Human Anatomy, 3rd edition The Digestive System Chapter 25 Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition Introduction Structure of the digestive system A tube that extends from mouth to anus Accessory organs are attached Functions include Ingestion Movement Digestion Absorption Defecation Human Anatomy, 3rd edition Prentice Hall, © 2001

Overview of Digestive System FG25_01.JPG Title: Components of the Digestive System Notes: This figure introduces the accessory organs and major regions of the digestive tract, together with their primary functions. Keywords: digestive system, components, oral cavity, teeth, tongue, liver, gallbladder, large intestine, salivary glands, pharynx, esophagus, stomach, pancreas, small intestine Human Anatomy, 3rd edition Prentice Hall, © 2001

Histological Organization The wall of the digestive tract has the same basic arrangement of tissues from the esophagus to the anal canal Four layers (from innermost to outermost) Mucosa Submucosa Muscularis Serosa Human Anatomy, 3rd edition Prentice Hall, © 2001

Layers of the Digestive Tract FG25_02A1.JPG Title: Histological Structure of the Digestive Tract Notes: (a) Three-dimensional view of the histological organization of the digestive tube. (b)Photomicrograph of ileum; histological organization. Keywords: digestive tract, histology, mesentery, plica, mucosa, submucosa, muscularis externa, visceral peritoneum, serosa, villi, mucosal glands, lymphatic vessel, muscularis mucosae, myenteric plexus, longitudinal muscle layer, circular muscle Human Anatomy, 3rd edition Prentice Hall, © 2001

Layers of the Digestive Tract FG25_02A2.JPG Title: Histological Structure of the Digestive Tract Notes: (a) Three-dimensional view of the histological organization of the digestive tube. (b)Photomicrograph of ileum; histological organization. Keywords: digestive tract, histology, mesentery, plica, mucosa, submucosa, muscularis externa, visceral peritoneum, serosa, villi, mucosal glands, lymphatic vessel, muscularis mucosae, myenteric plexus, longitudinal muscle layer, circular muscle Human Anatomy, 3rd edition Prentice Hall, © 2001

Movement & Mixing of Digestive Materials Peristalsis Coordinated motion of the two muscular layers Circular muscles contract, then longitudinal muscles Segmentation Mixing of food Circular muscles in two areas contract Longitudinal muscles alternately contract & relax Human Anatomy, 3rd edition Prentice Hall, © 2001

Peristalsis & Segmentation FG25_03.JPG Title: Peristalsis and Segmentation Notes: (a)Peristalsis propels materials along the length of the digestive tract by coordinated contractions of the circular and longitudinal layers. (b)Segmentation movements involve circular layers; mix and churn, but no directional movement. Keywords: peristalsis, contractions, circular, longitudinal, bolus, segmentation, churn Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition The Oral Cavity Functions Take in food Prepare food for digestion Structure Lined with stratified squamous epithelium Lips surround the opening Roof is formed from the hard & soft palate Tongue dominates the floor Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition Oral Cavity FG25_05A.JPG Title: The Oral Cavity Notes: (a) The oral cavity as seen in sagittal section. (b) An anterior view of the oral cavity, as seen through the open mouth. Keywords: oral cavity, sagittal, epiglottis, tonsil, nasopharynx, oropharynx, soft palate, tongue, hard palate, lingual frenulum, submandibular ducts, palatoglossal arch, uvula Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition Oral Cavity FG25_05B.JPG Title: The Oral Cavity Notes: (a) The oral cavity as seen in sagittal section. (b) An anterior view of the oral cavity, as seen through the open mouth. Keywords: oral cavity, sagittal, epiglottis, tonsil, nasopharynx, oropharynx, soft palate, tongue, hard palate, lingual frenulum, submandibular ducts, palatoglossal arch, uvula Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition The Tongue Functions Maneuvers food Structure Skeletal muscle covered with mucosa The lingual frenulum connects the tongue to the floor of the mouth Surface Papillae Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition The Salivary Glands Found outside the mouth Ducts carry saliva to the mouth Saliva Functions Keeps mucous membranes moist Lubricates food Dissolves food Begins carbohydrate digestion 3 pairs Parotid glands Submandibular glands Sublingual glands Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition Salivary Glands FG25_06A.JPG Title: The Salivary Glands Notes: (a) Lateral view, showing the relative positions of the salivary glands and ducts on the left side of the head. (b)Photomicrograph showing histological detail of parotid, submandibular, and sublingual salivary glands. Keywords: salivary glands, ducts, lingual frenulum, sublingual duct, sublingual salivary, submandibular, parotid, serous cells, mucous cells, enzymes, mucins Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition Teeth 2 sets Deciduous (20) Permanent (32) Held in sockets Gingiva surrounds the base of the teeth Structure Crown Root Neck Composition Dentin – primary substance in tooth Enamel – covers crown Cementum – covers root Tooth decay Wisdom teeth – 3rd molars Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition A Tooth FG25_07A.JPG Title: Teeth Notes: (a) Diagrammatic section through a typical adult tooth. (b)Adult teeth. (c)Dental reference terms and normal teeth orientation. (d)Primary teeth. (e)Skull of a child, exposing unerupted permanent teeth. Keywords: tooth, crown, neck, root, pulp cavity, enamel, dentin, gingival sulcus, cementum, periodontal ligament, root canal, alveolar bone, apical foramen, alveolar vessels, nerve, incisor, cuspid, bicuspid, molar, canines, distal surface, medial surface, dental reference terms Human Anatomy, 3rd edition Prentice Hall, © 2001

