Chapter5DigestionandAbsorption

(消化與吸收)1Digestion(消化):Thebreak-downprocesswherebythestructurallycomplexfoodstuffsofthedietareconvertedintosmallerabsorbableunitsbytheenzymesproducedwithinthedigestivesystem(食物在消化道內被分解為小分子物質的過程)

Mechanicaldigestion(機械性消化)Chemicaldigestion(化學性消化)2

Absorption(吸收):Theprocessthatthesmallerabsorbableunitsofdigestiongetacrossthealimentarytractmucosaandcomeintobloodorlymph.(食物經消化后通過消化道粘膜進入血液或淋巴的過程)3Section1StructureofDigestiveTract

(消化管的結構)Intracellulardigestion(胞內消化)Extracellulardigestion(胞外消化)

41.HumanDigestiveTract(人的消化管)

粘膜層：上皮上皮下層粘膜肌層粘膜下層:C.T組織結構(Submucouslayer)環行肌胃部是三層

Smoothmuscle內斜,中環,外縱縱行肌漿膜:C.T

(Serousmembrane)

(Tissuestructure)(Mucouslayer)52.TheInnervationofDigestiveTract

(消化管的神經支配)

ExtrinsicNS&IntrinsicNS

CNS肌間N叢粘膜下N叢R平滑肌分泌細胞內分泌細胞交.副交N交.副交N局部6Sympatheticnerve(交感N):

Thesubdivisionoftheautonomicnervoussystemthatdominatesin“fight-or-flight”emergencyorstressfulsituationsandperparesthebodyforstrenuousphysicalactivity.(源自T5~T10&L1~L2在腹神經節和腸系膜上下N節換元)7交感NNE胃腸平滑肌血管平滑肌運動及分泌內在N元8副：延髓背核疑核

迷走N盆NS2-4運動及分泌內在N元胃腸平滑肌血管平滑肌9Myentericplexus(肌間N叢)Submucousplexus(粘膜下N叢)Intrinsicplexus(內在N叢)：

包括感覺、中間、運動神經元構成一個完整且相對獨立的整合系統胃腸運動及分泌10Section2TheMovementandRegulationofDigestiveTract

(消化管的運動及調節)

Themovementofdigestivetract(消化道的運動):

Mastication(咀嚼)Deglutition(吞咽) Gastrointestinalmovement(胃腸運動)11Reflex(反射):Anyresponsethatoccursautomaticallywithoutconsciouseffort.(在NS的參與下對刺激的規律性應答)

Reflexarc(反射弧):Thecomponentsofareflexarcincludeareceptor,afferentpathway,integratingcenter,efferentpathway,andeffector.(感受器傳入NN中樞傳出N效應器)121.Gastricmovement(胃的運動)(1)Receptiverelaxation(胃的容受性舒張)Definition:

foodstimulatethereceptorsinpharynxandesophagus,throughvagusnervearouserelaxationoffundusandbodyofstomachmuscle.(食物刺激咽、食管等處感受器經迷走神經反射性引起胃底、胃體肌舒張)

significance肽類纖維？13(2)Toniccontraction(緊張性收縮)(3)Peristalsis(蠕動)GastricBER(胃的基本電節律):Itstemsfromlongitudinalmuscleofgreatercurvature,3~5timesperminutes,amplitudeisabout5~15mv.(起源于胃大彎的縱行肌層，每分鐘3~5次，振幅約5~15mv)14

Function

ofperistalsis(蠕動)

：①Leadtoamplemixingofchymeanddigestivejuice,thisisfacilitatedforchemicaldigestion.使食糜與消化液充分混合，利于化學性消化②Millfood(mechanicaldigestion)磨碎食物(即機械性消化)③Pushchyme推進食糜152.GastricEmptyingandItsRegulation

(胃的排空及其控制)Definition:Theprocessthatfoodenterintoduodenumfromstomach.(食物由胃排入12指腸的過程)

(1)胃排空(gastricemptying)

16Emptyingvelocity(排空速度)：Sugar>protein>fat;Sparse,thin,isosmoticquick(稀、細、等滲──快)(反之則慢)17(2)Regulationofgastricemptying

(胃排空的調控)

Entogastricfactorsaccelerateemptying(胃內因素促進排空)：①Entogastricfood（Nr）(胃內食物)②Gastrin（Hr）(胃泌素)

18Factorsofduodenuminhibitemptying(12脂腸因素抑制排空)：

①Gastrointestinalreflex（Nr）(腸胃反射)②Enterogastrone（Hr）(腸抑胃素)19Emptyingprocess

(排空過程)：

Entogastricfood(胃內食物)

emptyingstopped(排空停止)motilityofthestomach(胃運動)↑

胃運動↓幽門括約肌舒張幽門括約肌收縮胃內壓>12指腸內壓N(腸胃反射)H(腸抑胃素)Nr.Hr排空腸內胃酸被中和食物被消化吸收203.Themovementsofsmallintestine

