泌尿系统教学课件：Chapter 4 酸碱平衡.ppt

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,Chapter 4,Acid-base balance and,acid-base disorders,internal environment homeostasis,Water balance,homeostasis,acid-base balance,electrolyte balance,1.,Acid-Base Balance,Acid-base Biochemistry,Regulation of pH,Laboratory Tests,2.Simple Acid-base DisordersMetabolic Acidosis,Respiratory Acidosis,Metabolic Alkalosis,Respiratory Alkalosis,3.Mixed Acid-base Disturbance,Contents,Part I:,Acid-base balance and its regulation,The basic meaning of acid-base balance is the stable H+in the body fluid.,I,、,Concept of acid and base,acid,：,An acid is a H,+,donor,when it is dissolved in water.After the loss of H,+,it becomes a base.,HA(acid),H,+,+A,(base),H2CO3,H,+,+HCO3,H,2,SO,4,H,3,PO,4,base,：,A base is a H,+,acceptor,when it is dissolved in water.After the combining of H,+,it becomes an acid,A(base),+,H,+,HA(acid),HCO3,+H,+,H2CO3,OH,-,HCO,3,-,SO,4,2-,HPO,4,2-,NH,3,(I),Source of acid,volatile acid,fixed acid,II,、,Sources of acid and base,The main origin of acid and base is the intracellular metabolism(catabolism of protein,carbohydrate and fat).,daily production,：,300-400L/d,Excretion:lung,1.volatile acid,H,2,CO,3,CO,2,H,2,O,H,2,CO,3,CA,metabolism of protein,carbohydrate and fat,H,+,+HCO,3,-,Reabsorption in kidney,RBC,、,kidney tubulesepithelium,、,alveolar epithelial cell,、,gastric mucosa,2.,unvolatile acid(fixed acid),：,(50-100mmol/d),Uric acid,phosphoric acid,(H3PO4)and,sulfuric acid,(H2SO4)are the products in the metabolic process of proteins and nuclear acids.,Lactic acid,and,ketonic bodies,(,-hydroxybutyric acid and acetoacetic acid,)can be formed from the metabolic process of carbohydrate and fat as intermediate products,when the oxygen supply is not sufficiency.,Exogenous acid(food and drug),：,Excretion through kidney,(II),Sources of base,Origin of bases,Endogenous,：,deamination,NH3,Less than acid production,Exogenous input,：,vegetables,and fruits,III,、,Regulation of acid-base balance,Henderson-Hasselbalch,Equation,Acid-base balance is mainly the balance between production and loss of acid and base.,pH=pKa+lg,HCO,3,H,2,CO,3,=pKa+lg,20,1,=6.1+1.3=7.4,H+,Buffer,Respiratory,Renal,ECF,ICF&bone,(Immediately)(24h)(13min)(hs;13d),Neutralize H,+,pa,CO,2,eH,+&,iK,+,exchange,Excrete H,+,Keep NaHCO,3,Acid-base balance,：,pH,HCO,3,/H,2,CO,3,or,pH,HCO,3,/PaCO,2,Source,Buffer system,Respiratory,Renal,Cellular,（,I,）,blood buffer system,表,1,全血五种缓冲系统 表,2,全血中各缓冲体系的含量与分布,缓冲酸 缓冲碱 缓冲体系 占全血缓冲体系,%,H,2,CO,3,HCO,3,+H,+,血浆,HCO,3,35,H,2,PO,4,-,HPO,4,2,+H,+,红细胞内,Hb 18,HPr Pr,+H,+,HbO,2,-,及,Hb,-,35,HHb Hb +H,+,磷酸盐,5,HHbO,2,HbO,2,+H,+,血浆蛋白,7,Buffer systems,：,consists of a weak acid and its salt,HCO,3,-,/H,2,CO3 is the most important buffer pair.Regulate CO,2,or HCO,3,-,through kidney and lung,，,the most important buffer pair,(,50%),。,fixed acid and base buffer system,HCO,3,-,/H,2,CO,3,buffer system,PH is dermatied by HCO,3,-,/,H,2,CO,3,。