Digestive System PDF

LECTURE 7 Digestive System Outline: Functions Basic Histology Mesenteries Major divisions Accessory organs  Digestive System Functions 1.Ingestion 2.Mechanical processing Chewing 3.Digestion THE GUT TUBE 4.Secretion 5.Absorption 6.Excretion 7....

LECTURE 7 Digestive System Outline: Functions Basic Histology Mesenteries Major divisions Accessory organs  Digestive System Functions 1.Ingestion 2.Mechanical processing Chewing 3.Digestion THE GUT TUBE 4.Secretion 5.Absorption 6.Excretion 7.Compaction  Components of the Digestive System Major Subdivisions Mouth Oral Cavity Mechanical processing, moistening, Accessory Organs mixing with salivary secretions Pharynx Salivary Glands Muscular propulsion of materials Secretion of lubricating into the esophagus fluid containing enzymes Esophagus that break down Transport to the stomach carbohydrates Liver Secretion of bile (important Stomach for lipid digestion), storage Chemical breakdown of materials of nutrients via acid and enzymes; mechanical processing (muscular contractions) Gallbladder Storage and concentration Small Intestine of bile Enzymatic digestion and absorption Pancreas water, organic substrates, vitamins, ions Exocrine cells secrete buffers and Large Intestine digestive enzymes; endocrine Enzymatic digestion and absorption of cells secrete hormones water, organic substrates, vitamins, and ions Anus Figure 25.1  Histology of the Digestive Tract Plica Mesenteric artery and vein probably Mucosal epithelium Lamina Mucosa Mesentery Plica 1. Mucosa propria Villi Mucosal glands Submucosal gland Muscularis mucosae 2. Lymphatic vessel Submucosa Artery and vein Submucosal plexus 3. Muscularis Circular muscle layer externa Myenteric plexus Longitudinal muscle layer layers of the digestive tract a Three-dimensional view of the histological b An enlarged section of the digestive musosa, organization of the general digestive tube submucisa and tube showing the structure of a plica muscularis externa Figure 25.2  1 circular muscles , 2 longitudinal muscles, 3 circular pushes forward INITIAL STATE Peristalsis Longitudinal muscle Circular muscle From To mouth anus 1 contraction of circular Contraction muslces behind the bolus 1 L contraction of longtinudinal muslces ahead of the bolus 2 2 Contraction Contraction 3 contraction in circular muscle layer forces bolus forward 3 Figure 25.3  Segmentation 1 Segmentation 2 Small intestine and regions of the large intestine 3 invloves the circular muscle layers, they churn and mix the contents od the digestive tracts, but do not produce net movement in a particular direction 4 Figure 25.3b  hangs more around the internal organs acts as an apron Mesenteries & Omentum Fused double sheets of peritoneal membrane stops the entanglement of the digestive organs Function: stablizes the postion of the organs stabilizes the postion of blood vessels Provide the attachment of blood vessels going to and from the small intestine  Mesenteries & Omentum stomach to liver attached to the stomach Lesser Greater omentum omentum (cut) dorsal side ventral side located where the curvature is Transverse mesocolon Transverse Fusion fascia of ascending colon and descending colons fuses to dorsal peritoneum Ascending colon Mesentery proper Descending colon keep small intestine in place Small intestine Sigmoid colon Figure 25.4d  Falciform Diaphragm ligament Liver Text Lesser omentum Pancreas Stomach Duodenum Transverse mesocolon Mesentery Transverse colon proper Greater omentum Sigmoid mesocolon Parietal peritoneum Small Rectum intestine Urinary bladder Uterus Figure 25.4b  The Oral Cavity Hard Nasal cavity palate Soft palate Pharyngeal tonsil Opening of Entrance to parotid duct auditory tube Upper lip Nasopharynx Cheek Uvula Palatine tonsil Lower lip Fauces Gingiva Vestibule Oropharynx Body of Lingual tonsil tongue Epiglottis Laryngopharynx Hyoid bone Figure 25.5a  The Oral