萝卜家园Chapter5DigestionandAbsorption消化与吸收

Chapter5DigestionandAbsorption

(消化与吸收)1Digestion(消化):Thebreak-downprocesswherebythestructurallycomplexfoodstuffsofthedietareconvertedintosmallerabsorbableunitsbytheenzymesproducedwithinthedigestivesystem(食物在消化道内被分解为小分子物质的过程)

Mechanicaldigestion(机械性消化)Chemicaldigestion(化学性消化)2

Absorption(吸收):Theprocessthatthesmallerabsorbableunitsofdigestiongetacrossthealimentarytractmucosaandcomeintobloodorlymph.(食物经消化后通过消化道粘膜进入血液或淋巴的过程)3Section1StructureofDigestiveTract

(消化管的结构)Intracellulardigestion(胞内消化)Extracellulardigestion(胞外消化)

41.HumanDigestiveTract(人的消化管)

粘膜层：上皮上皮下层粘膜肌层粘膜下层:C.T组织结构(Submucouslayer)环行肌胃部是三层

Smoothmuscle内斜,中环,外纵纵行肌浆膜:C.T

(Serousmembrane)

(Tissuestructure)(Mucouslayer)52.TheInnervationofDigestiveTract

(消化管的神经支配)

ExtrinsicNS&IntrinsicNS

CNS肌间N丛粘膜下N丛R平滑肌分泌细胞内分泌细胞交.副交N交.副交N局部6Sympatheticnerve(交感N):

Thesubdivisionoftheautonomicnervoussystemthatdominatesin“fight-or-flight”emergencyorstressfulsituationsandperparesthebodyforstrenuousphysicalactivity.(源自T5~T10&L1~L2在腹神经节和肠系膜上下N节换元)7交感NNE胃肠平滑肌血管平滑肌运动及分泌内在N元8副：延髓背核疑核

迷走N盆NS2-4运动及分泌内在N元胃肠平滑肌血管平滑肌9Myentericplexus(肌间N丛)Submucousplexus(粘膜下N丛)Intrinsicplexus(内在N丛)：

包括感觉、中间、运动神经元构成一个完整且相对独立的整合系统胃肠运动及分泌10Section2TheMovementandRegulationofDigestiveTract

(消化管的运动及调节)

Themovementofdigestivetract(消化道的运动):

Mastication(咀嚼)Deglutition(吞咽) Gastrointestinalmovement(胃肠运动)11Reflex(反射):Anyresponsethatoccursautomaticallywithoutconsciouseffort.(在NS的参与下对刺激的规律性应答)

Reflexarc(反射弧):Thecomponentsofareflexarcincludeareceptor,afferentpathway,integratingcenter,efferentpathway,andeffector.(感受器传入NN中枢传出N效应器)121.Gastricmovement(胃的运动)(1)Receptiverelaxation(胃的容受性舒张)Definition:

foodstimulatethereceptorsinpharynxandesophagus,throughvagusnervearouserelaxationoffundusandbodyofstomachmuscle.(食物刺激咽、食管等处感受器经迷走神经反射性引起胃底、胃体肌舒张)

significance肽类纤维？13(2)Toniccontraction(紧张性收缩)(3)Peristalsis(蠕动)GastricBER(胃的基本电节律):Itstemsfromlongitudinalmuscleofgreatercurvature,3~5timesperminutes,amplitudeisabout5~15mv.(起源于胃大弯的纵行肌层，每分钟3~5次，振幅约5~15mv)14

Function

ofperistalsis(蠕动)

：①Leadtoamplemixingofchymeanddigestivejuice,thisisfacilitatedforchemicaldigestion.使食糜与消化液充分混合，利于化学性消化②Millfood(mechanicaldigestion)磨碎食物(即机械性消化)③Pushchyme推进食糜152.GastricEmptyingandItsRegulation

