3Overview Digestive System Alimentary Canal (Gastrointestinal Tract) The continuous tube that carries foodfrom the mouth to the anus.
4Overview Digestive System Alimentary Canal (Gastrointestinal Tract) The continuous tube that carries foodfrom the mouth to the anus.Accessory Digestive OrgansOrgans that contribute to the digestionof food even though food does not passdirectly through these organs.
6Overview Digestive Processes Mechanical Digestion: The physical breakdown of food.Ex: Grinding of the teeth or churning of the stomach.
7Overview Digestive Processes Mechanical Digestion: The physical breakdown of food.Ex: Grinding of the teeth or churning of the stomach.Chemical Digestion: The catabolic breakdown of food usingenzymes and acids.
8Overview Digestive Processes Mechanical Digestion: The physical breakdown of food.Ex: Grinding of the teeth or churning of the stomach.Chemical Digestion: The catabolic breakdown of food usingenzymes and acids.Absorption: The passage of digested food from the lumen ofthe GI Tract into the blood or lymph.
19Mouth Salivary Glands: Moisten food and contain enzymes for the breakdown of starchy foods.
20Salivary GlandsThree pairs of major salivary glands (parotid, submandibular, and sublingual glands) and numerous smaller ones secrete saliva into the oral cavity, where it is mixed with food during mastication. Saliva contains water, mucus, and enzyme amylase.Functions of saliva include the following:It has a cleansing action on the teeth.It moistens and lubricates food during mastication and swallowing.It dissolves certain molecules so that food can be tasted.It begins the chemical digestion of starches through the action of amylase, which breaks down polysaccharides into disaccharides
21PharynxCommon passageway for food and air.Pharynx
22EsophagusPropels food to the stomach via “peristalsis.”Esophagus
23StomachStorage of food and digestion of protein.Stomach
24Stomach (in detail)CurvaturesLesserCurvatureGreaterCurvature
25Stomach (in detail) Sphincters Gastroesophageal Sphincter Pyloric
26Stomach (in detail)RegionsFundusBodyPyloricAntrum
27Stomach (in detail) Rugae: Large, longitudinal folds of the mucosa
28Small IntestineMajority of digestion and absorption occurs here.
29Small Intestine - Sections DuodenumFirst 10 inches of the small intestine.Collects bile from the liver.Collects pancreatic juices from the pancreas.“Sphincter of Oddi” controls entry of the bile and juices.
30Small Intestine - Sections Jejunum - Next 8 feet.Ileum - Final 12 feet.Ileocecal Valve - The small intestine joinsthe cecum of the large intestine.
31Large Intestine (“Colon”) Absorbs water and some nutrients.Large Intestine
33Large Intestine - cont. Taniae coli: Smooth muscle that causes the colon to “pucker.”Haustra: Pocket-like sacs.Appendix: Containslymphoid tissue that aidsthe immune system.
34Accessory Organs of Digestion Liver: Produces bile to aidin the digestion of lipids.
35Accessory Organs of Digestion Gallbladder: Stores bile untilit is released into the smallintestine.
36Bile Secretion in Detail The liver is stimulated by the hormones “secretin” and“cholecystokinin” (CCK) to produce bile.The bile enters the right and left hepatic ducts and travels to thecommon hepatic duct. The bile is stored in the gallbladder.The gallbladder is stimulatedto release the bile by thevagal nerve and CCK.The bile enters theduodenum via thebile duct.Right and left hepatic ductsCommon hepatic ductGallbladderBile ductDuodenum
37Accessory Organs of Digestion Pancreas: Produces many typesof enzymes used in the smallintestine to digest food.
38Pancreatic Juice Secretion in Detail The hormones cholecystokinin and secretin stimulate the release ofpancreatic juices by the pancreas.The juices travel through the pancreatic ducts to enter theduodenum.PancreasDuodenumMain pancreatic duct
39Control of Digestion - Nervous System Two Phases:“Cephalic Phase” - Triggered by the site,smell, and taste of food. This stimulates thestomach to prepare for the entry of food.
40Control of Digestion - Nervous System Two Phases:“Cephalic Phase” - Triggered by the site,smell, and taste of food. This stimulates thestomach to prepare for the entry of food.“Gastric Phase” - Stomach distension by foodstimulates the release of gastric juices.