Cavity Frenulum of upper lip Hard palate Soft palate Fauces Pharyngeal Arches Uvula Palatoglossal arch Palatopharyngeal arch Palatine tonsil Tongue Lingual frenulum Gingiva Vestibule Openings of Frenulum of lower lip submandibular ducts Figure 25.5b  The Salivary Glands What cranial nerve controls the tongue?? hypoglossal nerves see the glands on the plastic model Parotid duct Openings of Salivary sublingual ducts Glands Parotid salivary gland Opening of left submandibular duct Sublingual salivary gland Submandibular Submandibular duct salivary gland this is apart of the mandibular 1-1.5L saliva/day Figure 25.6a  The Oral Cavity – Salivary Glands 1. Parotid salivary glands largest salivary gland Enzyme drains to the mouth via the parotid duct 2. Sublingual salivary glands Covered by the mucous membrane of the floor of the mouth numerous sublingual ducts that open along either side of the lingual frenulum 3. Submandibular salivary glands on the floor of the mouth, deep into the mandible and submandibular ducts  The Pharynx passageway for food, liquid, and air Pharyngeal muscles involved in swallowing: prevents food or liquid from going down the wrong tract 1. Pharyngeal constrictors - push the bolus toward the esophagus laryngeal lifts, so it doesnt 2. Laryngeal Elevators help with swallowing go down the wrong hole 3. Palatal - raise and tense the soft palate 1 Palatal Muscles Tensor veli palatini Levator veli palatini Laryngeal Elevators Stylopharyngeus Palatopharyngeus Pharyngeal Constrictors Superior pharyngeal constrictor Middle pharyngeal constrictor Inferior pharyngeal constrictor Esophagus Figure 10.8a  The Swallowing Process (deglutition) The first stage of swallowing and is a voluntary process. It begins when food enters the mouth and ends when the food reaches the pharynx: Esophageal Phase 1 Buccal Phase 3 Hard palate the stage when food moves through the esophagus and into the stomach Tongue 1 mouth to pharynx Soft palate 2 pharynx to esophagus Epiglottis 3 esophague to stomach Esophagus Larynx Peristalsis 2 Pharyngeal Phase Esophagus Thoracic cavity Diaphragm Stomach Pharyngeal phase - food moves through the throat soft palate , seals of the nasal cavity Figure 25.8  The Esophagus hollow muscular tube from the pharynx region to the stomach It is 25 cm long and 2 cm in diameter Located posterior to the trachea Enters the peritoneal cavity by passing through the esophageal hiatus of the diaphragm upper and lower esophageal sphincters  The Stomach Three major functions: 1. Bulk storage of ingested food 2. mechanical breakdown of ingested food 3. Chemical digestion of ingested food The end result is the production of chyme  know the layers of the stomach from outer to inner Anatomy of the Stomach fundas Esophagus superior to the junction Musculature of the between the stomach and the esophagus Stomach Longitudinal muscle layer Anterior Cardia surface superior, medial portion of Circular muscle layer the stomach close to gastroesophageal junction. Oblique muscle layer Body between the fundus and Lesser curvature the pylorus. (medial surface) Pyloric pyloris extends to the entrance to the sphincter Rugae duodenum. pyloric sphincter regulates Duodenum the into the duodenum. Greater curvature rugae allows the stomach to expand (lateral surface) Figure 25.10  Anatomy of the Stomach Lesser curvature (medial surface) Mesenteries Esophagus Diaphragm Lesser Omentum Fundus Spleen Cardia Hepatogastric STOMACH Left gastric artery Ligament Bod Left gastroepiploic Hepatoduodenal y artery Ligament Pylorus Right gastric artery Right gastroepiploic Greater Omentum artery Greater curvature (lateral surface) Gall bladder Right kidney Duodenum Transverse colon gastric artery then gastropiploic artery Figure 25.10  Histology of the Stomach Wall Esophagus Diaphragm Mucous Fundus Body Cardia epithelial Lesser curvature cells Lesser omentum Pylorus Greater omentum