The Pharynx and Esophagus Food enters the esophagus from the pharynx The esophagus is a muscular tube behind the trachea Food is moved by peristalsis from the pharynx to the stomach Cardiac sphincter separates esophagus from stomach Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition The Esophagus FG25_09A.JPG Title: The Esophagus Notes: (a)Low-power view of a section through the esophagus. (b)The esophageal mucosa. Keywords: esophagus, muscularis mucosae, mucosa, submucosa, adventitia, muscularis externa, stratified squamous epithelium, lamina propria Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition The Stomach Has the same 4 basic layers When the stomach is empty, the mucosa lies in large folds Rugae Pyloric sphincter separates stomach from small intestine Human Anatomy, 3rd edition Prentice Hall, © 2001

External Anatomy of the Stomach FG25_10A.JPG Title: The Stomach and Omenta Notes: (a) Surface anatomy of the stomach, showing blood vessels and relation to liver and intestines. (b)Radiograph of stomach and duodenum after swallowing barium solution to increase contrast. (c)Radiograph of pyloric region, pyloric valve, and duodenum. Keywords: stomach, surface, lesser curvature, gastroepiploic artery, greater curvature, omentum, hepatoduodenal ligament, hepatogastric ligament, duodenum, pylorus, rugae, pyloric sphincter, fundus, body Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition Anatomy of the Stomach FG25_11A.JPG Title: Gross Anatomy of the Stomach Notes: (a) External and internal anatomy of the stomach. (b)Anterior view of abdominal cavity. Keywords: stomach, gross anatomy, esophagus, fundus, cardia, longitudinal, circular, oblique, mucosa, gastroepiploic vessels, rugae, pylorus, pyloric sphincter, duodenum, lesser curvature, greater curvature Human Anatomy, 3rd edition Prentice Hall, © 2001

Histology of the Stomach Mucosa is simple columnar epithelium with goblet cells Mucosa is folded to form gastric pits Gastric glands secrete gastric juice Several kinds of cells in each gland produce substances that form the gastric juice Mucus cells Chief cells Parietal cells Enteroendocrine cells Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition The Stomach Wall FG25_13C.JPG Title: Abdominal Regions and Planes Notes: Diagrammatic view of the abdominal regions and planes. Keywords: abdominal regions, planes, epigastric, hypochondriac, umbilical, lumbar, inguinal, hypogastric, liver, stomach, pancreas, gallbladder, colon, appendix, small intestine, spleen, rectum Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition Gastric Gland FG25_13D.JPG Title: Abdominal Regions and Planes Notes: Diagrammatic view of the abdominal regions and planes. Keywords: abdominal regions, planes, epigastric, hypochondriac, umbilical, lumbar, inguinal, hypogastric, liver, stomach, pancreas, gallbladder, colon, appendix, small intestine, spleen, rectum Human Anatomy, 3rd edition Prentice Hall, © 2001

