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Understanding the Digestive System: Functions and Processes

The digestive system transforms complex organic nutrients into simpler forms, enabling absorption and utilization by the body. It consists of the alimentary tube (from mouth to anus) and accessory organs like the liver and pancreas. Digestion occurs through mechanical breakdown (chewing) and chemical processes involving enzymes. Key components include the mouth, esophagus, stomach, small intestine, large intestine, and associated organs. This intricate system ensures efficient nutrient absorption and plays a vital role in overall health.

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Understanding the Digestive System: Functions and Processes

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  1. DIGESTIVE SYSTEM

  2. FUNCTION • TO CHANGE COMPLEX ORGANIC NUTRIENT MOLECULES INTO SIMPLE ORGANIC AND INORGANIC MOLECULES

  3. DIVISIONS • ALIMENTARY TUBE – MOUTH TO ANUS • ACCESSORY ORGANS – OUTSIDE OF THE ALIMENTARY TUBE - TEETH, TONGUE, SALIVARY GLANDS, GALL BLADDER, PANCREAS, LIVER -CONTRIBUTES TO THE DIGESTIVE PROCESS BUT IT DOESN’T HAPPEN WITHIN THESE ORGANS

  4. TYPES OF DIGESTION • MECHANICAL – PHYSICAL BREAKDOWN OF FOOD INTO SMALLER PIECES • CHEMICAL – DIGESTIVE ENZYMES

  5. END PRODUCTS • CARBOHYDRATES – MONOSACCHARIDES EX. GLUCOSE, FRUCTOSE, GALACTOSE • PROTEINS – AMINO ACIDS • FATS – FATTY ACIDS AND GLYCEROL • RELEASE OF VITAMINS, MINERALS, AND WATER

  6. ORAL CAVITY • AKA BUCCAL CAVITY • TEETH ARE FOR MECHANICAL DIGESTION • 2 SETS - DECIDUOUS – 6 MO. TO 2 YR. (20 TEETH) - PERMANENT – START ABOUT 6 YEARS OLD (32 TEETH)

  7. LAYERS OF THE TOOTH • ENAMEL – OUTERMOST LAYER THAT IS RESISTANT TO DECAY, HARD SURFACE • DENTIN – SIMILAR TO BONE, FORMS THE ROOT OF THE TOOTH • PULP CAVITY – INNERMOST LAYER THAT CONTAINS BLOOD VESSELS AND NERVE ENDINGS

  8. TONGUE • TASTE BUDS AKA PAPILLAE ARE ON THE TOP • TASTE IS CN VII AND CN IX • TONGUE MANIPULATES FOOD • SWALLOWING IS INITIALLY AN VOLUNTARY ACTION BUT ONCE IT IS A BOLUS AND PAST THE UVULA, IT IS INVOLUNTARY • CN XII MOVES THE TONGUE

  9. SALIVARY GLANDS • PAROTID GLANDS • SUBMANDIBULAR GLANDS • SUBLINGUAL GLANDS • SALIVARY AMYLASE INITIATES CARBOHYDRATE BREAKDOWN IN THE MOUTH

  10. PHARYNX • NASOPHARYNX • OROPHARYNX • LARYNGOPHARYNX • FUNCTION IS SWALLOWING WHERE THE REFLEX IS INITIATED BY THE MEDULLA

  11. ESOPHAGUS • TAKES FOOD FROM THE PHARYNX TO THE STOMACH • PERISTALSIS FOR MOVEMENT OF THE FOOD • LES • GERD • NO ENZYMES • MUCOUS COATED

  12. STRUCTURAL LAYERS OF SYSTEM • 4 LAYERS • MUCOSA – INNER LAYER • SUBMUCOSA – CONTAINS MEISSNER’S PLEXUS THAT REGULATES SECRETIONS • EXTERNAL MUSCULAR LAYER – CONTAINS AUERBACH’S PLEXUS THAT ALLOWS CONTRACTIONS AND PERISTALSIS • SEROSA – OUTERMOST LAYER