41Control of Digestion - Hormones Gastrin - Produced by the stomach; stimulatesthe release of gastric juices.
42Control of Digestion - Hormones Gastrin - Produced by the stomach; stimulatesthe release of gastric juices.Secretin - Produced by the small intestine;stimulates the pancreas and gall bladder to releasepancreatic juices and bile.
43Control of Digestion - Hormones Gastrin - Produced by the stomach; stimulatesthe release of gastric juices.Secretin - Produced by the small intestine;stimulates the pancreas and gall bladder to releasepancreatic juices and bile.Cholecystokinin (CCK) - Produced by the smallintestine; stimulates the pancreas and gall bladderto release pancreatic juices and bile.
45Peptic Ulcer Lesions in the wall of the stomach or duodenum. Digestive DisordersPeptic UlcerLesions in the wall of the stomachor duodenum.Primarily caused by bacteria.Treated with antacids ANDantibiotics.
46Appendicitis Usually caused by fecal obstruction Digestive DisordersAppendicitisUsually caused by fecal obstructionor anatomical “kinking” of theappendix.A rupture leads to peritonitis (ouch)
47(Inflammation of the Peritoneum) Digestive DisordersPeritonitis(Inflammation of the Peritoneum)Usually results from an infection caused by aexternal or internal penetrating wound.Bacteria from intestinesenter the sterile areas of the bodysurrounding the digestive system.May cause death if not treated with highdoses of antibiotics.
49(Inflammation of the liver) Digestive DisordersHepatitis(Inflammation of the liver)Caused by drugs, chemicals, viruses,alcohol, etc.Viral “Hepatitis A” is usually causedby the ingestion of food.Viral “Hepatitis B” and “Hepatitis C”are “blood-borne” pathogens.
50Diverticulitis Small bulges (herniations) of the mucosa in Digestive DisordersDiverticulitisSmall bulges (herniations) of the mucosa inThe large intestine.These areas can become inflamed andpossibly rupture.Prevention is the treatment of choice. Adiet high in fiber will help preventdiverticulitis.
52Emesis (Vomiting) Can be caused by microbes, allergies, Digestive DisordersEmesis(Vomiting)Can be caused by microbes, allergies,gluttony, poisons, etc.
53Diarrhea Movement of fecal material through the GI Tract too rapidly. Digestive DisordersDiarrheaMovement of fecal material throughthe GI Tract too rapidly.May be caused by microbes, spicyfoods, stress, etc.
54Constipation Infrequent defecation of fecal material. Digestive DisordersConstipationInfrequent defecation of fecalmaterial.Usually caused by a diet low infiber and water.
55Cirrhosis of the Liver Condition where liver cells are Digestive DisordersCirrhosis of the LiverCondition where liver cells aredestroyed and replaced by fibrousconnective tissue.Alcoholism is a common cause ofcirrhosis.
56Gall Stones (Biliary Calculi) Crystalization of cholesterol and bile Digestive DisordersGall Stones(Biliary Calculi)Crystalization of cholesterol and bilesalts.Blocks the bile duct or fills the gallbladder.
57Gallstones: MRI showing transverse section of abdomen
58Jaundice Build-up of bile in the skin causing a yellowing of the skin. Digestive DisordersJaundiceBuild-up of bile in the skin causinga yellowing of the skin.May be caused by damage to the liver,gall bladder, or any of the ducts thatservice these organs.
60Buliemia Nervosa Condition where a patient binges on Digestive DisordersBuliemia NervosaCondition where a patient binges onfood and then purges with eitherlaxatives or vomiting.Considered a psychological disorderwhere the patient has a fear of gainingweight.Treated with psychotherapy.
61Anorexia Nervosa Digestive Disorders Psychological disorder where the patienthas a false perception of their own weight.Patient denies their own appetite.Patients are usually % below normalbody weight.Extreme cases are lethal.Closely associated with bulimia nervosa.
62False perception of my weight. It should never be considered “fashionable”It can affect men and women
63Flatulence Excessive intestinal gas resulting Digestive DisordersFlatulenceExcessive intestinal gas resultingfrom bacteria in the intestines, diet,or swallowing air.