B800 201

pH and Metabolism 1. Explain why the massive amount of acid produced each day by ATP hydrolysis

(ATP4- + H2O ADP3- + Pi2- + H+) does not result in a significant decrease in bodypH.

2. Explain how normal catabolic pathways for carbohydrates, lipids and proteins cancause net production of acid.

3. Indicate the sources of fixed and volatile acids.

4. Explain why the catabolism of the sodium salt of a carboxylic acid (e.g. sodiumlactate) results in the net utilization of acid.

5. Indicate the role of carbonic anhydrase in the transport of CO2 in the blood.

6. Show that an increase in the partial pressure of CO2 would lower blood pH.

7. Give the mechanism that explains the effectiveness of the CO2 - bicarbonate system asa buffer at physiological pH.

8. Calculate the pH of blood at bicarbonate concentration of 24 mM and pCO2 of 40mm Hg.

9. Describe the mechanisms responsible for handling of fixed and volatile acids by thebody.

10. Explain the significance and reason for the anion gap.

11. Indicate why and how glutamine metabolism is altered in chronic acidosis.

Emery SteeleRespiratory quotient = CO2 produced/O2 consumedR.Q. = 19.4/22 = 0.88

R.Q. on glucose = 1.0 (6/6)R.Q. on fat = 0.7 (16/23)

Emery SteeleNeutral food stuffs = neutral waste products

Emery SteeleCarbohydrates areneutral

Emery SteeleCO2 is a volatile acid

Emery SteeleCarbonicAnhydrase

Emery Steele

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Emery SteelepH = 7.4

Emery SteelepH = pKa + log [Pi-2]/[Pi]

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Emery SteeleGlucose -> 2 lactate + 2H+

Emery SteeleDoesnt matter

Emery SteeleDoesnt Matter

Emery SteeleRenal threshold forlactate is 6.6mM but doesntexit with proton

Needs to be oxidized

Emery SteeleLac. + 2H+ +6O2 -> 6CO2 + 6H20

Emery SteeleSodium lactate can be used to raise pHas well as sodium bicarbonate

Emery Steele(Na+) - (Cl-) + (HCO3-) = 12 +/- 2

Emery SteeleLarger anion gap during lactic and keto acidosis

Emery Steelecysteine and methionine generate sulfuric acidaspartate and glutamate generate bicarbonateHistidine, Lysine, Arginine generates protons

Emery SteeleKidney has to make new bicarbonate

Emery Steelefiltrate

Emery SteeleBlood

Emery SteeleGlutamine metabolism generates new bicarbonatewhen it is completely oxidized