胆汁酸代谢及其异常.ppt
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1、1,胆汁酸代谢及其异常Bile acid metabolism and its abnormity 一、胆汁的组成(composition of bile) 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。 Bile from the liver cells to bile acids, inorganic ions such as water and released into the tube formed by bile canaliculi .,2,bile pigment,cholesterol,inorganic salt,3,To promote digestion
2、and absorption of fat 促进脂肪的消化和吸收 To promote the absorption of fat-soluble vitamins 促进脂溶性维生素的吸收 Regulation of cholesterol metabolism, The maintenance of cholesterol in the bile of the state of dissolution 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 Functon of bile acid,4,Reduce oil/water surface tension 降低
3、油/水两相之间的界面张力 Make the hydrophobic lipids in aqueous micro-emulsion into a small micelle 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),5,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 Metabolism and function of bile acids (一)初级胆汁酸的生物合成 Biosynthesis of primarybile acid
4、s,概念(concept),胆固醇在肝细胞内转化生成的胆汁酸。Cholesterol in the liver cells generated into bile acids,6,胆酸 cholic acid,鹅脱氧胆酸 chenodeoxy cholic acid,游离型,甘氨胆酸 glycocholic acid,牛磺胆酸 taurocholic acid,甘氨鹅脱氧胆酸glycochenodeoxycholic acid,牛磺鹅脱氧胆酸taurochenodeoxycholic acid,结合型,7,8,部位(site):小肠(small intestine) 大肠(large inte
5、stine),(二)次级胆汁酸的生物合成Biosynthesis second bile acid,初级胆汁酸分泌到肠道后受肠道细菌作用生成的产物。 Primary bile acid secretion by the intestinal bacterial role in post-generated product,概念(concept):,9,10,11,12,13,14,胆汁酸本身的负反馈调节 Bile acid is a negative feedback regulation 甲状腺激素可促进胆汁酸合成 Thyroid hormone may promote bile acid
6、synthesis,(三)合成过程(synthesis process),关键酶:7-羟化酶(Hydroxylase),调节(regulation),15,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。 Bile acid synthesis by the liver cells, secreted into the bile into the intestine after most of the weight can be absorbed through the
7、 portal vein back to the cycle of the liver, liver cells from the intake, and the synthesis of new bile acid secretion with bile into the intestines - Between the liver and intestine bile acid cycle known as the bile acid enterohepatic circulation.,概念(concept),四.胆汁酸的肠肝循环 Enterohepatic circulation of
8、 bile acid,16,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。 Limited Bile acids play maximize the role of the emulsion; Bile acid / cholesterol ratio constant, Is not easy to form cholesterol gallstone.,胆汁酸的肠肝循环 Enterohepatic circulation of bile acid,意义(signification),17,18,第四节 肝病的生物化学代谢紊乱,一、肝硬化的临床生物化
9、学 Clinical biochemistry of hepatocirrhosis,肝硬化是一种以肝组织弥漫性纤维化、假小叶和再生结节形成为特征的慢性肝病。是许多肝脏疾病晚期的共同病变。临床上有多系统受累,以肝功能减损、门脉高压两大症侯群为主要表现,晚期常出现上消化道出血,肝性脑病,继发感染等严重的并发症。,概念(concept),Cirrhosis is a pathological diagnosis.It is characterized by widespread fibrosis with nodular regeneration. Its presence implies pre
10、vious or continuing hepatic cell damage.,19,注意:,肝小叶、血管结构改变,即假小叶形成。如小叶结构大部分完好(先天性肝纤维化)也不是肝硬化。,纤维化和结节再生必须同时存在。只有再生结节或纤维化不是肝硬化。(如肝门脉性硬化症没有结节再生),肝硬化的病变为弥漫性,累及整个肝脏。局部纤维化不是肝硬化。,20,常见的病因包括: 病毒性肝炎(viral hepatitis) 酒精性肝炎(alcoholic hepatitis) 胆汁郁积(cholestasis) 严重心力衰竭(severe heart failure) 肝豆状核变性(hepatolenticu
11、lar disease) -抗胰蛋白酶缺乏症(- antitrypsin deficiency),病 因 Aetiology,引起肝硬化的病因较多,同一病因可发展为不同病理类型的肝硬化,而同一病理类型的肝硬化亦可由不同病因引起。,21,1.肝硬化的生物化学机制 Cirrhosis of the biochemical mechanisms 缺氧和炎症刺激,导致胶原纤维合成增强。以I型及型为主。 Hypoxia and inflammatory stimulation, resulting in enhanced synthesis of collagen fibers. I type in t
12、he main-and . 机体免疫机能不足,肝细胞反复遭受HBV破坏,以及肝细胞结节状再生,纤维组织不断增生,导致肝硬化。 Lack of immune function, liver cells from recurring destruction of HBV, as well as nodular liver cell regeneration, continuous proliferation of fibrous tissue, leading to cirrhosis.,22,跟Kuffer细胞分泌多种细胞因子及胶原酶等生物活性物质以及储脂细胞产生胶原等有关。Kuffer cel
13、ls with a variety of cytokines and bio-active substances, such as collagenase, as well as fat-storing cells produce collagen and so on. 涉及许多遗传因素,这已成为肝细胞对损伤反应的独立病原因素。肝细胞和胆管上皮细胞内角蛋白的表达异常等都与肝纤维化有关。Many of the genetic factors involved, this has become a liver cell injury in response to the independent p
14、athogenic factors.,1.肝硬化的生物化学机制 Cirrhosis of the biochemical mechanisms,23,2. 肝硬化的生物化学诊断,1. 血清蛋白质检测 TP(总蛋白),ALB(白蛋白) ,A/G(白球比例),球蛋白 2.血清胆红素与胆汁酸-两者呈不同程度升高 3. 血清酶类-ALT,AST,MAO等增高 4. 凝血酶原时间延长,且VitK不能加以纠正,肝功能实验 Liver function test,24,分类(classification): 线粒体(Mitochondria) 向阳极移动 2种 结缔组织(Connective tissue)
15、 向阴极移动 2种,单胺氧化酶(monoamine oxidase,MAO),分布(distribution):肝、肾、脑,25,纤维化形成机制:,结缔组织中的MAO,如赖氨酰氧化酶催化胶原末端的部分羟赖氨酰基及赖氨酰基氧化成醛,然后与其临近的赖氨酰基生成Schiff碱。 这种稳定交联的形成使胶原纤维结构稳定,故血清中的MAO活性增高,常提示胶原纤维增生活跃。,26,-脯氨酸羟化酶测定( -proline hydroxylase, -PH),-PH催化胶原中脯氨酸变为羟脯氨酸,在胶原合成中起关键作用。 肝纤维化: -PH含量及活性,27,透明质酸( hyaluronic acid, HA)由间
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