Renal Control Of Acid Base Disturbances

Question 1

What are the volatile sources (CO2 derived) of metabolic acids?

Answer 1

Glucose + O2 —> H+ and HCO3-
Fat + O2 —> H+ and HCO3-
Eliminated via the lungs

Question 2

What are the non-volatile (fixed) metabolic acid sources?

Answer 2

Glucose —> H+ and lactate (anaerobic)
Cysteine + O2 —> H+ and sulfate
Phosphoprotein + O2 —> H+ and phosphate
Eliminated via the kidneys

Question 3

What are the body’s buffer systems?

Answer 3

Bicarbonate, Hb, phosphate, and plasma proteins

Question 4

If acidemia is present what will the ICF take in?

Answer 4

H+ which will be buffered by raising ECF [K+]

Question 5

If alkalemia is present the ICF will donate what?

Answer 5

H+ which will be buffers by lowering ECF [K+]

Question 6

What is the Henderson-Hasselbach equation?

Answer 6

ph = 6.1 + log([HCO3]/[H2CO3])

H2CO3 can be determined by 0.03xPCO2

Question 7

Describe the renal reabsorption of bicarbonate

Answer 7

Mostly reabsorbed in the PT
1 mEq/L excreted per day
Very minuscule clearance value (bc most of it is reabsorbed)

Question 8

How is “new” bicarbonate generated?

Answer 8

During the process of urinary acidification when secreted H+ is buffered by NH3 —> NH4, phosphate, etc, for excretion while bicarbonate is reabsorbed

Question 9

What is net acid excretion (NAE)?

Answer 9

(UNH4 x V) + (UTA x V) - (UHCO3 x V)

Question 10

What must NAE equal each day in order to maintain acid base balance?

Answer 10

Must equal nonvolatile acid production

Question 11

What are titratable acids (TA)?

Answer 11

Salts of primarily phosphate but other constituents of urine such as creatinine do contribute
Accounts for 1/3 of NAE

Question 12

What is responsible for 2/3 NAE?

Answer 12

Ammonium (NH4) synthesis and secretion

Body can easily make as much as it needs unlike with TA