  13. HOW LONG ARE YOUR INTESTINES? At least 25 feet in an adult. Be glad you're not a full-grown horse -- their coiled-up intestines are 89 feet long! • Chewing food takes from 5-30 seconds • Swallowing takes about 10 seconds • Food sloshing in the stomach can last 3-4 hours • It takes 3 hours for food to move through the intestine • Food drying up and hanging out in the large intestine can last 18 hours to 2 days! • Americans eat about 700 million pounds of peanut butter. • Americans eat over 2 billion pounds of chocolate a year. • In your lifetime, your digestive system may handle about 50 tons!!

  14. STOMACH • LOCATED IN THE LUQ IN FRONT OF SPLEEN • BOTH MECHANICAL AND CHEMICAL DIGESTION TAKES PLACE • MOST COMMON AREA FOR ULCER • SECRETES HCl THAT INITIATES PROTEIN BREAKDOWN AND KILLS BACTERIA • CHIEF CELLS SECRETE PEPSIN • MUCOUS CELLS SECRETE MUCOUS • CREATES CHYME • CHYME LEAVES STOMACH THROUGH PYLORIC SPHINCTER • pH

  15. GASTRIC ULCERS

  16. SMALL INTESTINE • BETWEEN THE STOMACH AND THE CECUM • ALKALINE • ABOUT 20 FEET LONG 3 PARTS • DUODENUM – 10 INCHES LONG. SECOND MOST COMMON AREA OF ULCERS - pH • JEJUNUM – ABOUT 8 FT. LONG • ILEUM – ABOUT 11 FT. LONG • DIGESTION AND ASSIMILATION OCCURS HERE

  17. ABSORPTION OF NUTRIENTS • PLICA CIRCULARIS – CIRCULAR FOLDS • VILLI • MICROVILLI • THESE INCREASE SURFACE AREA • DIFFUSION, ACTIVE TRANSPORT, OSMOSIS

  18. INCREASES SURFACE AREA

  19. LARGE INTESTINE • ABOUT 5 FT. LONG BUT 2.5 INCHES IN DIAMETER • PARTS INCLUDE: -CECUM -ASCENDING COLON -TRANSVERSE COLON -DESCENDING COLON -SIGMOID COLON - RECTUM -ANUS

  20. ILEOCECAL VALVE – BETWEEN ILEUM AND CECUM AND PREVENTS THE BACKFLOW OF FECAL MATERIAL • APPENDIX IS ATTACHED TO THE CECUM • NO DIGESTION OCCURS HERE • MUCOUS FOR LUBRICATION • HAUSTRA INCREASES SURFACE AREA • ABSORPTION OF WATER, MINERALS, AND VITAMINS • VITAMINS PRODUCED BY NORMAL FLORA

  21. ELIMINATION • ACCOMPLISHED BY THE DEFECATION REFLEX WHICH MAY BE CONTROLLED VOLUNTARILY • INTERNAL SPHINCTER (INVOLUNTARY) • EXTERNAL SPHINCTER (VOLUNTARY)

  22. ENZYMES • FUNCTION WITHIN THE SMALL INTESTINE • COME FROM THE LIVER, PANCREAS, SMALL INTESTINE

  23. LIVER • FORMS BILE • BILE EMULSIFIES (MECHANICAL DIGESTION) • BILE IS MADE BY THE LIVER

  24. GALL BLADDER • STORES BILE • CCK STIMULATES THE CONTRACTION OF THE GALL BLADDER TO RELEASE BILE AND SEND IT TO THE DUODENUM

  25. PANCREAS • RELEASES ENZYMES TO BREAK DOWN ALL MACRONUTRIENTS • AMYLASE – FOR CARBOHYDRATE BREAKDOWN • LIPASE – FOR FAT BREAKDOWN • TRYPSIN – FOR PROTEIN BREAKDOWN

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