ACID BASE BALANCE and Disorders

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ACID BASE BALANCE and Disorders
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Acids

• Are any substance which tends to release H in
  water , either by simple dissociation or reaction
• The strength of acids is measured by the extent
  to which it liberate H but not by the number of
  H in the acid molecule e.g. phosph . a. and
  carbonic a . are weaker than HCL ( the later is
  completely dissociated ).
• The acidity of the solution is determined by H-
  expressed in gm ion/l. ( or nmol/l.).

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Bases

• Are substances which tends to accept H, since
  the anion liberated along with H when acid
  dissociated were bases e.g. Cl in HCL, NH3 in
  NH4
• The strong base is that substance with high
  tendency to accept H e.g. anion of weakly
  dissociated acid e.g H2CO3

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Aprote

• Metallic cation e.g Na , K which are not bases
  or acids

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HYDROGEION HOMEOSTASIS

• The buffer
• It is the substance which resists change in its
  PH, when excess acid or base is added
• Usually are weak acids and its salts e.g. H2CO3

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• Addition of acids ? dissociation of the weak
  acid or its salt e.g. H2CO3 ( H , HCO3 0 slowely
  and the anion neutralize any excess acid ( H)
  e.g HCL NaHCO3 ? NACl H2CO3. ( weak acid is
  formed instead of strong one ).
• Addition of bases ? dissociation of the weak acid
  H HCO3 , H neutralize the base added without
  great change in PH.

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?pH?

• It is log10 Log10 of the
• reciprocal of (H)
• The Log10 of a number is the power to which 10
  must be raised to produce this number e.g log10
  102 if log10 to "x" number 7 so the number
  must be 107
• At pH6 (H) ??

1 H
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• pH Log10 Log10 (H) 6
• ( H) 10-6 0.000001 mol 1000nmol/L
• at pH7 , (H) will be 100 nmol/L so each one unit
  change in pH mean 10 folds change in (H)

1 H
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Blood Buffer systems

• Bicarbonate / Carbonic acid
• The most important buffer of plasma
• It presents in RBCs , but in lesser concentration

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HANDERSON HASSELBALCH equation
dissoeiation
hydration

• CO2 H2O H2CO3
• H HCO3
• K hydration
• H2CO3 ? H HCO3

H2CO3 CO2xH2O
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• K dissociation
• K combined x
• H2O is constant and so K ? K

H x HCO3 H2CO3
H2CO3 CO2xH2O
H xHCO3 H2CO3
H x HCO3 CO2xH2O
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• K
• ( H) K x
• pH Log10 Log log
  
• pK Log

H x HCO3 dCO2
dCO2 HCO3
1 (H)
1 K
HCO3 dCO2
HCO3 0.03xPCO2
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Note

• ( dissociation constant of CO2 0.03)
• ( PK. For BiC. / Carb. Buffer system 6.1)

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2) Phosphate buffer -

• Inorganic phosphate accounts for 5 of the
  nonbicarbonate buffer value, at a plasma Ph of
  7.4 , the ratio HPO4/H2PO4 is 80/20 ( 4/1)
  (PK6.8)

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• Organic phosphate in the RBCs in the form pf
  2.3-diphosphoglycerate accounts for 16 of the
  non bicarbonate buffer.
• H2PO4OH HPO4 H2O
• HpO4 H H2Po4

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Plasma protein buffer- 3)

• Albumin form 95 of the non bicarbonate buffer
  value of the plasma
• The most important buffer groups of proteins are
  the imidazole group of histidine ( 16 in each
  albumin molecule)

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Hemoglobin buffer

• Account for 84 of the RBCs non bic buffer the
  most important buffer groups are imidazole groups
  of Hb. Histidine

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• Carbamino Compoands
• Combination of small amount of CO2 in RBCs with
  Hb.R NH2 Co2 R NH COO H

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Regulation of (H)

• Dilution
• Buffer system ? Plasma
• HCO3/H2CO3 (201)
• B2HPO4 / BH2PO4 ( 41)
• Prot. /prot.H(95 of the non bic

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• RBCs
• HbO2 / HHb ( 84 of the non bicarb.)
• Carbamino compounds
• HCO3 /H2CO3 ( to less extent)
• 2.3 diph. glye.16of the non bic.

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• 3 . Respiratory Mechanism C.R.C. ( Central
  chem.., Periph. Chem.)
• 4 . Renal Mechanism
• Acid excrction
• Na -H exchange
• Ammonia formation and NH4 excretion
• H2PO4 excretion
• HCO3 reclamation