,character:,RBC,specificity,volatile acid buffer,CO,2,CA,：,carbonic anhydrase,CO,2,+H,2,O,CA,H,2,CO,3,CA,H,+,HCO,3,-,Cl,-,(RBC),HCO,3,-,Cl,-,HHO,2,HbO,2,-,HHb Hb,-,hemoglobin buffer system(,Hb,-,/HHb,、,HbO,2,-,/HHbO,2,),phosphate buffer system,HPO4,2-,/H,2,PO4,-,character:play a role in cell and kidney,protein buffer system,Pr,/HPr,Intracellular buffer,Mechanism of buffer,HCl+NaHCO,3,NaCl+H,2,CO,3,CO2,+H,2,O,NaOH+H,2,CO,3,NaHCO,3,+H,2,O,Accept H,+,or release H,+,，,decrease the change of pH,Character of,Buffer,Unvolatile acid,：,HCO,-,3,/H,2,CO,3,system,:,of the buffer capacity,Opened regulation:respiratory and renal,Volatile acid,：,Hb,-,/HHb,、,HbO,2,-,/HHbO,2,（,II,）,Mechanisms of respiratory control,change the depth or rate of respiration,change CO,2,elimination,HCO,3,-,/,PaCO2,Acid-base balance,1.,central chemoreceptor,PaCO2,(N:40mmHg),pH of,CSF,to,stimulate,central chemoreceptor,the respiratory center,Pulmonary ventilation volume,PaCO2 60mmHg(8kPa),Pulmonary ventilation volume,10,times,but,PaCO2 80mmHg(10.7kPa),inhibit respiratory center,，,named as,carbon dioxide narcosis,The central chemoreceptor is sensitive to the change of CO,2,which is easy to cross the blood-brain barrier.,It takes time for the H,+,to penetrate across the blood brain barrier into the interstitial fluid of the brain,the increase of H,+,in the brain is relatively slow,so the effect of H,+,on the central chemoreceptor will be slow.,central chemoreceptor,2.,peripheral chemoreceptor,PaO,2,、pH,、PaCO,2,to,stimulate,peripheral chemoreceptor,the respiratory center,Pulmonary ventilation volume,PaO,2,60mmHg(8kPa)the respiratory center；but PaO,2,30mmHg inhibit respirator center,。,Less sensitive than central chemoreceptor,3.Characteristic of respiratory compensation,(a)Timeliness.,The respiratory response begins within several minutes.,The respiratory response often takes 30 minutes,for the respiratory compensation.1224 hours to get maximal compensation.,（,b)limited compensation,(III)Renal regulation of acid-base Balance,Renal compensation begins from several hours after the addition of acid load,and it may take 35 days to reach the maximum of this compensatory capacity.,Kidneys play a major role in the regulation of pH in the body.,Excrete the nonvolatile acid,，,reabsorb the bicarbonate,，,“,排酸保碱,”,keep,HCO,3,-,maintain acid-base balance,。,HCO,3,-,filtrate through glomerulus freely,（,5000 mmol/d,），,85%90%is reabsorbed by proximal tubule,，,others are reabsorbed by distal convoluted tubule and collecting duct,，,0.1%is excretedurine pH 6.0,。,urine pH vary from 4.4 to 8.0,1.in proximal tubule,(,a)Na,+,-H,+,exchange,2.in distal tubule&collecting duct,-,intercalated cell,:secrete H,+,upper membrane:,(a)H,+,-ATPase;,(b)H,+,-K,+,ATPase,Urinary acidification,（,H,2,PO,4,-,NH,4,+,）,base membrane:,Cl,-/HCO,3,-,exchange,3.secretion of NH3/NH4,+,in proximal tubule,petitive inhibition between K,+,-Na,+,exchange and,H,+,-Na,+,in distal tubule,K+-Na+exchange:secrete K+,reabsorb Na+,，,H+-Na+exchange:secrete H+,reabsorb Na+,acidosis,，,H+-Na+exchange,K+-Na+exchange,hyperkalemia,。,（,IV)Cellular regulation,(a)H,+,-K,+,exchange,(b)Cl,-,-HCO,3,-,exchange,(c)Utilizing of bone salt,(,d)Synthesis of urea from NH,3,1.H,+,-K,+,exchange,When H,+,in ECF(serum)is increased,the H,+,will move into the cells,as a exchange for electrical neutrality,K,+,will shift from ICF to the ECF.So the pH of ECF(serum)will increase to normal,but hyperkalemia may occur.,2.Cl,-,-HCO3,-,exchange,When CO2 in ECF(serum)is increased,CO,2,will move into the cells,CO,2,combines H,2,O to form carbonic acid,then H,2,CO,3,dissociates to form H,+,and HCO,3,the HCO3,moves out of the RBC,for neutrality,Cl,moves into the cells.,3.Utilizing of bone salt,In chronic metabolic acidosis,bone salt,Ca,3,(PO4),2,is