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  1. ANNOUNCEMENTS SECOND EXAM: Wednesday, April 22nd Material Covered: Bone, Muscle, Nerve & Circulatory, Lymphatic, & Urinary Systems REVIEW SESSION TODAY, 4/21 6-7PM ISB 364 LAB PRACTICAL RESCHEDULED: April 28, 29 Material Covered: Urinary, Exocrine, & Endocrine Systems, Digestive System & Accessory Organs, and Lymphatic System and Reproductive Systems. Final Exam: May 18th 1:30 PM in Morrill 203

  2. LAB SCHEDULE Week of April 20: Work in lab group to, choose organs, complete frozen sections, design immunohistochem. Experiment. Week of April 27: Lab Practical and learn to section embedded material. Week of May 4: Immunohistochemistry. Complete sectioning & staining of embedded material. In class, May 11: Share results, discuss interpretation. May 18: Lab Project report due at Final Exam.

  3. *BIOLOGY SENIORS* Join us for lunch! 12 Noon Wednesday, May 13th Lawn, Durfee Conservatory

  4. Anatomy of the Stomach 3 regions: Cardiac Pyloric Fundic Rugae: longitudinal folds or ridges on inner surface

  5. Each stomach region • has distinctive glands. • Cardiac glands • Pyloric glands • Fundic glands • -gastric pits • -isthmus • cell replication • -neck • -base or fundus

  6. Anatomy of the Small Intestine 3 components: Duodenum, Jeunum, Ileum - Plicae circularis - Villi - Microvilli - Simple columnar epithelium

  7. Anatomy of the Small Intestine

  8. Secretion / Digestion / Absorption epithelial cells and associated glands salivary glands pancreas gall bladder stomach small & large intestine Secretions include: antibodies: IgA lubricants hydrochloric acid digestive enzymes hormones water

  9. Secretion / Digestion / Absorption - initiated in mouth - stomach lumen - completed in small intestinal lumen - aided by HCl from stomach - amylase from saliva & stomach - pancreatic enzymes - enzymes in glycocalyx of small intestine - aided by bile from gall bladder

  10. Secretion / Digestion / Absorption across epithelium of small intestine and large intestine 10.

  11. Lubrication: Mucous Secretions Esophagus- Lubrication and protection from regurgitation of acidic stomach contents Stomach- surface mucous cells; mucous protects from abrasion, contains bicarbonate; protects mucosa from acidic stomach contents (chyme) Small Intestine- goblet cells, # increases from duodenum=> ileum Large Intestine- goblet cells, # increases toward rectum

  12. Mouth Stomach Small Large IntestineIntestine Carbohydrate Protein Lipids Nuclei Acids Digestive Secretions Digestive Secretions from Pancreas Absorption Bile from gall bladder

  13. Specialized Cells for Stomach Secretion Surface Mucous Cells: gastic pit and neck of gastric gland PAS stain for carbohydrates

  14. Specialized Cells for Stomach Secretion Parietal (Oxyntic) Cells: - neck & deep parts of fundic glands - release HCl and intrinsic factor (B12 absorption) - large - triangular - acidophilic

  15. Parietal (Oxyntic) Cells Anti-parietal cell antibody

  16. Parietal (Oxyntic) Cells HCl Synthesis: H+ and Cl- ions pumped into intracellular canalicular system, HCl formed

  17. Specialized Cells for Stomach Secretion Chief Cells: deep in fundic glands, protein-secreting, lots of RER, basophilic, zymogen granules Secrete pepsinogen HCl Pepsinogen---------> Pepsin

  18. Specialized Cells for STOMACH Secretion Enteroendocrine cells: small - more common in gland base - pale, vesicles don’t fix well - may not reach lumen, but sample lumenal contents with microvilli -release variety of hormones into blood

  19. Enteroendocrine cells

  20. Small Intestine Increased Surface Area: Plicae circularis, Villus, Intestinal Gland (Crypts of Lieberkuhn) Villus: Capillary Lacteal (lymphatic capillary) Smooth muscle

  21. Plicae circularis: transverse folds with core of mucosa

  22. Small Intestine: Villi and Crypts of Lieberkuhn

  23. Specialized Cells of the Small Intestine Enterocytes (intestinal absorptive cells) Paneth cells- secrete antimicrobial substances Enteroendocrine cells- release hormones M cells- dome cells cap lymphatic nodules Goblet cells- mucous secreting

  24. Enterocytes (intestinal absorptive cells) Tall columnar cells Microvilli=>striated border Epithelial specializations -Terminal web - Tight junctions Secrete Digestive Enzymes

  25. Paneth Cells • - base of intestinal glands • large • intense acidophilic granules • phagocytose bacteria • secrete lysozyme- digests • bacterial cell wall

  26. Epithelial Renewal in Stomach and Small Intestine

  27. Large Intestine Simple columnar epithelium Absorption of water and electrolytes Columnar absorptive cells Crypts of Lieberkuhn Goblet cells

  28. Secretion / Digestion / Absorption • Requires coordination of secretion and motility with ingestion • NERVOUS AND HORMONAL SIGNALS

  29. Secretion / Digestion / Absorption • Requires coordination of secretion with ingestion • NERVOUS AND HORMONAL SIGNALS • Release of saliva • Release of digestive enzymes • Release of HCl • Release of bile from gall bladder • Motility of gastrointestinal tract

  30. Secretion / Digestion / Absorption What signals might trigger release of hormones and digestive enzymes?

  31. Gastrin secretion: release from stomach enteroendocrine cells (G cells) is stimulated by 1) peptides and amino acids in stomach lumen 2) distention of stomach wall 3) sensory inputs --> neural innervation (GRP) - Parietal cells have gastrin receptors GASTRIN RELEASE HCl RELEASE PEPSIN ACTIVATION PROTEIN DIGESTION

  32. Regulation Parietal CellHCl secretion HCl produced by parietal cell Gastrin produced by G cell

  33. Choleocystokinin (CCK): hormone released from enteroendocrine cells of small intestine is stimulated by presence of H+, amino acids, and fatty acids - Pancreatic cells have CCK receptors**(may act through neurons innervating the pancreas in humans) CCK RELEASE (INTESTINAL ENDOENDOCRINE CELLS) PANCREATIC DIGESTIVE ENZYME RELEASE DIGESTION OF CARBOHYDRATES, PROTEINS, LIPIDS IN SMALL INTESTINE


  35. PANCREAS: Endocrine / Exocrine Gland

  36. PANCREAS: Exocrine Gland

  37. PANCREAS: Exocrine Gland

  38. PANCREAS Islet of Langerhans



  41. GALL BLADDER - lumen lined by simple columnar epithelium - microvilli, tight junctions, mitochondria - smooth muscle - concentrates bile (Na+ actively pumped out of lumen in exchange for H+, water follows) - stores bile until release