(小腸的運動)(1)Toniccontraction(緊張性收縮)

Functions：

①Maintainbasicpressure(維持基礎壓力)②Thebasisofmovements(是腸運動的基礎)③Fixandkeepshapeofsmallintestine(維持小腸的位置形狀)21(2)Segmentationcontraction

(分節運動)

22Functions：①Itcanleadtoamplemixingofchymeanddigestivejuice,thisisfacilitatedforchemicaldigestion.(使食糜與消化液充分混合，利于化學性消化)②Itcanaccelerateclosecontactofchymeandintestinalwall,thisisfacilitatedforabsorption.(使食糜與腸壁緊密接觸，利于吸收)23③Itcanpressintestinalwall,acceleratebloodandlymphcircumfluence.(擠壓腸壁而促進血液、淋巴回流)(3)Peristalsis(蠕動)Peristalsisfunction:

pushchyme(推進食糜)24(4)Largeintestinalmovementanddefecation

(大腸運動和排便)

①Themovement

formsoflargeintestine

(大腸運動形式)

1)袋狀往返運動2)分節或多袋推進運動3)Peristalsis(蠕動)(massperistalsis,集團蠕動)

25

Brainstem,cerebralcortex(腦干、大腦皮層)S2-S4直腸牽張R

盆N陰部腹肌膈肌糞糞降結腸乙狀結腸收內括約肌松馳②Defecationreflex(排便反射)外括約肌松馳26(5)Regulationofdigestivetract

(消化管運動的調節)①Electricalactivity(電活動)BERAP②Nervefactors(神經因素)

Sympatheticnerve(-)gastrointestinalmovement

交感N(-)胃腸運動

Vagusnerve(+)gastrointestinalmovement迷走N(+)胃腸運動27Intraparietalnerveplexus(壁內N叢):

Regulatinggastrointestinalmovement(調節胃腸運動)Cerebralcortex(大腦皮層):Interestforfoodeffectsdigestion.Psychogenicenterorrhea(對食物的好惡對消化的影響精神性腹瀉)283.Humoralfactors(體液因素):

Gastrointestinalhormone(主胃腸激素):

Motilin(胃動素)Gastrin(胃泌素)

抑胃肽NESecretin(促胰液素)movementmovement29Section3TheSecretionandRegulationofDigestiveJuice(消化液的分泌及調節)1.Thesecretionofsaliva(唾液的分泌)30(1)Thecharacters、componentsandfunctionsofsaliva(唾液性質與成分與作用)

Moisten,dissolvefood(濕潤、溶解食物)clean,protectmouthcavity(清潔、保護口腔)lubricate,hydrolyzeamylum,killbacteria

(潤滑水解淀粉殺菌)31(2)

Theregulationofsalivarysecretion(唾液分泌的調節)Doubleexcitationeffectofsympathesisnerveandparasympathesisnerve(交感與副交感雙重興奮作用)

Conditionedreflex(條件反射)\ Unconditionedreflex(非條件反射)322.Gastricsecretion(胃液的分泌)

(1)Characters,componentsandfunctions

ofgastricjuice(胃液的性質、成分和作用)

無色透明，pH0.9～1.533

①Pepsinogen(胃蛋白酶原)

–chiefcellsecretion

(主細胞分泌)

pepsin胃蛋白酶

HClprotein月示和胨+pH234

②MucusandHCO3-(粘液與碳酸氫鹽)胃粘液-碳酸氫鹽屏障表面上皮細胞粘液頸細胞賁門腺glycoprotein35

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

cell(鹽酸壁細胞分泌)Thefunctionsofhydrochloricacid

(鹽酸作用):37

1)ActivatepepsinogenandsupplysuitablePHtopepsin(激活胃蛋白酶原并給胃蛋白酶提供活動所需的酸性pH)2)Killbacteria(殺菌)3)Acceleratedenaturationofprotein,andfacilitatedtodigestion

(使蛋白質變性易于消化)384)Acceleratethesecretionofpancreaticjuice、bile、smallintestinaljuice.

