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Lab 5 Digestion and Hormones of Digestion 7/16/2015 MDufilho 1 Figure 23.1 Alimentary canal and related accessory digestive organs. Mouth (oral cavity) Tongue* Parotid gland Sublingual gland Submandibular gland Salivary glands* Pharynx Esophagus Stomach Pancreas* (Spleen) Liver* Gallbladder* Transverse colon Small intestine Duodenum Jejunum Ileum Descending colon Ascending colon Cecum Sigmoid colon Rectum Appendix Anal canal Anus 7/16/2015 MDufilho Large intestine 2 Figure 23.2 Gastrointestinal tract activities. Ingestion Mechanical breakdown • Chewing (mouth) • Churning (stomach) • Segmentation (small intestine) Digestion Food Pharynx Esophagus Propulsion • Swallowing (oropharynx) • Peristalsis (esophagus, stomach, small intestine, large intestine) Stomach Absorption Lymph vessel Small intestine Large intestine Blood vessel Mainly H2O Feces Defecation 7/16/2015 Anus MDufilho 3 Figure 23.7a Anatomy of the oral cavity (mouth). Soft palate Palatoglossal arch Uvula Hard palate Oral cavity Palatine tonsil Tongue Oropharynx Lingual tonsil Epiglottis Hyoid bone Laryngopharynx Esophagus Trachea 7/16/2015 MDufilho Sagittal section of the oral cavity and pharynx 4 Figure 23.13 Deglutition (swallowing). Slide 1 Bolus of food Tongue Uvula Pharynx Bolus Epiglottis Epiglottis Glottis Upper esophageal sphincter Trachea Esophagus 1 During the buccal phase, the upper esophageal sphincter is contracted. The tongue presses against the hard palate, forcing the food bolus into the oropharynx. 2 The pharyngeal-esophageal phase begins as the uvula and larynx rise to prevent food from entering respiratory passageways. The tongue blocks off the mouth. The upper esophageal sphincter relaxes, allowing food to enter the esophagus. 4 Peristalsis moves food through the esophagus to the stomach. Relaxed muscles Circular muscles contract Bolus 3 The constrictor muscles of the pharynx contract, forcing food into the esophagus inferiorly. The upper esophageal sphincter contracts (closes) after food enters. Relaxed muscles 5 The gastroesophageal sphincter surrounding the cardial oriface opens, and food enters the stomach. Bolus of food Longitudinal muscles contract Circular muscles contract Gastroesophageal sphincter closed Gastroesophageal sphincter opens Stomach 7/16/2015 MDufilho 5 Figure 23.14a Anatomy of the stomach. Cardia Fundus Esophagus Muscularis externa • Longitudinal layer • Circular layer • Oblique layer Serosa Body Lumen Lesser curvature Rugae of mucosa Greater curvature Duodenum 7/16/2015 Pyloric sphincter (valve) at pylorus Pyloric canal MDufilho Pyloric antrum 6 Digestive Processes in the Stomach • Physical digestion • Denaturation of proteins by HCl • Enzymatic digestion of proteins by pepsin (and milk protein by rennin in infants) • Lingual lipase digests some triglycerides before digested as any other protein • Delivers chyme to small intestine 7/16/2015 MDufilho 7 Figure 23.19 Deglutition (swallowing). Pyloric valve closed 1 Propulsion: Peristaltic waves move from the fundus toward the pylorus. 7/16/2015 Slide 1 Pyloric valve slightly opened Pyloric valve closed 2 Grinding: The most vigorous peristalsis and mixing action occur close to the pylorus. MDufilho 3 Retropulsion: The pyloric end of the stomach acts as a pump that delivers small amounts of chyme into the duodenum, simultaneously forcing most of its contained material backward into the stomach. 8 Figure 23.1 Alimentary canal and related accessory digestive organs. Mouth (oral cavity) Tongue* Parotid gland Sublingual gland Submandibular gland Salivary glands* Pharynx Esophagus Stomach Pancreas* (Spleen) Liver* Gallbladder* Transverse colon Small intestine Duodenum Jejunum Ileum Descending colon Ascending colon Cecum Sigmoid colon Rectum Appendix Anal canal Anus 7/16/2015 MDufilho Large intestine 9 Figure 23.29a Gross anatomy of the large intestine. Left colic (splenic) flexure Right colic (hepatic) flexure Transverse mesocolon Transverse colon Epiploic appendages Superior mesenteric artery Descending colon Haustrum Ascending colon IIeum Cut edge of mesentery IIeocecal valve Tenia coli Sigmoid colon Cecum Appendix Rectum Anal canal 7/16/2015 External anal sphincter MDufilho 10 Figure 23.21 The duodenum of the small intestine, and related organs. Right and left hepatic ducts of liver Cystic duct Common hepatic duct Bile duct and sphincter Accessory pancreatic duct Mucosa with folds Tail of pancreas Pancreas Jejunum Gallbladder Major duodenal papilla Hepatopancreatic ampulla and sphincter 7/16/2015 Main pancreatic duct and sphincter Duodenum Head of pancreas MDufilho 11 Figure 23.28 Mechanisms promoting secretion and release of bile and pancreatic juice. 1 Chyme enter -ing duodenum causes duodenal enteroendocrine cells to release cholecystokinin (CCK) and secretin. 4 Bile salts and, to a lesser extent, secretin transported via bloodstream stimulate Liver to produce bile more rapidly. 5 CCK (via blood stream) causes gallbladder to contract and Hepatopancreatic Sphincter to relax. Bile Enters duodenum. 6 During cephalic and gastric phases, vagal Nerve stimulates gallbladder to contract weakly. 2 CCK (red dots) and secretin (yellow dots) enter the bloodstream. 3 CCK induces secretion of enzyme-rich pancreatic juice. Secretin causes secretion of HCO3− -rich pancreatic juice. 7/16/2015 Slide 1 CCK secretion Secretin secretion MDufilho 12