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Digestive systems
- 1. Slide 2.1 Human AnatomyHuman Anatomy Digestive System pavemedicine.compavemedicine.com
- 2. Slide 14.15a Stomach AnatomyStomach Anatomy • “J” shaped flat bag • Located in epigastric, left hypochondriac regions • Food enters through gastroesophageal (cardiac) sphincter
- 3. Slide 14.17 Stomach AnatomyStomach Anatomy Figure 14.4a
- 4. Slide 14.15b Stomach AnatomyStomach Anatomy • Regions of the stomach • Cardiac region • Fundus • Body • Pylorus – terminal end • Food empties into the small intestine at the pyloric sphincter
- 5. Slide 14.16a Stomach AnatomyStomach Anatomy • Rugae – internal folds of the mucosa • External regions • Lesser curvature • Greater curvature
- 6. Slide 14.16b Stomach AnatomyStomach Anatomy • Layers of peritoneum attached to the stomach • Lesser omentum • Greater omentum • Contains fat to insulate, cushion, and protect abdominal organs
- 7. Slide 14.17 Stomach AnatomyStomach Anatomy Figure 14.4a
- 8. Slide 14.18 Stomach FunctionsStomach Functions • Acts as a storage site for food • Chemical digestion of protein begins • Delivers chyme (processed food) to the small intestine
- 9. Slide 14.19 Specialized Mucosa of the StomachSpecialized Mucosa of the Stomach • Simple columnar epithelium • Gastric glands – secrete gastric juice • Chief cells – produce pepsinogens • Parietal cells – produce hydrochloric acid • Endocrine cells – produce gastrin
- 10. Slide 14.20a Structure of the Stomach MucosaStructure of the Stomach Mucosa • Gastric pits • formed by folded mucosa • Glands and specialized cells • are deeper in the gastric gland region
- 11. Slide 14.20b Structure of the Stomach MucosaStructure of the Stomach Mucosa Figure 14.4b, c
- 12. Slide 14.21 Small IntestineSmall Intestine • Site of nutrient absorption • Muscular tube ~20’ long • extends from pyloric sphincter to ileocecal valve • Suspended from the posterior abdominal wall by mesentery
- 13. Slide 14.22 Subdivisions of the Small IntestineSubdivisions of the Small Intestine • Duodenum • Attached to the stomach • Curves around the head of the pancreas • Jejunum • Second portion, ~8’ • Ileum • Longest portion, ~10’
- 14. Slide 14.23a Chemical Digestion in the SmallChemical Digestion in the Small IntestineIntestine • Enzymes mix with chyme. Come from: • Intestinal cells • Pancreas (also adds HCO3 - ) • Bile enters from the gall bladder
- 15. Slide 14.23b Chemical Digestion in the SmallChemical Digestion in the Small IntestineIntestine Figure 14.6
- 16. Slide 14.24 Villi of the Small IntestineVilli of the Small Intestine • Fingerlike structures formed by the mucosa • Provide more surface area Figure 14.7a
- 17. Slide 14.26 Structures Involved in Absorption ofStructures Involved in Absorption of NutrientsNutrients • Absorptive cells • Blood capillaries • Lacteals (specialized lymphatic capillaries) Figure 14.7b
- 18. Slide 14.27 Folds of the Small IntestineFolds of the Small Intestine • Called circular folds or plicae circulares • Submucosal specialization • has Peyer’s patches • collections of lymphatic tissue
- 19. Slide 14.28 Large IntestineLarge Intestine • Larger in diameter, but shorter than the small intestine • ~6’ long • Has subdivisions • Named for direction of food movement
- 20. Slide 14.28 Large IntestineLarge Intestine Figure 14.8
- 21. Slide 14.29 Functions of the Large IntestineFunctions of the Large Intestine • Absorption of water • Eliminates indigestible food as feces • Does not participate in digestion • Goblet cells produce mucus for lubrication
- 22. Slide 14.29 Functions of the Large IntestineFunctions of the Large Intestine • Contains many bacteria (mostly E. coli) • Bacteria digest our wastes • Produce vitamins, amino acids • Vits. B, K • We absorb their “wastes”
- 23. Slide 14.30a Structures of the Large IntestineStructures of the Large Intestine • Cecum – saclike first part • Appendix • Accumulation of lymphatic tissue that may become inflamed (appendicitis) • Hangs from the cecum
- 24. Slide 14.30b Structures of the Large IntestineStructures of the Large Intestine • Colon • Ascending • Transverse • Descending • Sigmoid (S-shaped) • Rectum • Anus – external body opening
- 25. Slide 14.28 Large IntestineLarge Intestine Figure 14.8
- 26. Slide 14.31 Modifications to the LongitudinalModifications to the Longitudinal Layer of MuscleLayer of Muscle • Smooth muscle reduced to three bands (taeniae coli) • Muscle bands are shorter than colon • Walls are formed into pouches called haustra
- 27. Slide 14.32 Accessory Digestive OrgansAccessory Digestive Organs • Salivary glands • Teeth • Pancreas • Liver • Gall bladder
- 28. Slide 14.2b Organs of the Digestive SystemOrgans of the Digestive System Figure 14.1
- 29. Slide 14.33 Salivary GlandsSalivary Glands • Salivary glands: 3 pairs • Parotid glands – located anterior to ears • Submandibular glands • Sublingual glands
- 30. Slide 14.34 SalivaSaliva • Mixture of mucus and serous fluids • Helps to form food into a bolus • Contains salivary amylase • starch digestion • Dissolves chemicals for taste buds • We produce ~1 liter/day
- 31. Slide 14.35a TeethTeeth • Function to masticate (chew) food • Humans have two sets • Deciduous (baby or milk) teeth • 20 teeth are fully formed by age two
- 32. Slide 14.35b TeethTeeth • Permanent teeth • Replace deciduous teeth beginning ~6 years of age • A full adult set is 32 teeth • some people do not have wisdom teeth
- 33. Slide 14.36a Classification of TeethClassification of Teeth • Incisors (2) • Canines (1) • Premolars (2) • Molars (3) • Same number and type of teeth in each “quadrant” so…. • “Dental Formula”: 2-1-2-3
- 34. Slide 14.36b Classification of TeethClassification of Teeth Figure 14.9
- 35. Slide 14.39 LiverLiver • Largest gland in the body • Located in right hypochondriac region • Four lobes • Suspended by the falciform ligament • Connected to gall bladder via common hepatic duct
- 36. Slide 14.40 Primary Function of LiverPrimary Function of Liver • Produces bile for fat emulsification • Composition: water, plus… • Bile salts • Bile pigment (mostly bilirubin) • Cholesterol • Phospholipids • Electrolytes
- 37. Slide 14.77 Role of the Liver in MetabolismRole of the Liver in Metabolism • Final metabolism of most food • Detoxifies drugs and alcohol • Degrades hormones • Produces cholesterol, blood proteins • Regulates distribution of nutrients
- 38. Slide 14.41 Gall BladderGall Bladder • Sac attached to inferior surface of liver • Stores, concentrates bile • Bile enters duodenum in the presence of fatty food • Requires hormonal signals, autonomic innervation • Gallstones can cause blockages
- 39. Slide 14.38 PancreasPancreas • Exocrine function: Produces digestive enzymes • Enzymes: secreted into duodenum • Bicarbonate ions: neutralize acidic chyme • Endocrine products of pancreas • Insulin • Glucagon