消化与吸收DigestionandAbsorption-浙江大学课件

消化与吸收

DigestionandAbsorption夏强，PhD浙江大学医学院生理学系电话：88206417,88208252Email：xiaqiang@两个概念消化——是指食物中所含的营养物质在消化道内被分解为可吸收的小分子物质的过程机械性消化化学性消化吸收——食物经消化后形成的小分子物质，以及维生素、无机盐和水通过消化道黏膜上皮细胞进入血液和淋巴的过程消化系统消化道消化腺消化系统的功能运动Movement分泌Secretion消化Digestion吸收Absorption排出EliminationStructureofthealimentarycanalNormalBERfrequenciesinthegastrointestinalsystem基本电节律basicelectricalrhythm:BER两套神经系统肠（内在）神经系统Entericnervoussystem(intrinsic)自主（外来）神经系统Autonomicnervoussystem(extrinsic)胃肠激素

Gastrointestinalhormones消化道内所含的内分泌细胞数远大于体内所有内分泌腺所含的细胞总数消化道是目前所知的体内最大的内分泌器官Gastrointestinalhormones，Guthormones口腔内消化咀嚼和吞咽

MasticationandswallowingTheswallowingreflexiscoordinatedbythemedullaoblongata,whichstimulatestheappropriatesequenceofcontractionandrelaxationintheparticipatingskeletalmuscle,sphincters,andsmoothmusclegroups.Thecoordinatedsequenceofcontractionandrelaxationintheupperesophagealsphincter,theesophagus,andtheloweresophagealsphincterisnecessarytodeliverswallowedfoodtothestomach.胃内消化胃的主要功能：暂时储存食物消化食物少量吸收胃液Gastricjuice成分HCl胃蛋白酶原Pepsinogen黏液Mucus碳酸氢盐HCO3-内因子IntrinsicfactorpH0.9-1.5黏液-碳酸氢盐屏障Mucus-HCO3-barrier幽门螺旋杆菌(HelicobacterPylori)胰液分泌

Pancreaticsecretion胰液pH7.8~8.4~1500ml/dayIsosmoticComponents:Pancreaticdigestiveenzymes:secretedbypancreaticaciniSodiumbicarbonate:secretedbysmallductulesandlargerductsSecretionofpancreaticdigestiveenzymesCarbohydrates--PancreaticamylasePancreaticlipaseFatCholesterolesterasePhospholipaseTrypsinogenProteinsChymotrypsinogenProcarboxypolypeptidaseProelastase急性胰腺炎

Acutepancreatitis胆汁分泌

Secretionofbilebytheliver胆汁的成分HCO3-

BilesaltsPhospholipidsCholesterolBilepigments…胆汁的功能：EmulsifyingordetergentfunctionofbilesaltsBilesaltshelpintheabsorptionof:FattyacidMonoglyceridesCholesterolOtherlipidsBigDropletsofFatSmallDropletsofFatMicellesFattyAcidsandMonoglyceridesChylomicronAssemblyDistributionandProcessingPreventingthecholesterolprecipitation&gallstones大肠的功能吸收水分和无机盐吸收微生物合成的维生素B复合物和维生素K完成对食物残渣的加工，形成并暂时储存粪便Inthelargeintestine,activetransportofsodium,coupledwithosmoticabsorptionofwater,aretheprimaryactivities.

MicrobeshereareactiveintheproductionofvitaminK.排便反射Defecationreflex体温

BodyTemperature体温恒温动物保持正常的体温是机体进行新陈代谢和生命活动的必要条件核心温度Coretemperature表层温度ShelltemperatureNormalcoretemperatureSiteMeanvalueoftemperatureStandarddeviationRangeofvariationoftemperatureAxillary36.79oC0.35736.0-37.4oCOral37.19oC0.24936.7-37.7oCRectal37.47oC0.25136.9-37.9oCThecircadian(“aboutaday”)rhythmofbodytemperaturepersistsevenamongpatientsinacoma;inadditiontothisbasicrhythm,fevers,exercise,andotheractivitiescanalterthebodytemperature.Bodytemperatureisacontrolledvariablethatissubjecttohomeostaticregulation.Thiscartoonindicatessomeofthewaysthatenvironmentalfactorscanincreaseordecreasebodytemperature.体温调节

自主性体温调节Autonomicthermoregulation行为性体温调节Behavioralthermoregulation体温中枢——主要在下丘脑Hypothalamus肾脏生理学

RenalPhysiology肾脏的功能调节水和电解质平衡，调节体液渗透压调节酸碱平衡排出机体代谢终产物及进入体内的过剩物质和异物糖异生内分泌：促红细胞生成素（erythropoeitin）肾素（renin）1,25-二羟胆骨化醇（1,25-OH2-D3）其他：激肽，前列腺素（PGE2,PGI2）尿生成的三个基本过程滤过Filtration重吸收Reabsorption分泌SecretionSubstanceXisfilteredandsecretedbutnotreabsorbed.SubstanceYisfilteredandsomeofitisreabsorbed.SubstanceZisfilteredandcompletelyreabsorbed.CompositionintheFiltrationFluidStructureoftheFiltrationMembrane葡萄糖的重吸收正常情况下，全部重吸收小管葡萄糖最大转运率Tm-G:Tubulartransportmaximumforglucose肾糖阈RenalthresholdforglucoseCriticalvalueoftheplasmaglucoseconcentrationwhenthekidneybeginstoexcreteglucose160-180mg/dL尿量正常：1000-2000ml/24hr多尿Polyuria：>2500ml/24hr少尿Oliguria：<400ml/24hr，或<17ml/hr无尿Anuria：<100ml/24hr，或12hr完全无尿抗利尿激素

Antidiuretichormone(ADH)又称血管升压素Vasopressin下丘脑合成垂体后叶释放作用：促进远曲小管和集合管对水的通透性收缩血管Actionofantidiuretichormoneonaquaporin(AQP)transport.AC,adenylatecyclase;AP1,transcriptionfactor;AVP,argininevasopressin;cAMP,cyclicadenosinemonophosphate;CRE,cAMPresponseelement;CREB-P,CREbindingprotein;EP3,prostaglandinreceptor;PGE2,prostaglandinE2.(FromBrownD,NielsenS:Thecellbiologyofvasopressinaction.InBrennerBM[ed]:BrennerandRector‘sTheKidney,7thed.Philadelphia,WBSaunders,2004,p574.)水利尿Waterdiuresis尿崩症DiabetesinsipidusInakidney-failurepatientundergoingdialysis,thebloodisbrieflyremovedfromthebod