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Functional Sphincters

Parotid salivary gland. Salivary glands :. Pharynx. Sublingual. Submaxillary. Esophagus. Stomach. Liver. Pancreas. Gallbladder. Duodenum. Transverse colon. Ascending colon. Descending colon. Cecum. Jejunum. Sigmoid. Appendix. Ileum. Rectum. Functional Sphincters . UES

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Functional Sphincters

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  1. Parotid salivary gland Salivaryglands: Pharynx Sublingual Submaxillary Esophagus Stomach Liver Pancreas Gallbladder Duodenum Transverse colon Ascending colon Descending colon Cecum Jejunum Sigmoid Appendix Ileum Rectum Functional Sphincters UES LES Pyloric Ileal IAS EAS

  2. To Systemic Circulation Rates: ml/min Aorta LIVER HEPATIC Celiac (700) (200) STOMACH SPLEEN Superior Mesenteric (700) (1800) mls/min Portal Vein PANCREAS SMALL INTESTINE Inferior Mesenteric (400) COLON

  3. Cross-Section of the Alimentary Canal Lymph node Villus Epithelium and Mucosa Muscularis mucosa Submucosa (contains most nerves and bloood vessels) Circular muscle Longitudinal muscle Serosa (connective tissue) Myenteric plexus Submucosal plexus Gland in submucosa

  4. Epithelial Cell Barrier • Microvilli: Brush Border • Glycocalyx: Digestive Surface • 1. Traps Nutrients • 2. Increases Local Viscosity • 3. Harbors Enzymes • Protective Barrier, Tight Junctions

  5. Neural Regulation of GI Function Autonomic Nervous System - INTRINSIC REGULATION: ENTERIC PLEXI - EXTRINSIC REGULATION: Central Nervous System

  6. Intrinsic Neural Regulation Myenteric ganglion Interganglionic fiber tract Circular muscle Submucosal ganglion Longitudinal Muscle 200 um Mucosa

  7. The Myenteric Plexus

  8. from CNS to CNS (+) (+) (-) Submucosal plexus S (-) Pressure receptor G S Mucosa H+ (+) Protein Signal Integration in the Plexi

  9. Autonomic Nervous System: Regulation of GI Function Extrinsic Regulation : Primarily Synapses onto Plexi CNS Autonomics Sympathetic (generally inhibits GI function); Norepi Parasympathetic (generally stimulated GI function) Vagus Nerve; Acetylcholine (Ach) Coordinates Functions through Long Reflexes Direct Innervation of Vascular Smooth Muscle by Sympathetic Nerves: Inhibits Blood Flow

  10. Parasympathetic division Sympathetic division Autonomic Nervous System Pancreas and Gall Bladder Vagal nuclei CNS Vagus nerves Preganglionic fibers Sympathetic ganglia Sacral Spinal cord Postganglionic fibers Pelvic nerves Enteric nervous system Submucosal plexus Myenteric plexus Blood vessels Smooth muscle Secretory cells Endocrine (G) cells

  11. Hormone: Classical Definition.A Chemical Messenger Produced and Secreted by a Specialized Gland, and Released into the Blood Where it is Circulated to Distant Organs to Elicit a Physiological Response.- Effects are Exerted Relatively Slowly, but for Prolonged Periods

  12. To Systemic Circulation Rates: ml/min Aorta LIVER HEPATIC Celiac (700) (200) STOMACH SPLEEN Superior Mesenteric (700) (1800) mls/min Portal Vein PANCREAS SMALL INTESTINE Inferior Mesenteric (400) COLON

  13. Local Stimuli Physiologic Circulating Name Composition for Release Action(s) Half-life TABLE 1. Characteristics of the Major Gastrointestinal Hormones Gastrin G17 peptide (2117 mw) peptides, amino acid secretion, 3 min G34 peptide (3988 mw) acids, distention Gastric growth 12 min Secretin peptide (3056 mw) duodenal acidity pancreatic 3 min bicarbonate secretion CCK-PZ peptide (3919 mw) fatty acids gallbladder contraction amino acids in pancreatic enzyme 5 min the sm. intestine secretion and growth (GIP) peptide (5105 mw) glucose, fatty insulin release 21 min Glucose- dependent acids in the small insulinotropic peptide intestine

  14. Secretin Family: Activates Adenylate Cyclase Secretin Increasing cAMP VIP GIP Glucagon Gastrin Family: Increases Intracellular Ca2+ Gastrin CCK Receptor Specificity

  15. Blood vessels Lymph vessels Nerves Smooth muscle Connective tissue lymphocytes Plasma cells Eosinophiles Absorp- tive cells Villous epithelium Goblet cells Crypt lumen Crypt Epithelium Undifferentiated Goblet Mitoses Endocrine cells Endocrine cells Paneth cells Muscularis mucosa

  16. Summary of Hormone Distributions

  17. [ Hormone] in Blood Length of Intestine stimulated

  18. Candidate Hormones Peptide Released by Actions From, F-cells of pancreatic islets Pancreatic polypeptide Intestinal Inhibits Pancreatic HCO3- Protein, Fat and Enzyme Secretion Glucose Motilin ? Distal Gastric Motility Intestinal Motility Enteroglucagon (GLP-1) Intestinal ? Fat, Sugar

  19. Neurocrines: NANC Neurotransmitters Peptide Site of Action Actions VIP Mucosa and Relaxes Muscle; Smooth Muscle Activates Cl- Channels GRP or Gastric Mucosa Stimulates Gastrin Bombesin Release Enkephalins Neurons in Mucosa Increases Smooth and Visceral Muscle Muscle Tone Substance P Salivary Glands Activates Blood Flow Neuropeptide Y Neurons in Mucosa Decreases Secretion and Visceral Muscle and Sphincter Tone CCK Enteric and Hypothalamic Inhibits Propulsion Neurons Activates Satiety NANC: Non-Adrenergic Non-Cholinergic

  20. Factor Location Actions Paracrine Somatostatin Stomach: Decreases Gastrin Pyloric Gland Secretion Histamine* Stomach and Increases Gastric Intestinal Mucosa Acid Secretion

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

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