医学类教学课件：尿的生成和排出.ppt

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1、尿的生成和排出第一节肾的功能解剖第二节肾脏功能的研究方法第三节肾小球的滤过功能第四节肾小管和集合管的物质转运功能第五节尿液的稀释和浓缩第六节尿生成的调节第七节尿的排放ReabsorptionandSecretionbytheRenalTubulesReabsorptionandSecretionbytheRenalTubules转运：重吸收(reabsorption):肾小管和集合管上皮将小管液中的水分和各种溶质重新转运回血液原尿:180L/天，终尿1.5L／天，>99％重吸收分泌(secretion)：血液中

2、的某些溶质被转运入小管液ReabsorptionandSecretionbytheRenalTubulesReabsorptionandSecretionbytheRenalTubulesMechanismsoftubulartransport1)PassivetransportSimplediffusionosmosisfacilitateddiffusionsalventdrag:thesolutesdissovedinthewaterarealsocarriedalongwiththewater.Mech

3、anismsoftubulartransport2)ActivetransportPrimaryactivetransportagainstanelectrochemicalgradientdirectlyrequiresmetabolicenergy(i.e.hydrolysisofATP)Examples:Na+-K+ATPase,H+ATPase,H+-K+ATPaseCa+2ATPaseReabsorptionandSecretionbytheRenalTubulesSecondaryactivetra

4、nsportTwoormoresubstancesinteractwithonespecificcarrierinthecellmembraneandaretranslocatedacrossthemembraneSymport(Co-transport)TransportedsubstancesmoveinthesamedirectionacrossthemembraneAntiport(Counter-transport)Transportedsubstancesmoveinoppositedirectio

5、nsacrossthemembraneReapportionandSecretionbytheRenalTubulesThepathwayofreabsorption1)Paracellulartransport5-10%ofwatertransferPassivediffusiononlyRequiresfavorableelectrochemicalgradientPassivediffusionofionsandlargenon-polarsolutes2)Transcellularpathway90-9

6、5%ofwatertransferPassivetransportAllactivetransport（三）物质通过肾小管上皮转运的途径顶端膜侧膜基底侧膜跨细胞转运途径细胞旁转运途径ReabsorptionandSecretionbytheRenalTubules3)PinocytosisUptakebycellsofparticlestoolargetodiffusethroughthecellmembraneExample:Reabsorptionoffilteredproteinsintheproxima

7、ltubulesReabsorptionbytheRenalTubules(一)Na+、Cl-Reabsorption1.近球小管中的重吸收70％(1)Na+和Cl-的重吸收前半段：主动(跨细胞)机制Na+与G、AA、HCO3－同向转运Na+-H+逆向转运前半段：主动(跨细胞)机制Na+与G、AA、HCO3－同向转运Na+-H+逆向转运后半段：主动(跨细胞)及被动(细胞旁)重吸收Na+与Cl-同向转运，Na+-H+／HCO3－逆向转运(2)水的重吸收：被动重吸收渗透跨细胞细胞旁水通道：水孔蛋白(a

8、quaporin)(AQP-1)Cl-HCO3-Cl-K+H2OH2O(一)Na+、Cl-和水的重吸收2.髓襻升支粗段对Na+、Cl-的重吸收：Na+：2Cl-：K+同向转运模式Na+-H+逆向转运Na+、Cl-、K+：一半跨细胞转运一半细胞旁转运水的重吸收：降支细段，渗透方式（15%）升支，不被重吸收氯化钠在髓襻升支粗段中重吸收的机制2、髓襻临床髓襻利尿剂：速尿、利尿酸钠抑制同向转