Entrances to gastric Greater curvature Rugae pits Gastric mucosa SEM x 35 a Diagrammatic view of the stomach and mucosa. b Colorized SEM of the gastric mucosa. Gastric pits: Mucous surface cells: make muscus to line the surface to protect the envirnoment Figure 25.12ab  Histology of the Stomach Wall Layers of the Stomach Wall Mucosa Gastric pit (opening to gastric gland) Mucous epithelium Lamina propria Muscularis mucosae Submucosa Artery and Muscularis externa vein Oblique muscle Circular muscle Lymphatic vessel Longitudinal muscle Myenteric plexus Serosa Histology of the Stomach Wall miss pretty girl cute in this order Mucous Gastric pit cells Mucin Cells of Gastric HCl lowers pH of gastric juice Glands Gastric Parietal Gastric Intrinsic Factor [Vitamin gland cells B12 uptake in small intestine ] G cell Chief cells Smooth muscle cell GASTRIN Muscularis hormone that helps prepare the digestive mucosae system for digesting and absorbing food Fig 25.12  The Small Intestine Approximately 20 feet long/ 1.5–2.5 inches diameter 1. Duodenum 10 inches long; receives digestive enzymes from the pancreas, bile from the liver and gallbladder 2. Jejunum 8 feet long; most of the digestion and absorption occurs in the jejunum 3. Ileum 12 feet long; controls flow of materials into the cecum (sphincter)  Transverse colon Regions of the Small Intestine Duodenum Jejunum Ileum Ascending colon Cecum Descending colon Sigmoid colon Rectum Figure 25.13  Histology of the Small Intestine Plicae consists of numerious microvilli within each villis are capillaries Absorb nutrients from the lumen of the small intestine into capillaries Intestinal crypts appear at the base of the villi new epithelial cells are formed in this area Contain enteroendocrine cells produce intestinal hormones, including cholecystokinin and secretin - digestions and appetite regulation produce enzymes with antibacterial activity villi helps with absorption Villi Intestinal Lymphoid Lacteal crypt nodule absorbs larger materials Layers of the Small Intestine Submucosal artery and vein Mucosa Lymphatic vessel Muscularis mucosae Submucosal plexus Submucosa Circular layer of smooth muscle Muscularis externa Myenteric plexus Serosa Longitudinal layer of smooth muscle b The organization of villi and the intestinal crypts Figure 25.14b  Histology of the Small Intestine Goblet cell Each villus contains a lacteal Columnar epithelial lacteals absorb materials that cannot be cell absorbed by the capillaries Examples would be large lipid- protein complexes Lacteal Nerve Capillary network Lamina propria Arteriole Venule Lymphatic vessel Figure 25.14c  unique feature of each regions Regions of the Small Intestine Jejunum Serosa Duodenum Muscularis Duodenal externa submucosal Plicae Submucosa glands Mucos the gland a uscularis M nuetralizes the Vill mucosae gastric acid. i jejunum has a Cause it contains the digestive lot because it enzymes deos absorption of food and nutrients Aggregated lymphoid Ileum nodules (Peyer’s patches) lot of immune cells in the module Fig 25.15  The Large Intestine reabsorption of water and contains fecal matter Approximately 5 feet in length, 3 inches in diameter Functions reabsorption of water Results in compaction of waste (forms feces) Absorption of vitamins produced by the housed bacteria storage of fecal material prior to defecation  TRANSVERSE COLON Left colic Right colic (hepatic) (splenic) flexure flexure DESCENDING COLON ASCENDING COLON Omental appendices Haustra (pouches) Ileocecal valve Ileum Cecum Taenia coli Appendix (smooth muscle) Sigmoid flexure SIGMOID COLON Rectum Figure 25.16a  The Large Intestine the hepatic flexure and splenic flexure are like the shoulders of The Colon the large intestine – Waste material leaves the ileum and enters the cecum Waste material goes “up” the ascending colon Around the hepatic flexure “Across” the transverse colon Around the splenic flexure “Down” the descending colon Around the sigmoid flexure To the sigmoid colon Into the rectum  The Large Intestine The Colon – the wall of the colon has pouches that allow for expansion called haustra – Longitudinal muslces called taeniae coli aid in the process of peristalsis – The serosa of the large intestine has numerous “flaps” of sacs of fat attached to but extending from the intestine called omental appendices  The Large Intestine The Rectum – temporary stores waste matter – The last portion of the rectum is the anal canal The anal canal consists of anal columns The anal canal ends at the anus  Rectum skeletal voluntary, smooth involuntary Anal canal Anal columns Internal anal sphincter (smooth muscle) External anal sphincter (skeletal muscle) Anus Figure 25.16c  Histology of the Large Intestine thinner than the walls of the small intestine No villi numerous goblets cells ( they secrete mucus) distinctive intestinal crypts – produces mucus to lubricate undigested material Contains large lymphoid nodules  Taenia coli Omental appendices Haustrum Lymphoid Simple columnar nodule epithelium Layers of the Large Intestine Goblet cells Mucosa Intestinal crypt Muscularis mucosae Submucosa Muscularis externa Circular layer Longitudinal layer Serosa a Diagrammatic view of the colon wall Figure 25.18a  Accessory Organs of Major Subdivisions of the Digestive Tract the Digestive System Mouth Oral Cavity Mechanical processing, moistening, Salivary Glands mixing with salivary secretions Secretion of lubricating Pharynx fluid containing enzymes Muscular propulsion of materials into the that break down esophagus carbohydrates Esophagus Transport of materials to the stomach Liver Secretion of bile (lipid Stomach digestion), storage of Chemical breakdown of materials via acid nutrients, and enzymes; mechanical processing Gallbladder through muscular contractions Small Intestine Storage and Enzymatic digestion and absorption of concentration of bile water, organic substrates, vitamins, and ions Large Intestine Pancreas Enzymatic digestion and absorption of Exocrine cells secrete water, organic substrates, vitamins, and ions buffers and digestive enzymes; endocrine cells Anus secrete hormones Accessory Glandular Digestive Organs The Liver – The largest visceral organ of the body – The liver is involved in: Metabolic regulation - stores glycogen, fat and protein metabolism Hematological regulation - storage of blood Bile production breaks -down fats into fatty acids  Anatomy of the Liver Coronary ligament Connected to diaphragm the left points laterally There is 3 Right lobe ligaments of Left lobe the liver Falciform ligament Round ligament Gallbladder right has that point inferior c Anatomical landmarks on the anterior surface of the liver Fig 25.19  Anatomy of the Liver identify these things and whats in the porta heptasis Left hepatic vein Coronary ligament Inferior vena cava Caudate lobe Left lobe Porta Hepatis Hepatic portal vein Hepatic artery proper Right lobe Common bile duct Quadrate lobe Gallbladder d The posterior surface of the liver it spells vad - vein, artery and duct Fig 25.19  The Hepatic Portal System Inferior vena cava Aorta Stomach Left gastric Right gastric Hepatic portal Left gastroepiploic supply nutrients to the intestine Right gastroepiploic Pancreas Splenic Pancreatic Superior mesenteric Inferior mesenteric Fig 22. 22  plastic models in the lab Liver Histology (hepatocytes) Central vein Sinusoid Hepatic Triad Interlobular Bile Branch of Portal Bile septum duct hepatic portal vein area (6) ductules Liver lobules = functional unit of the liver Fig 25.2 Histological Organization of the Liver Spaces are created between the lines of hepatocytes; these spaces are called sinusoids Sinusoids consist of: Capillaries: leading to the central vein Kupffer cells: phagocytic cells of the liver kupffer job is to clean, mainly to clear pathogen and debris from the blood in the liver  Liver Histology Central vein Kupffer cells Sinusoid Bile canaliculi Branch of hepatic portal vein Bile Branch of hepatic Hepatocytes duct artery proper Fig 25. 