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Buccinator

Buccal Cavity: Primary Salivary Glands. Stensen’s duct. Buccinator. Masseter muscle. Parotid gland. Sublingual gland. Mandible. Wharton’s duct. Submaxillary Gland. Organization of the “Salivon”. Acinar cells. Ductal cells. Myoepithelial cell.

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Buccinator

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  1. Buccal Cavity: Primary Salivary Glands Stensen’s duct Buccinator Masseter muscle Parotid gland Sublingual gland Mandible Wharton’s duct Submaxillary Gland

  2. Organization of the “Salivon” Acinar cells Ductal cells Myoepithelial cell Filtration: In the Acinus is Primarily Passive Acinus Intercalated duct Striated duct Myoepithelial cell

  3. Functions of Saliva: Digestion, Protection-Lubrication Digestive: a-Amylase: Starch Digestion pH optima 7.0; Active in Proximal Stomach Ligual Lipase: Fat Digestion pH optima ~4.0; does not require bile salts Lubrication/Protection: Anti-Bacterial: I -, SCN -, Secretory IgA, Lysozyme and Lactoferrin Anti-Corrosive: HCO3 to buffer pH; F- Ca2+. Lubrication: Mucus- Mucopolysaccharides, H2O Coat the Food to Aid in Swallowing-Taste Prevent Abrasion

  4. Acinar cells Ductal cells Myoepithelial cell Acinus Intercalated duct Striated duct Myoepithelial cell Organization of the “Salivon” SP Filtration: In the Acinus is Primarily Passive Acetylcholine Capillaries SP: Substance P

  5. Stomach Anatomy

  6. Gastric Pits and Glands Gastric Lumen Gastric Pits Columnar Epithelium Mucosa Lamina Propria Gastric Gland Sub-Mucosa Lymph Node Lymphatics Mucularis Serosa

  7. GASTRIC GLANDS Gastric Lumen Mucus Gastric Pits Superficial epithelial cells Mucus neck cells Parietal cells (Oxyntic) Peptic cells

  8. The Epithelial Protective Barrier Tight Junctions between Adjacent Cells Mucus and Bicarbonate Secretion Rapid Turnover – Cell Migration and Proliferation : All Appear to be Driven by Prostaglandins

  9. Oxyntic Gland Secretions Cell Type Component Function: (P/D) • Peptic Gastroferrin Iron Binding Protein P • Pepsin-ogen Protease D • Mucus Neck Mucopolysaccharides; HCO3 P • Oxyntic Intrinsic Factor B12 Binding D Protein • HCl Digestion/ P/D “denaturation” P- Protective; D- Digestive

  10. Roles of HCl in the Stomach Protein Digestion : Activates Pepsin Denatures and Solubilizes Tissue Protective: Kills Bacteria

  11. CA – Carbonic Anhydrase Lumen of gland Baso-Lateral CA The Oxyntic Cell H2CO3 CO2 Metabolism HCO3- HCO3- H+ H+ Cl- ATP Canaliculus K+ K+ Cl- Cl- Cl- Na+ ATP K+ Na+

  12. Role of Carbonic Anhydrase CO2 + H2O H2CO3 HCO3- + H+ CA

  13. Key Players: HCl Secretion Location Inhibitor • H+ / K+ ATPase : Lumenal Omeprazole • Carbonic Cytosolic Acetozolamide Anhydrase • Na/K ATPase Basolateral Ouabain • K+ / Cl- cotransport : Lumenal Cl- / HCO3 antiport: Basolateral

  14. Histamine Acetylcholine A CM Gastrin CM A A CM Ca2+ Adenylate IP3 ATP cAMP Cyclase Ca2+ La2+ Ca2+ A - ATROPINE Ln2+- Lanthanum CM - Cimetidine Blocks Does not block H+ H+ Secretion

  15. Phases of Secretion Phase Stimuli Pathway • Cephalic Smell, Taste Central reflexes • Gastric Chyme Enters Stomach Distension, Local Effects Amino Acids • Intestinal Chyme Enters Local Feedback the Intestine • Inter-Digestive Histamine Basal Release

  16. Primary Mechanisms for Inhibiting HCl Secretion Location (Phase) Stimuli Pathway • Antrum Acidification pH < 3 Somatostatin Inhibition (Gastric) Maximal pH < 1 of Gastrin Secretion • Duodenum Distension Enteric (Local) Reflexes (Intestinal) pH < 6 Fat and Peptides Entero-gastrone?

  17. Regulation of G-Cell Secretion Vagus nerves Ach Ach Myenteric Plexus + Ach GRP Somato- statin Cell Gastrin Cell Gastrin Digested Protein H+

  18. Body ECL Antrum

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