliva Lining of mouth and pharynx moistened and lubricated, Saliva Softens, moistens, and dissolves food and cleanses mouth and teeth salivary amylase splits starch into smaller fragments 27

28. Role of Accessory Organs in Digestion Pancreas Delivered pancreatic juice into the duodenum via the pancreatic duct. Liver Produces bile (bile salts) necessary for emulsification and absorption of lipids. 28

29. Role of Accessory Organs in Digestion Gall Bladder Stores, concentrates, and delivers bile into the duodenum via the common bile duct. 29

30. Mouth The mouth is refer to as the oral buccal cavity is formed by the checks, hard and soft palates and tongue . 30

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32. Stomach The stomach has four main regions: The cardia , surround the superior opening of the stomach. The rounded portion superior to and to the left of the cardia is the fundus, inferior to the fundus is the large central portion of the stomach called body. The regions of the stomach that connects to the duodenum is the pylorus. 32

33. Stomach Functions Mixes saliva food and gastric juice to from chyme. Serve as a reservoir for food before release into small intestine. Secretes gastric juice which contain HCL (kill bacteria and denature protein) Pepsin begin the digestion of protein intrinsic factor aids absorption of vitamin B12 and gastric lipase (Aids digestion of triglycerides). Secretes gastrin into blood. 33

34. Small intestines The small intestine is divided into three regions. The duodenum the shortest region is retroperitoneal. It starts at the pyloric sphincter of the stomach and extends about 25cm (10in) The jejunum is about 25cm 34

35. Small intestines Functions Segmentations mix chyme with digestive juices and bring food into contact with the mucosa for absorption peristalsis propels chyme through the small intestine. Completes the digestion of carbohydrates proteins, and lipids begins and completes the digestion of nucleic acids. Absorbs about 90% of nutrients water that pass through digestive system. 35

36. Large intestines The large intestine, which is about 1.5m(5ft). Long 6.5cm(2.5in) in diameter, extend from the ileum, to the anus. It is attached to the posterior abdominal, wall by its mesocolon, which is a double layer of peritoneum. Structurally the four major regions of the large intestine are the cecum, colon, return, and anal canal. 36

37. Large intestines Functions Haustral churning, peristalsis, and mass peristalsis drive the contents of the colon into rectum. Bacteria in the large intestine convert proteins to amino acids, breakdown amino acids, and produce some B vitamins and vitamin K. Absorbing some water ions, and vitamins. Forming feces Defecating (emptying the rectum) 37

38. Absorption of nutrients in the digestive system Passage of digested nutrient from the gastrointestinal tract into blood or lymph is called absorption. Absorption of material occurs via diffusion, facilitated diffusion and active transport. About 90% of all absorption of nutrients occur in small intestine. Other 10% occur in the stomach and large intestine. 38

39. Absorption of nutrients in the digestive system Absorption of Monosaccharides Absorption of Amino Acids Dipeptides and Tripeptides Absorption of lipids Absorption of Electrolytes Absorption of Vitamins Absorption of Water Absorption of Alcohol 39

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42. Reference Book 42

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44. Questions 44

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