(胃的排空及其控制)Definition:Theprocessthatfoodenterintoduodenumfromstomach.(食物由胃排入12指肠的过程)

(1)胃排空(gastricemptying)

16Emptyingvelocity(排空速度)：Sugar>protein>fat;Sparse,thin,isosmoticquick(稀、细、等渗──快)(反之则慢)17(2)Regulationofgastricemptying

(胃排空的调控)

Entogastricfactorsaccelerateemptying(胃内因素促进排空)：①Entogastricfood（Nr）(胃内食物)②Gastrin（Hr）(胃泌素)

18Factorsofduodenuminhibitemptying(12脂肠因素抑制排空)：

①Gastrointestinalreflex（Nr）(肠胃反射)②Enterogastrone（Hr）(肠抑胃素)19Emptyingprocess

(排空过程)：

Entogastricfood(胃内食物)

emptyingstopped(排空停止)motilityofthestomach(胃运动)↑

胃运动↓幽门括约肌舒张幽门括约肌收缩胃内压>12指肠内压N(肠胃反射)H(肠抑胃素)Nr.Hr排空肠内胃酸被中和食物被消化吸收203.Themovementsofsmallintestine

(小肠的运动)(1)Toniccontraction(紧张性收缩)

Functions：

①Maintainbasicpressure(维持基础压力)②Thebasisofmovements(是肠运动的基础)③Fixandkeepshapeofsmallintestine(维持小肠的位置形状)21(2)Segmentationcontraction

(分节运动)

22Functions：①Itcanleadtoamplemixingofchymeanddigestivejuice,thisisfacilitatedforchemicaldigestion.(使食糜与消化液充分混合，利于化学性消化)②Itcanaccelerateclosecontactofchymeandintestinalwall,thisisfacilitatedforabsorption.(使食糜与肠壁紧密接触，利于吸收)23③Itcanpressintestinalwall,acceleratebloodandlymphcircumfluence.(挤压肠壁而促进血液、淋巴回流)(3)Peristalsis(蠕动)Peristalsisfunction:

pushchyme(推进食糜)24(4)Largeintestinalmovementanddefecation

(大肠运动和排便)

①Themovement

formsoflargeintestine

(大肠运动形式)

1)袋状往返运动2)分节或多袋推进运动3)Peristalsis(蠕动)(massperistalsis,集团蠕动)

25

Brainstem,cerebralcortex(脑干、大脑皮层)S2-S4直肠牵张R

盆N阴部腹肌膈肌粪粪降结肠乙状结肠收内括约肌松驰②Defecationreflex(排便反射)外括约肌松驰26(5)Regulationofdigestivetract

(消化管运动的调节)①Electricalactivity(电活动)BERAP②Nervefactors(神经因素)

Sympatheticnerve(-)gastrointestinalmovement

交感N(-)胃肠运动

Vagusnerve(+)gastrointestinalmovement迷走N(+)胃肠运动27Intraparietalnerveplexus(壁内N丛):

Regulatinggastrointestinalmovement(调节胃肠运动)Cerebralcortex(大脑皮层):Interestforfoodeffectsdigestion.Psychogenicenterorrhea(对食物的好恶对消化的影响精神性腹泻)283.Humoralfactors(体液因素):

Gastrointestinalhormone(主胃肠激素):

Motilin(胃动素)Gastrin(胃泌素)

抑胃肽NESecretin(促胰液素)movementmovement29Section3TheSecretionandRegulationofDigestiveJuice(消化液的分泌及调节)1.Thesecretionofsaliva(唾液的分泌)30(1)Thecharacters、componentsandfunctionsofsaliva(唾液性质与成分与作用)

Moisten,dissolvefood(湿润、溶解食物)clean,protectmouthcavity(清洁、保护口腔)lubricate,hydrolyzeamylum,killbacteria

(润滑水解淀粉杀菌)31(2)

