DigestivetractHongya SunYangzhou University
1 Digestive tract Hongya Sun Yangzhou University
Introduction ofdigestivesystemOrganizationofdigestivesystem> consists of a long convoluted tube extending from themouth to the anus and a number of associated glands>thedigestivesystemconsistsoftwomajorsections--digestivetract:oral cavity, pharynx, esophagus, stomach,small intestine, large intestine, rectum and anus-digestiveglands(associatedglands):large gland: salivary glands, pancreas, liversmall gland:fundus gland, small intestinal gland,eto
2 Introduction of digestive system Organization of digestive system consists of a long convoluted tube extending from the mouth to the anus and a number of associated glands. the digestive system consists of two major sections -digestive tract: oral cavity, pharynx, esophagus, stomach, small intestine, large intestine, rectum and anus -digestive glands (associated glands ): large gland: salivary glands, pancreas, liver small gland: fundus gland, small intestinal gland, etc
ORGANS:ACCESSORYORGANS:Mouth·Teeth chewfood·TonguepositionsandtastesfoodPharynx-Passagewayfortood andair-Participates in swallowingSalivaryglands?Saliva moistens foodEsophagus·Bicarbonate maintainspH-Movesfoodfrompharynx-Amylase digosts starchtostomach-Lysozyme inhibits bacteriaStomachLiver-Stores and mixesfood-Produces bile-Begins chemical digestion of-Perfoms various functionsproteinbyenzymesandacidassociatedwithprocessing*Regulates deliverytotheand storing nutnientssmall intestineGall bladderLarge intestine-Stores and concentrates bile-Absorbs nutrients?Stores waste materialPancreasSecreles digestive enzynesSmall intestineinto small intestineDigestsproteins,fats-Secretes bicarbonate intoand carbohydratessmal intestine to neutralize-Absorbsmostofthenutrentsstomach acidSecretesdigestivehomonesand enzymesRectum-PassagowayfortecesAnusExpells undigested materialOutlineof DigestiveSystem
3 Outline of Digestive System
Outlineof MainFunctionof DigestiveSystemMechanicalprocessingandmovement:--chewing,mixing,etc.:Secretion:--fluid, bile, acid, alkali, mucus, digestive enzymes and hormones, etcDigestion:physical/chemical--breakingdownfoodtosmallest absorbable units (small molecules):Absorption:--through mucosa, into blood or lymph vesselsElimination:-undigestedmaterialeliminated
4 Outline of Main Function of Digestive System v Mechanical processing and movement: -chewing, mixing, etc. v Secretion: -fluid, bile, acid, alkali, mucus, digestive enzymes and hormones, etc. v Digestion: physical/chemical -breaking down food to smallest absorbable units (small molecules ) v Absorption: -through mucosa, into blood or lymph vessels v Elimination: -undigested material eliminated
Digestive tract
5 Digestive tract
OBJECTIVESThischaptershouldhelpyouto:Masterthe nameof the 4 layers that form thewalls of the tubularorgans of the digestive tract and the tissuetypes found in eachlayer.VMaster the distinguishing structural features and relatedfunctions of thevarious regions of each of the tubular organs ofthedigestivetract (i.e.esophagus,stomach,small intestine,large intestine),>Know the histological structure of the oral mucosa,the tongueand taste bud.>Knowthecomponents,structureandfunctionofthegutassociatedlymphoidtissue.6
6 OBJECTIVES This chapter should help you to: Master the name of the 4 layers that form the walls of the tubular organs of the digestive tract and the tissue types found in each layer. Master the distinguishing structural features and related functions of the various regions of each of the tubular organs of the digestive tract (i.e. esophagus, stomach, small intestine, large intestine). Know the histological structure of the oral mucosa, the tongue and taste bud. Know the components, structure and function of the gut- associated lymphoid tissue
Digestive tractOutlineI.General structure of digestive tractII.TongueIII.EsophagusIV.StomachV.SmallintestineVI.Large Intestine
7 Ⅰ. General structure of digestive tract Ⅱ. Tongue Ⅲ. Esophagus Ⅳ. Stomach Ⅴ. Small intestine Ⅵ. Large Intestine Outline Digestive tract
Aphotomicrograph of a histologicalOsection ofthestomach.1.Mucosa2.Submucosa3.Muscularis4.Adventitia
8 1. Mucosa 2. Submucosa 3. Muscularis 4. Adventitia A photomicrograph of a histological section of the stomach
1. MucosaItis the innermost layerIt is most important andcomplicatedEmbodiesthe variousfunctions of different tractsegments?Can be subdivided intothree layers:a.Epitheliumb.Lamina propriac.Muscularis mucosa
9 1. Mucosa v It is the innermost layer v It is most important and complicated. v Embodies the various functions of different tract segments. v Can be subdivided into three layers: a. Epithelium b. Lamina propria c. Muscularis mucosa abc
1.Mucosaa.Epitheliumtwo types a barrier between the lumen ofthe digestive tract and the body* two types:stratifiedsquamousepi--on both ends:oral cavity,esophagus,and anal canal--withstandingabrasion(protection)·simplecolumnarepi.-on most parts:stomach,small andlargeintestine--absorptionandsecretion
1. Mucosa a. Epithelium —two types v a barrier between the lumen of the digestive tract and the body. v two types: stratified squamous epi. -on both ends: oral cavity, esophagus, and anal canal -withstanding abrasion (protection) simple columnar epi. -on most parts: stomach, small and large intestine -absorption and secretion