1. Physiology of Acid-Base Balance Under the guidance of : Dr. Sandeep Tandon Professor and Head of Dept. of Pedodontics Dr. Ambika S. Rathore Dr. Rinku Mathur Dr .Shantanu Jain Dr. Tripti Sharma Rai

3. Acid-Base Balance

4. ph Scale

5. Acidosis and Alkalosis

6. Compensatory Mechanisms

7. Disturbance in acid-base balance

8. Anion Gap

9. Factors affecting acid-base balance in children

12. extracellular

13. intracellularbuffers

14. The physiologic processes: the excretion of volatile acids by the lungsand fixed acids by the kidneys4

15. 5 ACID-BASE BALANCE

17. Hydrogen containing substances which dissociate in solution to release H+H+ H+ H+ H+

18. 7 ACIDS Physiologically important acids include: Carbonic acid (H2CO3) Phosphoric acid (H3PO4) Pyruvic acid (C3H4O3) Lactic acid (C3H6O3) Phosphoric acid Lactic acid Pyruvic acid Carbonic acid

19. 8 BASES

21. A proton (H+) acceptor

22. Molecules capable of accepting a hydrogen ion (OH-)H+ H+ H+ H+

23. 10 BASES Physiologically important bases include: Bicarbonate (HCO3- ) Biphosphate (HPO4-2 ) Biphosphate Bicarbonate

24. 11 pH SCALE

25. 12 pH SCALE pH refers to Potential Hydrogen Expresses hydrogen ion concentration in water solutions. Water ionizes to a limited extent to form equal amounts of H+ ions and OH- ions H2OH+ + OH- H+ion is an acid OH-ion is a base

28. 15 pH SCALE Ph of the ECF: 7.40 NORMAL ACIDOSIS ALKALOSIS DEATH DEATH 7.3 7.5 7.4 6.8 8.0 Venous Blood Arterial Blood

30. 17 ACIDOSIS / ALKALOSIS

32. 20 ACIDOSIS / ALKALOSIS pH changes have dramatic effects on normal cell function 1)Changes in excitability of nerve and muscle cells 2) Influences enzyme activity 3) Influences K+ levels

34. Can lead to loss of consciousness

35. pH increase (more basic) can cause over-excitability

38. Normally K+issecreted in muchgreater amountsthan H+K+ K+ K+ K+ K+ K+ Na+ Na+ Na+ Na+ Na+ Na+ H+ K+

40. This leaves less K+ than usual excreted.

41. The resultant K+ retention can affect cardiac function and other systems.K+ K+ K+ K+ K+ K+ K+ K+ Na+ Na+ Na+ Na+ Na+ Na+ H+ H+ H+ H+ H+ H+ H+

42. 25 SOURCE OF HYDROGEN ION CO2 + H2O H2CO3 H+ + HCO3- H+ H2CO3 HCO3-

46. Combination of weak acid and a base (unprotonated compound).

47. Three major chemical buffer systems

48. Bicarbonate system

49. Phosphate system

50. Protein system28

53. Hydrogen ions generated by metabolism or by ingestion react with bicarbonate base to form more carbonic acidH2CO3 HCO3-

55. Hydrogen ions that are lost (vomiting) causes carbonic acid to dissociate yielding replacement H+ and bicarbonateH2CO3 HCO3-

56. 32 BICARBONATE BUFFER SYSTEM H+ HCO3- H2CO3 H2O CO2 + + Addition of lactic acid Exercise Loss of HCl Vomiting

59. Phosphate concentrations are higher intracellular and within the kidney tubules.

61. 35 PROTEIN BUFFER SYSTEM Proteins are excellent buffers because they contain both acid and base groups that can give up or take up H+ Proteins are extremely abundant in the cell The more limited number of proteins in the plasma reinforce the bicarbonate system in the ECF

63. As hemoglobin releases O2 it gains a great affinity for H+H+ O2 O2 Hb O2 O2

64. 37 H+ generated at the tissue level from the dissociation of H2CO3 produced by the addition of CO2 Bound H+ to Hb(Hemoglobin) does not contribute to the acidity of blood H+ O2 O2 Hb O2 O2

65. 38 As H+Hb picks up O2 from the lungs the Hb which has a higher affinity for O2 releases H+ and picks up O2 Liberated H+ from H2O combines with HCO3- HCO3-H2CO3CO2(exhaled) O2 O2 H+ Hb O2 O2

66. 39 RESPIRATORY CENTRE Pons Respiratory centers Medulla oblongata

68. Increases in CO2 and H+ stimulate the respiratory center

69. The effect is to raiserespiration rates

70. But the effectdiminishes in1 - 2 minutesCO2 CO2 CO2 CO2 CO2 CO2 CO2 CO2 CO2

71. 41 cell production of CO2 increases CO2 + H2O H2CO3 H2CO3 H+ + HCO3- H+ acidosis; pH drops H+ stimulates respiratory center in medulla oblongata rate and depth of breathing increase CO2 eliminated in lungs pH rises toward normal RESPIRATORY CONTROL OF pH