Theregulationofsalivarysecretion(唾液分泌的调节)Doubleexcitationeffectofsympathesisnerveandparasympathesisnerve(交感与副交感双重兴奋作用)

Conditionedreflex(条件反射)\ Unconditionedreflex(非条件反射)322.Gastricsecretion(胃液的分泌)

(1)Characters,componentsandfunctions

ofgastricjuice(胃液的性质、成分和作用)

无色透明，pH0.9～1.533

①Pepsinogen(胃蛋白酶原)

–chiefcellsecretion

(主细胞分泌)

pepsin胃蛋白酶

HClprotein月示和胨+pH234

②MucusandHCO3-(粘液与碳酸氢盐)胃粘液-碳酸氢盐屏障表面上皮细胞粘液颈细胞贲门腺glycoprotein35

Functions：Lubricate,protectgastricmucosa,gastricmucosalbarrier;recoveringgastricmucosalepithelia.(润滑、保护胃粘膜胃粘液屏障，胃粘膜屏障;胃粘膜上皮的更新)36③Thesecretionofhydrochloricacid-parietal

cell(盐酸壁细胞分泌)Thefunctionsofhydrochloricacid

(盐酸作用):37

1)ActivatepepsinogenandsupplysuitablePHtopepsin(激活胃蛋白酶原并给胃蛋白酶提供活动所需的酸性pH)2)Killbacteria(杀菌)3)Acceleratedenaturationofprotein,andfacilitatedtodigestion

(使蛋白质变性易于消化)384)Acceleratethesecretionofpancreaticjuice、bile、smallintestinaljuice.

(促进胰液、胆汁、小肠液分泌)5)Acceleratetheabsorptionofsmallintestinaltoironandcalcium.(促进小肠对铁、钙的吸收)39Function：1)ProtectB12doesn’thydrolyzedbydigestiveenzyme(保护B12不被消化酶水解)2)AcceleratetheabsorptionofileummucosatoB12.(促进B12经回肠粘膜吸收)④Intrinsicfactor(内因子)

40(2)Theregulationofgastricjuicesecretion

(胃液分泌的调节)Shamfeeding(假饲)

Fig5-1841①Gastricjuicesecretionofcephalicphase

(头期胃液分泌)

Thefoodstimulatescephalicreceptorcausegastricjuicesecretion.(食物刺激头部感受器引起的胃液分泌)42CephalicR

nervecentergastricglandsecretegastricjuice

Gcell----→gastrin（胃泌素）↑characters:

quantityandacidityishigh,digestiveenzymeishigher.(量、酸度很高，消化力(酶)尤高)(头部R)(中枢)(胃腺分泌胃液)43②Gastricjuicesecretionofgastricphase(胃期胃液分泌)

Foodstimulatesstomachcausethegastricjuicesecretion.

(食物刺激胃引起的胃液分泌）

44

胃底胃体机械刺激──→中枢──→胃腺分泌胃液↑食物胃幽门部机械刺激──→壁内神经丛胃幽门部化学刺激─→幽门部G细胞─→胃泌素↑

Characters:

Acidityisquitehigh,digestiveenzymeisweakerthancephalicphase.

(酸度高，消化力(酶)比头期的弱)ⅩⅩ45③Gastricjuicesecretionofintestinalphase(肠期胃液分泌)

Thefoodstimulatesintestinecausethegastricsecretion

（食物刺激肠引起的胃液分泌）46

Smallintestine

(小肠)

foodGastrin，entero-oxyntin（胃泌素、肠泌酸素)Gastricglandsecretegastricjuice(胃腺分泌胃液)characters:fewquantity.(量少)47④Inhibitoryregulationofgastricsecretion

(胃液分泌的抑制性调节)

1)HCl胃窦粘膜G细胞

mucosalDcellsomatostain↑

intestinalmucosaScell

secretin↑

duodenalampullabulbomycin

↑

胃泌胃(粘膜D细胞)(生长抑素)(肠粘膜S细胞)(促胰液素)(12指肠球部)(球抑胃素)482)

