PotassiumBalance andPotassium Imbalancet,ShiHeZiMedicalCollege,Pathophysiology Department,HUST
Potassium Balance and Potassium Imbalance Pathophysiology Department, ShiHeZi Medical College, HUST
IPart
Part Ⅰ
PotassiumBalanceI Content and Distribution ofPotassium in the BodyI Intake and Excretion of Potassium
Potassium Balance Ⅰ Content and Distribution of Potassium in the Body Ⅱ Intake and Excretion of Potassium
Dietary K intakeSerum[K+1round4.5mmol/L70~100mmol/dayECF2%ICFTotal bodyK+K content[K*]160mmol/LExcretion31~57mmol/Kg98%ofthetotalbodyweightbodypotassiumtrivial normallySkinColon10%Moreingested,moreexcretedKidneys>80%Lessingested,lessexcretedNotingested,excretiongoesonContent,distribution,intakeand excretionofK
Dietary K intake 70~100mmol/day ECF 2% Serum [K+ ] round 4.5mmol/L K+ Skin trivial normally Colon 10% Kidneys > 80% More ingested, more excreted Less ingested, less excreted Not ingested, excretion goes on Content, distribution, intake and excretion of K Excretion ICF [K+ ] 160mmol/L 98% of the total body potassium Total body K content 31~57mmol/Kg body weight
I Maintenance of Potassium Homeostasis-DistributionofK+ acrossthecellmembraneandRegulationof renalK+excretion
Ⅲ Maintenance of Potassium Homeostasis —Distribution of K+ across the cell membrane and Regulation of renal K+ excretion
Distribution of Potassium acrossthe Cell MembraneTheNa+/K+ATPasemembranepumpandpermeabilityof ionchannels
Distribution of Potassium across the Cell Membrane The Na+ /K+ATPase membrane pump and permeability of ion channels
InfluencingFactors1.Hormones insulin, glucagoncatecholamines,thyroid hormoneNa/KATPast2.Serum [Kt][K+]↑Catecholamine3.pHofECFandplasmaInsulinosmolalityH+4.Othersrate of cell breakdownhypoxia, hypothermia, exercise
1.Hormones — insulin, glucagon, catecholamines, thyroid hormone 2.Serum [K+ ] 3.pH of ECF and plasma osmolality 4.Others — rate of cell breakdown, hypoxia, hypothermia, exercise Influencing Factors [K+]↑ Na+ Na+ /K+ - ATPase K+ K+ H+ Catecholamine Insulin
Regulation of Renal Potassium ExcretionH20H20NaNa+AldosteroneBownan'sCIcapsuleProximalNat/K+ATPasetubuleDistaltubuleH+-K+ATPaseNa+/K+ATPase(Mtactivated)Glomerulus精#oolectingCapillaryTubuleLooplofLnThenephronandcollectingtubule
Regulation of Renal Potassium Excretion Filtration, reabsorption and secretion of potassium The nephron and collecting tubule ClNa+ /K+ATPase( Mg2+ activated) Na+ /K+ATPase H+ - K+ ATPase
Regulation of Renal Potassium Excretion*Filtration,reabsorptionandsecretionofpotassiumSecretionofpotassiuminthedistalandcollectingtubulesprincipal cells, with Na+/K+ATPasemembranepump, for secretionof Kt
Regulation of Renal Potassium Excretion Filtration, reabsorption and secretion of potassium Secretion of potassium in the distal and collecting tubules principal cells, with Na+ /K+ATPase membrane pump, for secretion of K+
lumenbloodNatNatCICIK+Principal CellCO2COHHCO3CICIK+CellIntercalated
lumen Principal Cell blood K+ Na+ Na+ K+ ClClK+ CO2 HCO3 - ClClH + K + CO2 Intercalated Cell