(促進胰液、膽汁、小腸液分泌)5)Acceleratetheabsorptionofsmallintestinaltoironandcalcium.(促進小腸對鐵、鈣的吸收)39Function：1)ProtectB12doesn’thydrolyzedbydigestiveenzyme(保護B12不被消化酶水解)2)AcceleratetheabsorptionofileummucosatoB12.(促進B12經回腸粘膜吸收)④Intrinsicfactor(內因子)

40(2)Theregulationofgastricjuicesecretion

(胃液分泌的調節)Shamfeeding(假飼)

Fig5-1841①Gastricjuicesecretionofcephalicphase

(頭期胃液分泌)

Thefoodstimulatescephalicreceptorcausegastricjuicesecretion.(食物刺激頭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)(頭部R)(中樞)(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

胃底胃體機械刺激──→中樞──→胃腺分泌胃液↑食物胃幽門部機械刺激──→壁內神經叢胃幽門部化學刺激─→幽門部G細胞─→胃泌素↑

Characters:

Acidityisquitehigh,digestiveenzymeisweakerthancephalicphase.

(酸度高，消化力(酶)比頭期的弱)ⅩⅩ45③Gastricjuicesecretionofintestinalphase(腸期胃液分泌)

Thefoodstimulatesintestinecausethegastricsecretion

（食物刺激腸引起的胃液分泌）46

Smallintestine

(小腸)

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

(胃液分泌的抑制性調節)

1)HCl胃竇粘膜G細胞

mucosalDcellsomatostain↑

intestinalmucosaScell

secretin↑

duodenalampullabulbomycin

↑

胃泌胃(粘膜D細胞)(生長抑素)(腸粘膜S細胞)(促胰液素)(12指腸球部)(球抑胃素)482)

Fatsmallintestineenterogasterone

mucosa

(腸抑胃素)(小腸粘膜)

gastricjuice

(胃液)

gastricmovement

(胃運動)

493)Hypertonicsolutionsmallintestinemucosa

(高張溶液)(小腸粘膜)

osmoticpressureR↑inhibitiveH↑(小腸滲透壓R)(抑制性H)胃液504)PGEVagusnerve,gastrin(迷走N、胃泌素)gastricwallreleasePGE

(胃壁釋放PGE)

胃液515)Theeffectsofdifferentfoodongastricjuice

secretion(不同食物對胃液分泌的作用)Protein>sugar>fat(蛋白質>糖類>脂肪)Corn,sweetpotato,alcohol,coffee(玉米面,白薯,紅薯,酒精,咖啡)523.Thesecretionofpancreaticjuice

(胰液的分泌)

HCO3-H2OEnzymesSmallvesselcell(小導管細胞)Acinarcell(腺泡細胞)Pancreas(胰腺)53(1)Thecharacters、componentsandfunctions

ofpancreaticjuice

(胰液的性質成分和作用)

CharactersAchromiaandtasteless(無色無臭)pH7.8-8.454Componentsandfunctions

①Waterdilutefood(稀釋食物)55②Sodiumbicarbonate(碳酸氫鹽)

counteractacidandsupplysuitablepHforactivityofdigestiveenzymeinsmallintestine(中和胃酸并提供小腸內消化酶活動所需的最適pH)pH7-8HHCO3-+56Organiccomponents:digestiveenzymes

(有機成分主要是各種消化酶)：①Pancreaticamylase(胰淀粉酶)maltsugar,glucose

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

(脂肪酸、甘油一酯、甘油)輔脂酶脂肪58③

胰蛋白酶

(trypsin)糜蛋白酶

(chymotrypsin)

(多肽、AA)

腸致活蛋白質和胨酸Trypsinogen(胰蛋白酶原)Chymotrypsinogen(糜蛋白酶原)+月示59④Others

Carboxypeptidase

羧基肽酶

Deoxyribonuclease

(脫氧)核糖核酸酶

60(2)Theregulationofpancreaticjuice

(胰液分泌的調節)

NrEnzymeisquiteabundant,H2OandHCO3-arefew.

(酶很豐富，但H2O、HCO3-很少)Hr①Secretin(促胰液素)

Enzymeisquitefew,H2OandHCO3-areabundant.(H2O、HCO3-很豐富，但酶很少)61②Cholecystokinin(膽囊收縮素)

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

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

Secretin(促胰液素)Food(刺激強度：鹽酸>蛋白分解產物>脂酸鈉)

smallintestinesecretin(促胰液素)↑mucosaScell(小腸粘膜S細胞)

水鹽胰腺小導管細胞

63

Cholecystokinin,CCK(膽囊收縮素)Food(蛋白分解產物>脂酸鈉>鹽酸>脂肪)smallintestineCCK↑mucosaIcell(小腸粘膜I細胞)cholecystcontractionpancreaticacinarcell

排膽汁酶(膽囊收縮)

(胰腺腺泡細胞)644.TheSecretionandRegulationofOtherDigestiveJuice(其它消化液的分泌及調節)Bile(膽汁):

VagusN(迷走N)G.,S.,CCK(+)Smallintestinaljuice(小腸液):

VagusNG.,S.,CCK,VIP65

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

intesti