pH

pH

1. Acid Substance releases H+

2. Bases Substance that accepts H+

3. Best indicator of acid/base status

   • Body goal-maintain acid/base homeostasis
     • Slight H+ change= Profound effect of body
       • Actual H+= .00000004 mEq/L

4. pH of blood= acid base status and balance

   • Balance between lungs and kidneys
     • Ratio of bicarbonate to carbonic acid 20:1

5. Range 0-14

   • water 7.0
     • measured in blood plasma
       • 7.32 In ICF more acidic
         • Range compatible with life 6.8-7.8
           • Variances can alter enzyme activity----nerve--tissue--cardiac fx

6. Relationship between pH and H+

   • Inverse
     • Logarithmic
       • pH meter measures H+ acitvity not concentration
         • Most free H+ are not really free but combined with H2O to form hydronium ions

7. Acidemia Range

   • Mild 7.35-7.30
     • Moderate 7.30 -7.20
       • Severe <7.20
   • Alkalemia
     • Mild 7.45-7.50
       • Moderate 7.50-7.55
         • Severe >7.55

8. Acid Homeostasis

   • Acid Excretion
     • Acid Buffering
       • Lungs 13000mEq/L pr day
         • Carbonic acid is removed as CO2
           • Lungs remove Volatile Acids
             • Co2 produced in healthy cells is converted to H2CO2 in the blood and then converted back to CO2 in the venous blood
       • Minimizes pH changes by soaking up acid and neutralizing bases
         • Good buffer is made of conjugate buffer pair
           • covert strong acids into weak acids or strong bases into weak bases. minimize pH changes but do not prevent them
             • 2 types= bicarbonate and nonbicarbonate systems
               • Bicarbonate System
                 • Strong acid- buffer paid change into weak acid and salt
                   • Strong Base- buffer pair will change into a weak base and water
                     • H2CO3/NaHCO3
               • NonBicarbonate Sytem
                 • IHOP
                   • Inorganic Phosphates Hemoglobin Organic Phosphates plasma protein
     • Kidneys
       • 50mEq/L pr day in urine
         • Removal of fixed acids-those that cannot be convverted to fas
           • Some fixed acids are part of normal metabolism