Transcript Chapter 38
Exercise 41 Digestive System 1 Digestion and absorption 2 It is the physical and chemical break down of food Absorption It is the passing of the digested food through the epithelial cells into the blood stream Digestive system 3 Gastrointestinal tract 4 It is the alimentary canal Mouth Pharynx Esophagus Stomach Small intestine Large instestine Accessory digestive organs 5 Salivary glands Gallbladder Liver Pancreas Teeth General histology of the gastrointestinal tract 6 It has 4 tunics Mucosa • Epithelium – simple columnar • Lamina propria – areolar tissue • Muscularis mucosa • Smooth muscle that enables movement of the mucosa General histology of the gastrointestinal tract 7 • Functions of the mucosa are secretion, absorption, protection Submucosa • Dense connective tissue • Blood vessels • Lymph nodes and vessels • Submucosal plexus • Functions are nutrition and protection of the mucosa General histology of the gastrointestinal tract Muscularis externa • Inner circular layer of smooth muscle • Outer longitudinal layer of smooth muscle • Myenteric plexus • Allows GI movements 8 General histology of the gastrointestinal tract Serosa 9 (abdominal organs) • Most outer layer • Mesothelium – areolar tissue • Functions is to reduce friction between GI organs Adventitia • Coarse fibrous tissue that binds the GI organs to the surrounding tissues. Anchors and protects them Oral cavity 10 Macroscopy of the digestive tract Oral cavity or mouth Oral cavity Lips or labia • Superior and inferior labial frenulum Cheeks Palate • Soft with uvula • Hard • Palatine raphe 11 Macroscopy of the digestive tract Tongue • Lingual frenulum Vestibule Palatine tonsil • Palatoglossal arch • Palatopharyngeal arch 12 Macroscopy of the digestive tract Lingual 13 tonsil Salivary glands • Saliva • Salivary amylase Pharynx Nasopharynx Oropharynx Laryngopharynx Macroscopy of the digestive tract 14 Esophagus Peristalsis Gastroesophageal sphincter Adventitia and not serosa Stomach Cardiac region Fundus Body Macroscopy of the digestive tract Pyloric region • Pyloric sphincter Greater curvature Greater omentum • From the greater curvature down to the abdominal organs Lesser curvature 15 Macroscopy of the digestive tract Lesser omentum From the lesser curvature to the liver Gastric pit Gastric rugae Function of the stomach is to process the food forming the chyme 16 Histology of the stomach 17 Histology of the stomach 18 Mucosa Gastric glands • Chief or zymogenic cells: • Located on the fundus • Produce pepsinogen Histology of the stomach 19 • Parietal cells: • Located on the fundus • Produce HCL • Produce intrinsic factor Enteroendocrine cells: • Located on the pyloric region • Release hormones Submucosa Histology of the stomach 20 Muscularis externa Oblique layer Circular layer Longitudinal layer Gastroesphageal junction (Cardioesophageal) Stratified squamous epithelium on the esophagus Simple columnar on the stomach Small intestine 21 From the pyloric sphincter to the ileocecal valve Mesentery Proper • Double layer of peritoneum that attaches the small intestine to the posterior body wall Small intestine 22 Plicae Deep folds of the mucosa and submucosa They cause the chyme to spiral through the intestine slowing and mixing it Intestinal crypts of crypts of Lieberkuhn It is the invaginated area of the mucosa between the villi Small intestine 23 Lacteal It is the lymphatic capillary present in each villus Function of the small intestine Nutrients absorption PART B 24 Subdivisions of the small intestine 25 Small intestine 26 Duodenum Pancreatic duct Bile duct Hepatopancreatic ampulla Major duodenal papilla Hepatopancreatic sphincter or sphincter of Oddi Duodenal glands or Brunner’s glands – located in the submucosal layer Small intestine 27 Jejunum Where the food is most absorbed Ileum Ileocecal valve Peyer’s patches • Aggregation of lymphoid tissue more prominent in the ileum Small intestine 28 Superficial structures of the small intestine that increases the absorptive area of the mucosa Villi • Fingerlike projections of the mucosa Small intestine Microvilli or brush border • Projections of the cell membrane of the columnar epithelium • Brush border enzymes Plicae 29 Histology of the small intestine 30 Identify these structures on the slide: Plica Cripts Villi Brush border Layers of the intestine Histology of the small intestine 31 Duodenum Submucosa with Brunner’s glands Jejunum Longest, leafy villi Ileum Submucosa with Peyer’s patches The large intestine 32 Large intestine 33 From the ileocecal valve to the anus Mesocolon Attaches the large intestine to the body wall Cecum It is the first part Appendix A blind tube like structure connected to the cecum Large intestine 34 Colon: Ascending Right side of the abdominal cavity Right colic (hepatic) flexure It is retroperitoneal Transverse Cross the abdominal cavity Left colic (splenic) flexure Large intestine 35 Descending It is retroperitoneal Sigmoid S-shaped Located in the pelvis Rectum Large intestine 36 Anus External sphincter - skeletal muscle • Voluntary Internal sphincter – smooth muscle • involuntary Large intestine - structures 37 Tenia coli It is the longitudinal muscle layer of muscularis externa It is in the shape of a muscle band Haustra Pocket like sacs of the large intestine It is caused by the tenia coli Large intestine - structures 38 Epiploic appendages