Functions of the Stomach Mechanical digestion Food reaches pylorus Chemical digestion Digestion of proteins Absorption No food Water, electrolytes Some drugs Alcohol Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition The Small Intestine About 18 feet long 3 regions The duodenum (= “12 fingers’ length”) About 8 inches long Common bile duct & pancreatic duct empty here The jejunum (= “empty”) About 8 feet long Most digestion occurs here The ileum About 9.5 feet long Most absorption occurs here Ends in the ileocecal valve Human Anatomy, 3rd edition Prentice Hall, © 2001

Regions of the Small Intestine FG25_14.JPG Title: Regions of the Small Intestine Notes: (a)The color coding indicates the relative sizes and positions of the duodenum, jejunum, and ileum. (b)Anterior view of abdominopelvic viscera Keywords: small intestine, regions, duodenum, jejunum, large intestine, ileum Human Anatomy, 3rd edition Prentice Hall, © 2001

Histology of the Small Intestine The lining is folded into circular pleats called plicae circulares The mucosal surface is folded into villi The epithelial cell membranes are highly folded into microvilli Intestinal glands are found in the crypts (“hidden place” – like gastric pits) at the base of villi Secrete intestinal juice Human Anatomy, 3rd edition Prentice Hall, © 2001

Histology of the Small Intestine FG25_15A.JPG Title: The Intestinal Wall Notes: (a) Characteristic features of the intestinal lining.(b) The organization of villi and the intestinal crypts.(c) Diagrammatic view of a single villus. (d)Panoramic view of small intestine wall. (e)Villi photomicrographs from jejunum. Keywords: villi, intestinal crypts, mucosa, muscularis mucosae, submucosa, muscularis externa, serosa, lacteal, lymphoid nodule, intestinal glands, submucosal plexus, lymphatic vessel, myenteric plexus, plica, goblet cell, lacteal, brush border Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition A Villus FG25_15C.JPG Title: The Intestinal Wall Notes: (a) Characteristic features of the intestinal lining.(b) The organization of villi and the intestinal crypts.(c) Diagrammatic view of a single villus. (d)Panoramic view of small intestine wall. (e)Villi photomicrographs from jejunum. Keywords: villi, intestinal crypts, mucosa, muscularis mucosae, submucosa, muscularis externa, serosa, lacteal, lymphoid nodule, intestinal glands, submucosal plexus, lymphatic vessel, myenteric plexus, plica, goblet cell, lacteal, brush border Human Anatomy, 3rd edition Prentice Hall, © 2001

Functions of the Small Intestine Chyme is further broken down Proteins Carbohydrates Fats Most absorption is in the small intestine Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition The Large Intestine – AKA colon About 4.5 feet long Mesocolon supports Begins with the cecum Appendix is attached Ascending colon Transverse colon Descending colon Sigmoid colon Colon connects to the rectum Rectum connects to the anal canal which empties to the exterior through the anus Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition The Large Intestine FG25_17A.JPG Title: The Large Intestine Notes: (a) Gross anatomy and regions of the large intestine.(b) The cecum and veriform appendix.(c) Detailed anatomy of the rectum and anus. Keywords: large intestine, cecum, ileocecal valve, epiploic appendages, ascending, colon, descending, colic flexure, transverse, omentum, haustra, taenia coli, sigmoid, ileocecal valve, rectum, anus, anorectal canal Human Anatomy, 3rd edition Prentice Hall, © 2001

Histology & Functions of the Large Intestine Mucosa - simple columnar epithelium (thin) Completion of absorption Formation of feces Lots of mucus glands Expulsion of feces from the body Human Anatomy, 3rd edition Prentice Hall, © 2001

Digestion in the Large Intestine Mechanical Regulated by the ileocecal valve Mixing and peristalsis Mass peristalsis Chemical Mucus secreted No enzymes Bacteria – prepare chyme for elimination Human Anatomy, 3rd edition Prentice Hall, © 2001

Feces Formation & Defecation Chyme is now solid or semi-solid - feces Large intestine absorbs any more water and electrolytes from feces Defecation Mass peristalsis pushes fecal material into rectum Rectum stretches Defecation reflex Human Anatomy, 3rd edition Prentice Hall, © 2001