72. 42 RENAL RESPONSE The kidney compensates for Acid - Base imbalance within 24 hours and is responsible for long term control The kidney in response: To Acidosis Retains bicarbonate ions and eliminates hydrogen ions To Alkalosis Eliminates bicarbonate ions and retains hydrogen ions

73. 43 H+ K+ cell H+ K+ cell ELECTROLYTE SHIFTS Acidosis Compensatory Response Result - H+ buffered intracellularly - Hyperkalemia -Diabetic ketoacidosis Alkalosis Result Compensatory Response - Tendency to correct alkalosis - Hypo kalemia

75. Respiratory Acidosis

76. Respiratory Alkalosis

77. Metabolic Acidosis

79. 46 RESPIRATORY ACIDOSIS Caused by hyperkapnia due to hypoventilation Characterized by a pH decrease and an increase in CO2 pH CO2 CO2 CO2 CO2 CO2 CO2 CO2 CO2 CO2 CO2 CO2 pH CO2 CO2

85. kidneys eliminate H+ ion in acidic urineacidic urine

88. pH of blood is above 7.47.4 7.4 = = : 0.5 20

90. Leads to eliminating excessive amounts of CO2

91. Increased loss of CO2 from the lungs at a rate faster than it is produced

92. Decrease in H+CO2 CO2 CO2 CO2 CO2 CO2 CO2 CO2 CO2 CO2 CO2 CO2

93. 55 RESPIRATORY ALKALOSIS Can be the result of: 1) Anxiety, emotional disturbances 2) Respiratory center lesions 3) Fever 4) Salicylate poisoning (overdose) 5) Assisted respiration 6) High altitude (low PO2)

95. Retaining hydrogen ions

96. Increasing bicarbonate excretionHCO3- HCO3- H+ H+ HCO3- HCO3- H+ H+ H+ HCO3- H+ HCO3- HCO3- H+ H+ HCO3- HCO3- H+ H+ HCO3- H+

98. Decrease in blood pH and bicarbonate level

100. Accumulation of non-carbonic plasma acids uses HCO3- as a buffer for the additional H+ thus reducing HCO3- levelsMuscle Cell Lactic Acid HCO3-

104. Control diabetes with insulin or treat poisoning by removing the toxic substancefrom the blood

109. Increase in pH which has a non-respiratory origin7.4

112. 68 METABOLIC ALKALOSIS Gastric juices contain large amounts of HCl During HCl secretion, bicarbonate is added to the plasma H+ K+ HCl HCO3- Cl-

113. 69 METABOLIC ALKALOSIS The bicarbonate is neutralized as HCl is reabsorbed by the plasma from the digestive tract K+ HCl H+ Cl- H2CO3 HCO3-

115. Loss of HCl increases the plasma bicarbonate and thus results in an increase in pH of the bloodK+ HCl Bicarbonate not neutralized HCO3-

117. kidneys conserve H+ ions and eliminate HCO3- in alkaline urine

119. CLINICAL EVALUATION OF DISTURBANCES IN ACID BASE STATUS 74

120. ANION GAP The term anion gap (AG) represents the concentration of all the unmeasured anions in the plasma. The negatively charged proteins account for about 10% of plasma anions. Reference range is 8 to 16 mmol/l. 75 Anion gap = [Na+] - [Cl-] - [HCO3-] AG = [Na+] + [K+] - [Cl-] - [HCO3-]

124. lower capacity to reabsorb HCO3-

125. Very low birth weight babies: bicarbonate levels of 12-16 mmoles/l

126. Term babies : levels of 20-22 mmol/l.77

127. 78 The rate of metabolism in infants is twice as great in relation to body mass as in adults Twice as much acid is formed which leads to a tendency toward acidosis Functional development of kidneys is not complete until the end of the first month Renal regulation of acid base may not be optimal.

129. Preterm babies less capacity than a term neonate to buffer an acid load. 79

130. 80 Other Factors Growth results in deposition of base in new bone as the calcium salts in bone are alkaline salts. On a weight basis, fixed acid production is higher than in adults. Neonates and children < 12 months fixed acid production is 2 to 3 mmol/kg/day).

132. organic acidosis (enzyme defect resulting in accumulation of acidic metabolic intermediates)

133. lactic acidosis

134. hyperchloraemic acidosis

135. Feeding difficulties often in association with tachypnoea81

137. fructose-1,6-diphosphatase deficiency

138. pyruvatedehydrogenase deficiency. not an isolated finding as these children have serious dysfunctions of organ systemsesp. affecting brain, liver and muscle. 82

139. Other Acid-Base Disorders in Children Insulin dependent diabetes mellitus usually presents during childhood or adolesence. Poisoning in children may cause an acid-base disorder 83

140. REFERENCES Fundamentals of physiology: a human perspective:Lauralee Sherwood; Fluid and acid base balance; page:453-61 Essentials of medical physiology: K Sembulingam; Acid base balance:36-47 Ganong’s Review of Medical Physiology: Renal physiology: 679-682 84

141. THANK YOU Presented by: Dr. Ruby Kharkwal 1st year postgraduate student Department of Pedodontics 85