4)Acid Base Balance
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1 Acid-Base Balance Acid-Base Balance Dr. Suzanah Abdul Rahman Dr. Suzanah Abdul Rahman Kulliyyah of Allied Health Sciences Kulliyyah of Allied Health Sciences International Islamic University International Islamic University Malaysia Malaysia Kuantan Campus Kuantan Campus
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Transcript of 4)Acid Base Balance
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Acid-Base Balance
Dr. Suzanah Abdul Rahman
Kulliyyah of Allied Health Sciences
International Islamic University Malaysia
Kuantan Campus
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Acid-Base Balance
Acid-base balance depends on the level of H+ ionsNormal cellular function requires maintenance of pH of systemic arterial blood between 7.35 and 7.45Metabolic reactions produce excess H+ which can quickly rise to lethal levelsRemoval of H+ from body fluids and elimination through important processes*
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Acid-Base Balance
Major mechanisms
Buffer systemsExhalation of Carbon DioxideKidney excretion of H+*
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Buffer Systems
Systems include protein buffer system, carbonic acid-bicarbonate buffer system & phosphate buffer systemRapid removal of H+ through binding of excess highly reactive H+ from solutionpH is raised but H+ is not eliminated from the bodyCovert strong acids & bases into weak acids and bases*
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Protein Buffer System
Most abundant in intracellular fluid & blood plasmaBuffers both acids & basesImportant functional groups of protein are COOH & NH2 groupsCOOH releases H+ when pH risesNH2 combine with H+ when pH drops*
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Protein Buffer System
Protein hemoglobin important buffer of H+ in RBCs*
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Carbonic Acid- Bicarbonate Buffer System
HCO3- important in intracellular & extracellular fluidsKidney synthesize & also reabsorb filtered HCO3-Act as weak base to remove excess H+H2CO3 dissociates into H2O & CO2H2CO3 acts as a weak acid to provide H+ during shortageBuffer system cannot protect from pH changes when there is respiratory problems whereby there is shortage or excess of CO2*
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Phosphate Buffer System
Phosphate major anions in intracellular fluids but not in extracellular fluidsHence important system in cytosolDihydrogen phosphate as weak acid buffering strong base as OH-Monohydrogen phosphate as a weak base buffering H+ released by e.g. HClH+ that is part of H2PO4- passes into urine and excreted in maintenance of blood pH(weak base)
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Exhalation of Carbon Dioxide
Breathing helps maintain pH of body fluids!H2CO3 a volatile acid as it can be eliminated by exhalation of CO2Increased ventilation, increases CO2 exhalation decreasing H+ concentrationDoubled ventilation, pH 7.4 pH 7.63Ventilation reduced to one-quarter of normal, pH 7.4 pH 7.0pH & rate and depth of breathing operates via a negative feedback loop*
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Exhalation of
Carbon Dioxide*
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Kidney Excretion of H+
Metabolic reactions produce nonvolatile acids e.g. sulfuric acidRenal failure can cause build-up of non-volatile acids leading to deathSecretion of H+ at PCT and collecting ductsApical membrane of intercalated cells of collecting ducts have proton pumps that secrete H+ into tubular fluid Urine can be 1000 times more acidic than bloodSecreted H+ is buffered by ammonia to form ammonium ions and monohydrogen phosphate forming dihydrogen phosphateBoth ions cannot diffuse back into tubules cells hence they are excreted*
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Kidney Excretion of H+
Secretion of H+
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Kidney Excretion of H+
Buffering of H+ in urine
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Acid-Base Imbalances
Normal pH range btw 7.35 and 7.45Below 7.35 acidosis/ acidemiaMajor physio effects depression of synaptic transmission leading to disorientation, coma & deathHigher than 7.45 alkalosisMajor physio effects CNS and peripheral nerves overexcitability causing nervousness, spasms, convulsion & deathBoth conditions can be countered with compensation mechanisms either respiratory or renal*
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