Fat-filled pouches of visceral peritoneum hanging for the colon’s surface Large intestine 39 Functions of the large intestine Consolidate and propel the fecal matter to the anus Site for intestinal bacteria to synthesize vitamins B and K Site for water absorption Histology of the large intestine 40 Lumen Crypts Layers of the digestive tract Mucosa with the maximum amount of goblet cells No villi Accessory digestive organs 41 Teeth: Deciduous (milk teeth) • They appear between 6 month and 2 ½ years of age • They begin to shed at 6 years of age • They are completely shed by the age of 12 Accessory digestive organs Permanent • They begin to appear at 6 years of age • They last for a lifetime 42 Types of teeth 43 Accessory digestive organs 44 Classification of the teeth Incisors • Chisel shaped • Shearing action when biting • 4 superiors and 4 inferiors (2 centrals and 2 laterals) • Single-rooted Accessory digestive organs 45 Canines Cone-shaped It tears the food 2 superiors and 2 inferiors Single-rooted Accessory digestive organs 46 Premolars Two cusps It grinds the food 4 superiors and 4 inferiors • 2 first premolars • 2 second premolars Generally single-rooted • 1st premolar may have 2 roots Accessory digestive organs 47 Molars They have broad crowns Rounded cusps 6 superiors and 6 inferiors • 2 first molars • 2 second molars • 2 third molars or wisdom teeth They have 2 roots They grind food into fine pieces Accessory digestive organs 48 Dental formula: Deciduous 2,1,0,2 2,1,0,2 Permanent 2,1,2,3 2,1,2,3 Accessory digestive organs 49 Anatomy of the teeth Crown • Clinical • Anatomical Enamel • It consists mainly of calcium salts Gum or gingival • Gingival sulcus and margin Accessory digestive organs 50 Neck Root Cementum Periodontal ligament Dentin Pulp Contain blood vessels and nerves Pulp cavity Accessory digestive organs 51 Odontoblasts Root canal Apical foramen PART C 52 Accessory digestive organs 53 Salivary glands Parotid glands • Anterior to the ear • He parotid duct open at the level of the second superior molar • Mainly a serous gland Accessory digestive organs Submandibular gland • Located on the floor of the mouth • He submandibular duct opens at the base of the lingual frenulum • Serous and mucous gland 54 Accessory digestive organs 55 Sublingual gland Located on the floor of the mouth There are many sublingual ducts that open under the tongue Serous and mucous gland Saliva composition Mucin - Forms the bolus Serous fluid – contain amylase Accessory digestive organs 56 Histology of the salivary glands Mucous cells forming the acini Serous cells forming demilunes around the mucous cells Ducts with cuboidal epithelium Salivary glands 57 Accessory digestive organs 58 Liver Located mainly in the right hypochondriac region 4 lobes • Right, left, caudate, quadrate Falciform ligament • Suspend the liver from the diaphragm and anterior abdominal wall Bile duct system 59 Accessory digestive organs 60 Bile Produced by the liver Responsible for emulsification of the lipid from the diet Bile duct system Bile canaliculus • Carries the bile to the duct of the nearest portal area Accessory digestive organs Bile ducts carry bile to the: Right and left hepatic ducts Common hepatic duct 61 Accessory digestive organs 62 Histology Lobules • Structural and functional units of the liver • They have cords of hepatocytes running away from the central vein • Hexagonal shape Central vein Histology of the liver 63 Accessory digestive organs Portal triad or portal tract • Located at each of the six corners of the lobule • Hepatic artery • Hepatic portal vein • Bile duct Sinusoids • Blood-filled Kupffer cells • Macrophage lining the sinusoids 64 Accessory digestive organs 65 Gallbladder Stores the bile not being used Concentrates the stored bile Cystic duct Accessory digestive organs 66 Pancreas It is a retroperitoneal organ Endocrine and exocrine organ Secretes the pancreatic juice into the duodenum It alkalinizes the chyme coming from the stomach Pancreatic duct or duct of Wirsung Accessory pancreatic duct or duct of Santorini Accessory digestive organs 67 Histology of the pancreas Acinar or exocrine pancreas Islets or endocrine pancreas Septa • Connective tissue Microscopic structures to be identified 68 Identify the organ and its layers: Mucosa, submucosa, muscularis externa, adventitia or serosa Esophagus Stratified squamous epithelium Gastroesophageal junction Microscopic structures to be identified 69 Stomach Simple columnar epithelium Gastric pit Duodenum Villi • Brush border • Goblet cells Intestinal cripts Brunner’s glands Microscopic structures to be identified 70 Jejunum Leafy villi, crypts Brush border Goblet cells Ileum Villi with goblet cells and brush border, crypts Peyer’s Patch Microscopic structures to be identified 71 Large intestine Cripts, abundant goblet cells Salivary glands Serous acini (demilunes) Mucous acini Ducts Pancreas Acinar exocrine vs. endocrine pancreatic islets Microscopic structures to be identified 72 Liver Hexagonal lobules Triad • Hepatic portal vein • Hepatic artery • Bile duct Central vein Sinusoids vs. plates of hepatocytes Cat structures to be identified 73 Esophagus Stomach Lesser and greater curvatures Lesser and greater omentum Small intestine Mesentery proper Ileocecal valve Cat structures to be identified 74 Large intestine Mesocolon Rectum Anus Liver Gall bladder Pancreas