Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Digestive System Part II
Document related concepts
Transcript
Unit I: Metabolism Digestive System Part II Chapter 21 Tissue Table Digestive Organ Oral Cavity Pharynx Esophagus Stomach Small Intestine Large Intestine Anal Canal Epithelial Tissue Muscle Type pH Small Intestine Segments Duodenum Transverse colon (cut) Jejunum Ascending colon Descending colon Ileum Sigmoid colon Cecum Rectum • Nearly all chemical digestion and nutrient absorption occurs in small intestine Small Intestine • Duodenum -10 in. – neutralizes stomach acids, emulsifies fats, pepsin inactivated by pH increase, pancreatic enzymes • Jejunum - next 8 ft. – Simple columnar – Smooth muscle Jejunum Duodenum Circular folds • Ileum - last 12 ft. – lymphatic nodules – ileocecal junction Villi Ileum Peyer Patches Serosa Muscularis externa Submucosa Mucosa Muscularis mucosae Small Intestine - Surface Area • Circular folds - up to 10 mm tall – chyme flows in spiral path • Villi - 1 mm tall – contain blood vessels and lymphatics (lacteal) • nutrient absorption Circular folds Villi Columnar epithelial cell Mucous cell Lacteal Nerve • Microvilli 1 micron tall – brush border enzymes – Dextrinase – Glucoamylase – Maltase – Sucrase, lactase Capillary network Arteriole Lymphatic vessel Venule Lamina propria Muscularis mucosae Intestinal Crypts • absorptive cells, goblet cells and at base, rapidly dividing cells • Brunner’s glands • Secrete 1-2 L of intestinal juice/day • pH 7.4-7.8 Brunner’s Glands Gross Anatomy of Large Intestine • 500 ml of indigestible food residue/day • 5 ft long and 2.5 inches in diameter in cadaver • Appendix – columnar epithelium, goblet cells, WBC, and lymphocytes Microscopic Anatomy of Large Intestine • Mucosa - simple columnar epithelium – anal canal: non-keratinized stratified squamous • Muscularis Externa – smooth muscle − anal canal: skeletal • No circular folds or villi Simple columnar epithelium Intestinal gland Mucous cells Aggregated lymphoid nodule Muscularis mucosae Submucosa Muscularis Externa Circular layer Longitudinal layer Anatomy of Anal Canal • • • • 3 cm total length Anal columns Anal sinuses Internal & External anal sphincters Bacterial Flora and Intestinal Gas • Bacterial flora populate large intestine – ferment cellulose and other undigested carbohydrates; – synthesize vitamins B and K • Flatus (gas) – average person produces 500 mL per day – most is swallowed air – hydrogen sulfide, indole and skatole produce odor Accessory Organs: Liver, Gallbladder and Pancreas • All release important secretions into small intestine to continue digestion Gross Anatomy of Liver • 3 lb. organ located inferior to the diaphragm • Simple cuboidal epithelium • 4 lobes – falciform ligament – round ligament Hepatocytes Microscopic Anatomy of Liver Hepatic sinusoids Bile Hepatic Hepatic duct Portal vein Artery Hepatic Triad • Hepatic lobules (2mm by 1mm) • Sinusoids lined with fenestrated endothelium Liver Function: Overview Hepatocytes secrete bile into bile canaliculi Bile ductules hepatic bile ducts in the nearest Triad Central vein hepatic veins inferior vena cava. Kupffer, phagocytic cells, engulf pathogens, cell debris, and damaged blood cells. Also responsible for storing iron, some lipids, and heavy metals (such as tin or mercury). Hepatocytes regulate solute and nutrient levels and absorb or secrete molecules. Start Blood enters the hepatic sinusoids from hepatic portal vein and hepatic artery. Bile duct Branch of hepatic portal vein Branch of hepatic artery Ducts of Liver, Gallbladder, and Pancreas Right and left hepatic ducts Common hepatic duct Round ligament Gallbladder Cystic duct Hepatic portal vein and hepatic artery Liver Duodenum Common bile duct Stomach Common bile duct Pancreatic duct Pancreas Intestinal lumen Duodenal papilla Hepatopancreatic sphincter Pancreas Gallbladder and Bile • Gallbladder: 10 cm long • Bile: minerals, bile acids, cholesterol, bile Start pigments, fats and phospholipids – bilirubin meals, bile • intestinal bacteria convert to Between becomes more urobilinogen = brown color concentrated. – bile acid (salts) • enterohepatic circulation – hepatocytes liver CCK Lipid droplet Liver small intestine Duodenum Bile salt The liver secretes bile continuously —roughly 1 liter per day. CCK triggers dilation of the hepatopancreatic sphincter and contraction of the gallbladder. Gross Anatomy of Pancreas • Endocrine and exocrine gland – secretes insulin and glucagon – secretes 1500 mL pancreatic juice/day • Pancreatic juice: – Water, zymogens, enzymes, and sodium bicarbonate Pancreatic lobules Pancreatic duct Common bile duct Body of pancreas Accessory pancreatic duct (present in 3–10 percent of individuals) Head of pancreas Duodenal papilla Duodenum Tail of pancreas Pancreatic Acinar Cells Pancreatic duct Endocrine cells in pancreatic islet Cells of pancreatic acinus The exocrine pancreatic acini • Zymogens proteases – Trypsinogen trypsin – Chymotrypsinogen chymotrypsin – Procarboxypeptidase carboxypeptidase • Other enzymes – Amylase (starch) – Lipase (fat) – Ribonuclease (RNA) and deoxyribonuclease (DNA)