20  The Gallbladder The gallbladder is divided into three regions Fundus Body Neck The cystic duct leads from the neck of the gallbladder to the common bile duct Function – storage of bile – bile modification  plastic model identify different parts Left hepatic duct Round ligament Left hepatic Right hepatic duct artery Cystic duct Common Gallbladder hepatic duct Fundus Cut edge of lesser Body omentum Neck Hepatic portal vein Common bile Common duct hepatic Liver artery Duodenum Right gastric artery Stomach Pancreas Fig 25.21  The Gallbladder and Associated Bile Ducts Hepatopancreatic sphincter Common bile duct Duodenal ampulla Duodenal papilla Pancreatic duct Intestinal lumen Pancreas c A portion of the lesser omentum has been cut away to make it easier to see the relationships among the common bile duct, the hepatic duct, and the cystic duct. Fig 25.21  The Pancreas – posterior to the stomach The pancreas consists of: Head: nearest the curvature of the duodenum Body: extends toward the spleen Tail: rounded end of the pancreas nearest the spleen Pancreatic duct: delivers secretions from the pancreas to the duodenum (through the hepatopancreatic sphincter)  Tail of pancreas plastic model Splenic artery Great pancreatic Caudal pancreatic artery artery Abdominal aorta Stomach Common bile duct Accessory pancreatic duct (to lesser duodenal papilla) Lobules Duodenum Transverse Body of pancreatic artery Head of pancreas pancreas Pancreatic duct to greater Superior mesenteric duodenal papilla) with artery common bile duct Anterior branch Inferior pancreatico- Posterior duodenal artery branch Fig 25.22  Histology of the Pancreas Consists of lobules Within each lobule are: Acinar cells – Produce digestive enzymes – Enzymes travel through the pancreatic duct to the small intestine Pancreatic islets – Produce hormones – hormones enter the bloodstream to target to target organs  Pancreatic Acinar cells Pancreatic islet duct (exocrine) (endocrine) Pancreatic acini Diagrammatic view of the histological organization of the pancreas showing exocrine and endocrine regions. Fig 25.22  Lab exams identify cells, tissues and what organ it comes from Duct Pancreatic acini (exocrine) Pancreatic islet (endocrine) Pancreas LM x 120 c Histology of the pancreas showing exocrine and endocrine cells.  Pancreatic Enzymes Pancreatic Enzymes (from Acinar Cells) – Lipases Digest lipids – Carbohydrases Digest carbohydrates – Nucleases Digest nucleic acids – Proteinases Digest protein  Pancreatic Hormones Pancreatic Hormones (from Pancreatic Islets) – Insulin regulates blood sugar, moves glucose into cells – Glucagon ???? google later – Somatostatin Charles Best – student helper James Collip - biochemist John JR McCleod - supervisor Frederick Banting Nov 14, 1891 – Feb 21 1941  Components of the Digestive System Major Subdivisions Mouth Oral Cavity Mechanical processing, moistening, Accessory Organs mixing with salivary secretions Pharynx Salivary Glands Muscular propulsion of materials Secretion of lubricating fluid into the esophagus containing enzymes that Esophagus break down carbohydrates Transport of materials to the Liver stomach Secretion of bile (important Stomach for lipid digestion), storage Chemical breakdown of materials via of nutrients, many other acid and enzymes; mechanical vital functions processing through muscular Gallbladder contractions Storage and concentration Small Intestine of bile Enzymatic digestion and absorption of Pancreas water, organic substrates, vitamins, and ions Exocrine cells secrete buffers Large Intestine and digestive enzymes; Enzymatic digestion and absorption of endocrine cells secrete water, organic substrates, vitamins, and ions hormones Anus Figure 25.1 Questions?