胆汁酸代谢及其异常

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1、胆汁酸代谢及其异常Bileacidmetabolismanditsabnormity一、胆汁的组成(compositionofbile)胆汁是由肝细胞将胆汁酸、无机离子和水分等分泌到胆小管所形成。Bilefromthelivercellstobileacids,inorganicionssuchaswaterandreleasedintothetubeformedbybilecanaliculi.1bilepigmentcholesterolinorganicsalt2Topromotedigest

2、ionandabsorptionoffat促进脂肪的消化和吸收Topromotetheabsorptionoffat-solublevitamins促进脂溶性维生素的吸收Regulationofcholesterolmetabolism,Themaintenanceofcholesterolinthebileofthestateofdissolution调节胆固醇代谢,维持胆汁中胆固醇的溶解状态二、胆汁(主要是胆汁酸)的功能Functonofbileacid3Reduceoil/watersurfa

3、cetension降低油/水两相之间的界面张力Makethehydrophobiclipidsinaqueousmicro-emulsionintoasmallmicelle使疏水性的脂类在水相中乳化成细小的微团立体构象:亲水面-疏水面（较强的乳化剂）4原料(precursor)：胆固醇(cholesterol)部位(site)：肝细胞(liver)种类(type)：游离型、结合型三、胆汁酸的代谢与功能Metabolismandfunctionofbileacids（一）初级胆汁酸的生物合成Bios

4、ynthesisofprimarybileacids概念（concept)胆固醇在肝细胞内转化生成的胆汁酸。Cholesterolinthelivercellsgeneratedintobileacids5胆酸cholicacid鹅脱氧胆酸chenodeoxycholicacid游离型甘氨胆酸glycocholicacid牛磺胆酸taurocholicacid甘氨鹅脱氧胆酸glycochenodeoxycholicacid牛磺鹅脱氧胆酸taurochenodeoxycholicacid结合型67部位

5、(site):小肠(smallintestine)大肠(largeintestine)（二）次级胆汁酸的生物合成Biosynthesissecondbileacid初级胆汁酸分泌到肠道后受肠道细菌作用生成的产物。Primarybileacidsecretionbytheintestinalbacterialroleinpost-generatedproduct概念（concept)：8973127312771733122110111213胆汁酸本身的负反馈调节Bileacidisanegativef

6、eedbackregulation甲状腺激素可促进胆汁酸合成Thyroidhormonemaypromotebileacidsynthesis（三）合成过程(synthesisprocess)关键酶：7-α羟化酶(Hydroxylase)调节(regulation)14胆汁酸经肝细胞合成后，分泌入胆汁，进入肠道后大部分可被重吸收，经门脉循环回到肝脏，再由肝细胞摄取，与新合成的胆汁酸一同分泌入胆汁，肠-肝之间的胆汁酸循环称为胆汁酸的肠肝循环。Bileacidsynthesisbythelivercel

7、ls,secretedintothebileintotheintestineaftermostoftheweightcanbeabsorbedthroughtheportalveinbacktothecycleoftheliver,livercellsfromtheintake,andthesynthesisofnewbileacidsecretionwithbileintotheintestines--Betweentheliverandintestinebileacidcycleknownast

8、hebileacidenterohepaticcirculation.概念（concept)四.胆汁酸的肠肝循环Enterohepaticcirculationofbileacid15有限的胆汁酸发挥最大的乳化作用;并使胆汁中胆汁酸/胆固醇比例恒定,不易形成胆固醇结石。LimitedBileacidsplaymaximizetheroleoftheemulsion;Bileacid/cholesterolratioconstant,Isnoteasytoformcho