also utilized as a buffer base,but the expense is decalcification of bone and osteoporosis(loose and soft bone).,Ca3(PO4)2+4H,+,3 Ca,2+,+2 H2PO4,It is not a good way of regulating acid-base balance by utilization of bone salt4.Synthesis of urea from NH3 in liver cells,Source,Buffer system,Respiratory,Renal,Cellular,Part II,laboratory tests of acid-base,disturbances,1,.pH,pH is the negative logarithm(-log)of H,+,in a solution.H,+,=40nmol/L(pH=7.4),The normal range in artery blood=7.357.45(7.41),The survival range of pH6.87.8,According to the Henderson-Hasselbalch equation:,The pKa is the dissociation constant of carbonic acid(=6.1),24 HCO,3,metabolic factor,pH=6.1+log -,1.2 H,2,CO,3,respiratory factors,20,=6.1+log-=6.1+1.3=7.4,1,The pH is determined by the ratio of,HCO,3,20,-=-,H,2,CO,3,1,No matter how the absolute amounts of HCO,3,and H,2,CO,3,change,once the ratio remains 20/1,the pH would be 7.4(normal).,24 HCO3 metabolic factorpH=6.1+log -1.2 H,2,CO3,respiratory factors,The primary changes determines the nature of the acid-base imbalance.,The purpose of secondary change is to restore the pH.,According to the pH:,compensatory acid-base disturbances,decompensatory acid-base disturbances,Clinical significance of PH,(anticoagulant artery blood,insulation of air),A normal range of pH may represent three different situations:,acid-base balance;,compensatory acidosis or alkalosis;,a mixed decompensatory acidosis and decompensatory alkalosis.,Clinical significance,pH7.45 decompensatory alkalosis,(alkalemia),2,.PaCO2(partial pressure of carbon dioxide in arterial blood),CO,2,in blood:,(a)23%HbCO2 in RBC,(b)70%HCO3,-,in plasma,(c)7%CO,2,molecule in plasma,CO,2,is determined by the rate of CO2 production and the rate of CO,2,elimination.,PaCO2 is the tension of CO2 caused by CO2 molecule movement.,The normal range=3346(40)mmHg(4.396.25 kPa).,The capability of normal lung to eliminate CO2 is very good.CO2 retention will not occur with normal ventilation.Generally speaking,the PaCO2 is determined mainly by the respiration,so the PaCO2 is called the“,respiratory factor,”.,Higher PaCO2 is due to the inhibition of respiration.,Lower PaCO2 is due to overventilation.,PaCO2,Significance,PaCO246mmHg,Primary increase:respiratory acidosis,Secodary increase:metabolic alkalosis,(compensated by lung),PaCO2SB(CO2 retention),the reason must be the effect of respiratory factor,which indicates respiratory acidosis or metabolic alkalosis compensated by lung.,If AB value predicted:with respiratory acidosis,Value measured value predicted:with metabolic alkalosis,Value measured 80 mmHg,6.,treatment priciples,(a),Treat the primary diseases which cause respiratory acidosis.(antibiotic,antispastic drugs),(b)Improve properly the ventilation.,(c)Prevent from(respiratory alkalosis)over-ventilation during artificial respiration.,（,d)Be careful to alkaline drug(NaHCO,3,),THAM,III,、,Metabolic alkalosis,Characterized by a primarily elevation in plasma HCO,3,-,concentration and a high pH.,1.c,oncept,2.Classification,According to the therapeutic effect of 0.9%NaCl,(A)saline-responsive alkalosis,(B)saline-resistant alkalosis,3.Pathogenesis,(1),saline-responsive alkalosis,(a)Increased loss of H,+,(b)More administration of HCO3,or precursors of bicarbonate,(a)Increased loss of H,+,a)from stomach,There is a lot of H,+,in