Structure and Function of the Digestive System Chapter

Structure and Function of the Digestive System Chapter 33 Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Gastrointestinal Tract Mouth Esophagus Stomach Small intestine Large intestine Rectum Anus Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Gastrointestinal Tract Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Gastrointestinal Tract Ingestion of food Propulsion of food and wastes from the mouth to the anus Secretion of mucus, water, and enzymes Mechanical digestion of food particles Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Gastrointestinal Tract Chemical digestion of food particles Absorption of digested food Elimination of waste products by defecation Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Gastrointestinal Tract Histology Ø Mucosa Ø Submucosa Ø Muscularis Ø Serosa or adventitia Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Gastrointestinal Tract Enteric plexus Submucosal plexus Myenteric plexus Submucosa(glands & ducts) Mucosa Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Gastrointestinal Tract Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Mouth Reservoir for chewing and mixing of food with saliva Taste buds Ø Salty, sour, bitter, sweet, and umami Olfactory nerves( CN I ) Teeth Ø 32 permanent teeth Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Salivary Glands Three pairs Ø Submandibular Ø Sublingual Ø Parotid Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

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Salivary Glands Saliva Ø Water with mucus, sodium, bicarbonate, chloride, potassium, and salivary alphaamylase (carbohydrate digestion) Ø Controlled by sympathetic and parasympathetic fibers Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

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Swallowing Esophagus Peristalsis Ø Primary and secondary Upper esophageal sphincter Lower esophageal sphincter Phases Ø Oral and pharyngeal phases Ø Esophageal phase Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Stomach The stomach is a hollow, muscular organ that stores food, secretes digestive juices, mixes food with the juices, and propels partially digested food (chyme) Muscle layers Ø Longitudinal Ø Circular Ø Oblique Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Stomach Boundaries Ø Cardiac orifice Ø Pyloric sphincter Ø Pylorus Functional areas Ø Fundus Ø Body Ø Antrum Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Stomach Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Stomach Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Gastric Motility Swallowing Gastrin Cholecystokinin Motilin Secretin Gastric emptying Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Gastric Secretion The stomach secretes large volumes of gastric juices Ø Mucus Ø Acid Ø Enzymes Ø Hormones Ø Intrinsic factor Ø Gastroferrin Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Gastric Secretion Gastric glands Ø Parietal cells • Hydrochloric acid and intrinsic factor Ø Chief cells • Pepsinogen Ø G cells • Gastrin Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Gastric Secretion Gastric glands Ø Enterochromaffin-like cells • Histamine Ø D cells • Somatostatin Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Vagus Nerve Vagus nerve (X) gastrin histamine H 2 receptors parietal cells HCL Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Stomach Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Gastric Pits and Gastric Glands Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

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Gastric Secretion Phases of gastric secretion: acid secretion Ø Cephalic phase Ø Gastric phase Ø Intestinal phase Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Small Intestine 5 to 6 meters long Three segments Ø Duodenum Ø Jejunum Ø Ileum • Ileocecal valve Peritoneum Ø Peritoneal cavity Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Small Intestine Muscle layers Ø Outer—longitudinal Ø Inner—circular Myenteric plexus Mucosal folds (plica) Villi Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Small Intestine Microvilli ØBrush border Lamina propria Lacteal Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Small Intestine Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Villi: ”absorptive fingers” Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Intestinal Digestion and Absorption Hydrochloric acid Pepsin Pancreatic enzymes Intestinal enzymes Bile salts Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Intestinal Digestion and Absorption Major nutrients Ø Carbohydrates Ø Proteins Ø Fats Ø Water Ø Electrolytes Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Intestinal Digestion and Absorption Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Gastrointestinal Absorption Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Intestinal Motility The movements of the small intestine facilitate both digestion and absorption Haustral segmentation Peristalsis Ileogastric reflex Intestinointestinal reflex Gastroileal reflex Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Large Intestine Cecum Appendix Colon Ø Ascending Ø Transverse Ø Descending Ø Sigmoid Rectum Anus Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Large Intestine Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Large Intestine Ileocecal valve O’Beirne sphincter Internal anal sphincter External anal sphincter Taenia coli Haustra Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Large Intestine Defecation stimulated by: ØGastrocolic reflex ØDefecation reflex Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Intestinal Bacteria The environment of the stomach is relatively sterile because of secreted stomach acid Bile acid secretion, motility, and antibody production keeps bacterial numbers in the duodenum to a minimum Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Intestinal Bacteria There is a low concentration of aerobes in the jejunum Anaerobic bacteria are distal to the ileocecal valve Ø Anaerobes are 95% of the fecal flora in the colon Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Splanchnic Blood Flow Provides blood flow to the esophagus, stomach, small and large intestine, liver, gallbladder, pancreas, and spleen Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Splanchnic Circulation Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Accessory Organs of Digestion Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

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Accessory Organs of Digestion Liver Ø Lobes • Separated and attached to the anterior abdominal wall by the falciform ligament • Right lobe Caudate and quadrate lobes • Left lobe Ø Glisson capsule Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Liver Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Hepatic Portal Circulation Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Liver lobules Ø Hepatocytes Ø Sinusoids Ø Bile canaliculi Ø Common bile duct Ø Major duodenal papilla (sphincter of Oddi) Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Liver Lobules Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Liver Kupffer cells Stellate cells Pit cells Disse space Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Secretion of Bile is an alkaline, bitter-tasting yellowish green fluid that contains bile salts, cholesterol, bilirubin, electrolytes, and water Bile is formed by hepatocytes and secreted into the bile canaliculi Enterohepatic circulation Ø Recycling of bile salts Ø Primary and secondary bile acids Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Enterohepatic Circulation Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Metabolism of Bilirubin is a by-product of the destruction of aged red blood cells Bilirubin gives bile a greenish black color and produces the yellow tinge of jaundice Unconjugated bilirubin Conjugated bilirubin Urobilinogen Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Metabolism of Bilirubin Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Vascular and Hematologic Liver Functions-9 1. Blood storage 2. Bacterial and foreign particle removal 3. Synthesizes clotting factors 4. Produces bile to absorb fatsoluble vitamins 5. Metabolizes fats Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Vascular and Hematologic Liver Functions 6. Metabolizes proteins 7. Metabolizes carbohydrates 8. Metabolic detoxification 9. Storage of minerals and vitamins Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Gallbladder The gallbladder is a saclike organ that lies on the inferior surface of the liver The function of the gallbladder is to store and concentrate bile between meals The gallbladder holds about 90 m. L of bile Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Exocrine Pancreas The exocrine pancreas is composed of acini and networks of ducts that secrete enzymes and alkaline fluids to assist in digestion Pancreatic duct (Wirsung duct) Ampulla of Vater Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Exocrine Pancreas Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Exocrine Pancreas Secretions Ø Potassium, sodium, bicarbonate, magnesium, calcium, and chloride Enzymes Ø Trypsinogen, chymotrypsinogen, and procarboxypeptidase Ø Trypsin inhibitor Ø Pancreatic alpha-amylase Ø Pancreatic lipase Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Aging and the Digestive Function Tooth enamel and dentin wear down Teeth are lost Periodontal disease Gum recession Osteoporotic bone changes Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Aging and the Digestive Function Number of taste buds decline Sense of smell diminishes Salivary secretion decreases Decreased esophageal and gastric motility Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.