低钾血症的学习教案.pptxVIP

低钾血症的学习教案第1页/共19页 K+ Balance DiagramLungsIntercellularIntracellularKidneysLost in urinePlasmaNormal Values:Major Functions:MouthStomachSmall IntestineLargeIntestineLost in FecesIngestedLost in sweatK+3.5-5.0 mEq/LMaintains intracellular osmolarity, controls resting potential of nerve and muscle, exchanged for H+ to correct pH, exchanged for Na+ when distal tubules reabsorb Na+ Passive diffusionActive transportFiltered into glomerulus,depending on blood pressureand GFRSecreted by aldosterone-controlled Na+/K+ ATPasein distal tubuleNa+/K+ ATPase activated by insulin, epinephrine; inhibitedby digitalis, beta blockersPassive diffusionK+/H+ exchangeRepolarization(exercise, seizures)Reabsorbed in proximal tubule and loop of HenleK+/H+ exchange第2页/共19页 K+ 3.5-5.5 mEq/L, Total: 60 mEqK+ channelNa+K+K+Na+Na-K ATPaseNa-K ATPase+++++++_ _ _ _ _ _ _ K+Distribution of potassium K+ 150 mEq/L, Total: 4000 mEq第3页/共19页 1、Factors that modify transcellular K+ distribution（钾的肾外调节）Modifying factorsAcid-base status Blood PH( Acidosis/alkalosis ) Plasma HCO3- ( Low/high )Pancreatic hormone Insulin/GlucagonCatecholamine ?-adrenergic/ ?-adrenergicAlkalosisGlucagonAcidosisa-adrenergicInsulinb-adrenergicCELL K+第4页/共19页 Potassium Homeostasis第5页/共19页 2、肾脏的调节血钾在肾小球自由滤过约50-55%在近端肾小管重吸收约30-35%在髓袢重吸收远端小管和集合管泌钾第6页/共19页 Renal Handling of K+ in PCTK+(Paracellular route)K+Cl-X-第7页/共19页 Reabsorption of Sodium Chloride — Lessons from the Chloride Channels, NEJM,2004,350(13):1282Renal Handling of K+ in TALCaSR第8页/共19页 K reabsorption byH-K exchanger in intercalated cellsK secretion by Na-K exchanger in Principal cellsRenal Handling of K+ in DCT and CT第9页/共19页 二、引起低钾血症的原因 Insufficient potassium intake: Deficient dietary intakeTranscellular shift of K (no depletion): Hypokalaemic periodic paralysis Thyrotoxic periodic paralysis Barium poisoning Alkalosis Insulin excess第10页/共19页 Potassium depletion: Extra-renal losses: (1) Diarrhea (2) Rectal villous adenoma (3