I Homeostasis a Concepts i pH potential power of Hydrogen ii Acid substance that donates a proton H ion iii Base substance that accepts a proton H ion iv Neutrality 7 35 7 45 1 Concentration of H ions in pure water with equal amounts 2 At equilibrium H2O OH H where H 1x 10 7 of hydroxyl ions moles L v Acidity high H concentration H 1x 10 7 moles L vi pH 7 1 7 35 vii Alkalinity low H concentration H 1x 10 7 moles L viii pH 7 7 45 14 b pH Regulation c Blood pH regulations has a very narrow range 7 35 7 45 1 15 x 10 7 d At extreme pH proteins and organs lose normal function pH 7 3 pH moles L 7 5 e Buffers i Pka acid dissociation constant ii Henderson Hasselbalch equation pH pKa log iii Buffer is most effective within 2 pH units of its pKa 1 Maximum buffering capacity when pKa pH 2 You want to equal amount of base and acid f Chemical buffers maintain neutrality i Substance that minimizes pH changes of a solution following the addition of small amounts of acid base ii HA weak acid A conjugate base of weak acid iii Equilibrium of weak acid in solution 1 HA H A iv K1 dissociation of HA into H ion and A v K2 dissociation of H and A into HA acid g Chemical buffers i After final equilibrium is achieved a small change in the concentration of one component will cause the equilibrium reaction to shift in an attempt to re establish the final proportion of components 1 2 If small amounts of HA are removed from the weak acid equilibrium reaction the reaction will shift to the left in order to restore the original conditions If small amounts of H or A are removed the reaction would shift to the right h Physiological buffers i Hemoglobin ii Bicarbonate iii Phosphate iv Proteins i Physiological acids i Body s metabolic pathways produce several acidic waste products ii 2 types of acidic waste 1 Volatile acid carbon dioxide 2 Fixed acids phosphates sulfates organic acids lactic acid acetoacetic acid beta hydroxybutyric acid ketoacids 3 Hypoventilation trapping CO2 in the body to increase acidity II Acid Base Regulation a Buffer systems regulate H ion concentration b Lungs and kidney maintain pH homeostasis c Bicarbonate Buffer System i Ratio between carbonic acid and bicarbonate is maintained by the lung CO2 H2CO3 H HCO3 ii Carbonic anyhdrase d Lungs e Kidneys i Too acidic hyperventilate ii Too alkaline hypoventilate i Hydrogen and bicarbonate carbonic acid dissociate H2 CO2 urine to Kidney Wall and form carbonic acid and dissociate Hydrogen to urine and bicarbonate to blood III Acid Base Disorders a Acidosis pH 7 35 b Alkalosis 7 45 c Check out the ABC sheet on webcourses d Metabolic Acidosis i Due to increased production of organic acids ii Decrease in normal 20 1 ratio of HCO3 iii Pathogenesis decreased bicarbonate increase carbonic acid H2CO3 Increase in acid 1 2 Excess base removal decrease 3 Combination of acid increase and base decrease iv Compensatory physiological response 1 Compensatory respiratory alkalosis via hyperventilation reduce PCO2 and partial increase in HCO3 H2CO3 ratio does not remove metabolic acids from body v Etiology 1 Uncontrolled diabetes excess fatty acid oxidation leads to accumulation of acetoacetic acid and hydroxybutyric acid 2 Fasting results in increased acetoacetic and hydroxybutyric 3 acid levels Increase in anaerobic metabolism increase lactic acid production 4 Local tissue hypoxia low tissue PO2 lactic acid production 5 Renal failure acidosis failure to exchange H ions for Na ions 6 Liver disease impairs urea and ammonia formation causing H ion retention vi Etiology 1 Medication salicylate intoxication converts to acid before 2 excretion Ingested poisons convert to acid metabolites methanol ethylene glycol paraldehyde ammonium chloride 3 Large quantities of isotonic sodium chloride infusion high Na competes with H ions for renal excretion 4 Ingestion of carbonic anhydrase inhibitors interferes with bicarbonate vii Clinical manifestations 5 Diarrhea and colitis decrease bicarbonate concentration 1 ABG below normal bicarbonate concentration 2 pH below normal if uncompensated 3 Headache abdominal pain 4 CNS depression confusion lethargy stupor coma 5 Ventricular dysrhythmias due to myocardial intracellular acidity 6 Decreased cardiac contractility 7 Brainstem dysfunction when pH 6 9 fatal a Cardiorespiratory arrest b MA caused by hyperventilation 1 Disorders that impair ability of lungs to expel carbon dioxide pulmonary edema bronchoconstriction pneumonia asthma apnea emphysema morphine injection barbiturate poisoning 2 Respiratory distress syndrome RDS common in premature infants who lack sufficient surfactant levels in their lungs gas exchange inhibited 3 Adult respiratory distress syndrome ARDS ii Clinical manifestations 1 Tachycardia cardiac dysrhythmias 2 Headache neurological abnormalities blurred vision tremors vertigo disorientation lethargy iii Physiological response e Respiratory Acidosis i Etiology 1 Increase renal acid excretion with Na and bicarbonate retention 2 Hyperventilation if possible iv Diagnosis 1 Increased carbon dioxide and slightly decreased bicarbonate concentration 2 Decreased HCO3 H2CO3 ratio f Metabolic Alkalosis i Etiology 1 Intake of bicarbonate baking soda powder and bicarbonate precursors acetate citrate lactate 2 Loss of chloride 3 Prolonged vomiting 4 Gastric fluid aspiration vomit still stays out of 5 bloodstream leads to loss of gastric HCl causing an increase in blood pH Impaired ability of kidney to regulate electrolyte balance corticosteroids hyperaldosteronism getting rid of aldosterone Cushing syndrome overproduces cortisol ii Clinical manifestations 1 Postural hypotension 2 Can associate hypokalemia bilateral muscle weakness 3 Increased neuromuscular excitability tingling in fingers and toes tetany signs that can progress to seizures 4 Altered mental state death if pH rises to 7 8 iii Compensatoy physiological response 1 Compensatoy respiratory acidosis via hypoventilation increases PCO2 and bicarbonate resulting in pH decrease Increase renal bicarbonate excretion if alkalosis persists 2 iv Diagnosis 1 High PCO2 2 High HCO3 H2CO3 ratio 3 Alkaline urine g Respiratory Alkalosis i Etiology 1 Hyperventilation a Hysteria b Excess crying c Pregnancy childbirth d Salicylate intoxication e Respiratory CNS impairment f Asthma g Fever h Pulmonary embolism i Excess mechanical respirator use j Hyperventilation ii Clinical manifestations mouth 1 Paresthesias tingling and numbness of fingers and around 2 Carpal and or pedal spasm 3 4