the gastric juice.Vomiting and gastric suction will lose H,+,HCO3,-,cl-is lost through gastric juice,hypochloremic alkalosis,HCO,3,-,is absorbed into blood in stomach,then to intestinal juice to neutralize,H,+,.,Hypokalemia alkalosis,Effective blood volumedecrease,secondary aldosterone increase,Some diuretics(e.g.furosemide,),can inhibit the reabsorption of Cl and Na,+,in loop,more Na,+,is reabsorpted with HCO3 (without Cl)in distal tubules;renal fluid folw rate increase,b)Increased loss H,+,from kidneys,(b)More administration of HCO3,or precursors of bicarbonate,a)Patients with gastric ulcer may be orally given excessive NaHCO,3,to neutralize gastric juice.,b)Sharp correction of acidosis by excessive alkali administration can lead to metabolic alkalosis.,c)Transfusion of anticoagulant blood with sodium citrate citrate.,.,(2)Chloride-resistant type,Primary hyperaldosteronism,Secondary hyperaldosteronism caused by:hypovolemia,Cushings syndrome,severe hypokalemia:Paradoxical acid urine,4.Compensation of metabolic alkalosis,The compensation of metabolic alkalosis is the opposite direction of the compensation in metabolic acidosis.,(1),Respiratory compensation,：,H,pulmonary ventilation volume,CO,2,elimination,PaCO,2,HCO,3,-,/H,2,CO,3,(quickly,limted),But 46PaCO2 value predicted:with respiratory acidosis,Value measured value predicted:with respiratory acidosis,Value measured value predicted:with metabolic alkalosis,Value measured value predicted:with metabolic alkalosis,Value measured value predicted:with metabolic acidosis,.,Maximal compensatory value up to:12 mmol/L,4.Changes of laboratory parameters(acute),pH P,a,CO,2,SB(,),AB BB(,),BE(,),HCO,3,-,secondary decrease,H,2,CO,3,primary decrease,increase,Changes of laboratory parameters(chronic),pH P,a,CO,2,SB,AB BB -BE,HCO,3,-,secondary decrease,H,2,CO,3,primary decrease,increase,5.,Effect of respiratory alkalosis,CNS,dysfunction,：GABA,，,cerebral blood flow,2.,increased neuromuscular excitability(hypocalcemia,),tingling,twitching,3.,hypokalemia,4.hypophosphatemia,6.,treatment priciples,Primary disease,Prevent mis-operation of mechanical ventilator,5,CO,2,mixtrue gas,inhalation,or mask,V.Mixed Acid-base Disturbances,Concept,Metabolic acidosis,metabolic alkalosis,respiratory acidosis and respiratory alkalosis are four types of simple acid-base disturbance when these disturbances occur separately.,A mixed acid-base disturbance is defined as the simultaneous co-existence of two or more simple disorders in the same patient.,Double acid-base disorders,Triple acid-base disorders,Any two or three simple acid-base disturbances can occur simultaneously in a patient except the respiratory acidosis and respiratory alkalosis,because one can never have hypoventilation and hyperventilation at the same time.,Mixed acid-base disturbances occur frequently as a part of severe underlying illness with a high mortality.,Mixed Acid-base Disturbances,Case discussion,A 45-year-old man had chronic cough for 20 years.He had a shortness of breath,orthopnea with edematous ankles for 1 month.The laboratory findings were:,pH=7.26 PaO2=55 mmHg,PaCO2=60 mmHg AB=22 mmol/L,Predicted:HCO3,-,=0.4x P,aCO2,3,HCO3,-,=24+0.4x 20,3=2935,Measured:22,pH reduced severely.,No respiratory compensation for M.acidosis,No renal compensation for R.acidosis,Respiratory acidosis+metabolic acidosis,