Histology of the Large Intestine FG25_19.JPG Title: The Wall of the Large Intestine Notes: (a) Three-dimensional view of the colon wall. (b)Photomicrograph of colon, showing detail of mucosal and submucosal layers. Keywords: colon wall, taenia coli, epiploic appendages, haustrum, columnar epithelium, intestinal gland, muscularis mucosae, submucosa, muscularis externa, circular, longitudinal Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition Accessory Organs Liver Pancreas Gall bladder Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition The Liver Performs many life-sustaining functions, digestive and other. Location – under the diaphragm on the left Connected to the diaphragm by the falciform ligament Divided into lobes Right lobe Left lobe Caudate lobe Quadrate lobe Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition The Liver FG25_20C.JPG Title: Anatomy of the Liver Notes: (a) Horizontal section through the upper abdomen. (b)Horizontal section through upper abdomen; cadaver. (c)Anatomical landmarks; anterior liver surface. (d)Posterior surface of liver. Keywords: liver, horizontal, stomach, falciform ligament, caudate, lobe, inferior vena cava, aorta, spleen, sternum, kidney, right lobe, gallbladder, round ligament, left lobe, hepatic vein, hepatic portal vein, hepatic artery, quadrate lobe, common bile duct, porta hepatis Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition The Liver FG25_20D.JPG Title: Anatomy of the Liver Notes: (a) Horizontal section through the upper abdomen. (b)Horizontal section through upper abdomen; cadaver. (c)Anatomical landmarks; anterior liver surface. (d)Posterior surface of liver. Keywords: liver, horizontal, stomach, falciform ligament, caudate, lobe, inferior vena cava, aorta, spleen, sternum, kidney, right lobe, gallbladder, round ligament, left lobe, hepatic vein, hepatic portal vein, hepatic artery, quadrate lobe, common bile duct, porta hepatis Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition Histology of the Liver - Outside is a capsule - Composed of tiny lobules Each lobule is surrounded by liver cells and sinusoids Bile ducts run between liver cells Human Anatomy, 3rd edition Prentice Hall, © 2001

Histology and Blood Supply of the Liver FG25_21A.JPG Title: Liver Histology Notes: (a) Diagrammatic view of lobular organization. (b)Light micrograph; liver lobule. (c)Light micrograph; detail of portal area. Keywords: liver, lobular organization, connective tissue, hepatic artery, bile duct, hepatocytes, hepatic portal vein, interlobular septum, portal area, bile ductules, central vein, vile canaliculi, sinusoid Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition Functions of the Liver Produces bile – the primary digestive function Composition Water Bile salts Cholesterol Pigments Bilirubin Digestive function Emulsification of fats Human Anatomy, 3rd edition Prentice Hall, © 2001

Other Functions of the Liver Absorbs and stores iron, vitamins A, D, E, B7, K Detoxifies toxins and hormones Metabolizes proteins, carbohydrates, and lipids Removes bacteria from the blood Kupffer cells Produces plasma proteins Removes worn-out and damaged red blood cells Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition The Gallbladder Location – underside of the left lobe of the liver Function – to concentrate and store bile Gallstones Cholesterol in bile crystalizes, crystals fuse. Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition The Gallbladder FG25_22A.JPG Title: The Gallbladder and Associated Bile Ducts Notes: (a) A view of the inferior surface of the liver. (b)Common bile duct, hepatic duct, and cystic duct. (c) Radiograph of gallbladder, biliary ducts, and pancreatic ducts, anterior/posterior view. Keywords: gallbladder, liver, duodenum, fundus, body, neck, common bile duct, cystic duct, common hepatic duct, portal vein, hepatic artery, gastric artery, duodenal ampulla, pancreaticohepatic sphincter, pancreatic duct Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition The Pancreas - Location – in the curvature of the duodenum Connected to the duodenum by the pancreatic duct Produces pancreatic juic Functions Exocrine - digestion of all the nutrient groups Endocrine – production of insulin & glucagon Control level of blood glucose Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition The Pancreas FG25_23A.JPG Title: The Pancreas Notes: (a) Gross anatomy of the pancreas. (b)Diagrammatic view of pancreatic cellular organization; exocrine and endocrine regions. (c)Photomicrograph of pancreas; endocrine and exocrine regions. Keywords: pancreas, head, tail, lobule, transverse artery, body, pancreatic duct, accessory pancreatic duct, artery, endocrine, exocrine, islet, acinar Human Anatomy, 3rd edition Prentice Hall, © 2001