Fatsmallintestineenterogasterone

mucosa

(肠抑胃素)(小肠粘膜)

gastricjuice

(胃液)

gastricmovement

(胃运动)

493)Hypertonicsolutionsmallintestinemucosa

(高张溶液)(小肠粘膜)

osmoticpressureR↑inhibitiveH↑(小肠渗透压R)(抑制性H)胃液504)PGEVagusnerve,gastrin(迷走N、胃泌素)gastricwallreleasePGE

(胃壁释放PGE)

胃液515)Theeffectsofdifferentfoodongastricjuice

secretion(不同食物对胃液分泌的作用)Protein>sugar>fat(蛋白质>糖类>脂肪)Corn,sweetpotato,alcohol,coffee(玉米面,白薯,红薯,酒精,咖啡)523.Thesecretionofpancreaticjuice

(胰液的分泌)

HCO3-H2OEnzymesSmallvesselcell(小导管细胞)Acinarcell(腺泡细胞)Pancreas(胰腺)53(1)Thecharacters、componentsandfunctions

ofpancreaticjuice

(胰液的性质成分和作用)

CharactersAchromiaandtasteless(无色无臭)pH7.8-8.454Componentsandfunctions

①Waterdilutefood(稀释食物)55②Sodiumbicarbonate(碳酸氢盐)

counteractacidandsupplysuitablepHforactivityofdigestiveenzymeinsmallintestine(中和胃酸并提供小肠内消化酶活动所需的最适pH)pH7-8HHCO3-+56Organiccomponents:digestiveenzymes

(有机成分主要是各种消化酶)：①Pancreaticamylase(胰淀粉酶)maltsugar,glucose

(麦芽糖、葡萄糖)淀粉57②Lipase(胰脂肪酶)Fattyacid,glyceride,glycerin

(脂肪酸、甘油一酯、甘油)辅脂酶脂肪58③

胰蛋白酶

(trypsin)糜蛋白酶

(chymotrypsin)

(多肽、AA)

肠致活蛋白质和胨酸Trypsinogen(胰蛋白酶原)Chymotrypsinogen(糜蛋白酶原)+月示59④Others

Carboxypeptidase

羧基肽酶

Deoxyribonuclease

(脱氧)核糖核酸酶

60(2)Theregulationofpancreaticjuice

(胰液分泌的调节)

NrEnzymeisquiteabundant,H2OandHCO3­arefew.

(酶很丰富，但H2O、HCO3-很少)Hr①Secretin(促胰液素)

Enzymeisquitefew,H2OandHCO3­areabundant.(H2O、HCO3-很丰富，但酶很少)61②Cholecystokinin(胆囊收缩素)

Enzymeisabundant,quantityisslightlyincreased.(酶多，量增加少许)③Gastrin(胃泌素)

Enzymeisabundant,quantityisslightlyincreased.(酶多，量增加少许)62

Secretin(促胰液素)Food(刺激强度：盐酸>蛋白分解产物>脂酸钠)

smallintestinesecretin(促胰液素)↑mucosaScell(小肠粘膜S细胞)

水盐胰腺小导管细胞

63

Cholecystokinin,CCK(胆囊收缩素)Food(蛋白分解产物>脂酸钠>盐酸>脂肪)smallintestineCCK↑mucosaIcell(小肠粘膜I细胞)cholecystcontractionpancreaticacinarcell

排胆汁酶(胆囊收缩)

(胰腺腺泡细胞)644.TheSecretionandRegulationofOtherDigestiveJuice(其它消化液的分泌及调节)Bile(胆汁):

VagusN(迷走N)G.,S.,CCK(+)Smallintestinaljuice(小肠液):

VagusNG.,S.,CCK,VIP65

intestinalmucosa(肠粘膜)Chyme(食糜)localreflex(局部反射)

intesti