CORRECTLY
Metabolism & Acid-Base Balance
Carbon dioxide (CO2) is a byproduct of aerobic metabolism.
Carbonic anhydrase is the enzyme that converts CO2 to carbonic acid
(H2CO3).
Lactic acid is a byproduct of anaerobic metabolism of glucose.
Sulfuric acid is an end product of the oxidation of sulfur-containing amino
acids.
Phosphoric acid is an end product of the metabolism of phosphoproteins
and ribonucleotides used as an energy source.
Albumin binds with 40% of calcium in the blood.
The charge of albumin is negative.
In acidotic states, there is an increased amount of hydrogen ions (H+). This
causes albumin to bind more H+ ions and less calcium, leading to a higher
level of free calcium in the blood.
In alkalotic states, there is a decreased amount of hydrogen ions (H+). This
causes albumin to bind more calcium (due to H+ depletion), leading to a
decreased amount of free calcium in the blood.
When the extracellular fluid volume is expanded, it inhibits the reabsorption
of HCO3- in the proximal tubule.
A deficit in extracellular fluid volume results in an increase in the
reabsorption of HCO3-.
Extracellular fluid volume deficit stimulates the RAAS (Renin-
Angiotensin-Aldosterone System) hormone.
Angiotensin II stimulates the Na-H exchanger in the proximal tubule,
which increases HCO3- reabsorption.
Increased HCO3- reabsorption due to RAAS activation causes metabolic
alkalosis (contraction alkalosis), which can occur secondary to volume
depletion, such as with the use of loop/thiazide diuretics.
The renal excretion of hydrogen (H+) occurs in the distal tubule and
collecting ducts.
The two active transport systems used to secrete H+ are H-ATPase and H-
K-ATPase.
These systems move H+ into the lumen and move potassium (K+) from the
lumen into the cells.
Once in the lumen, H+ binds with monohydrogen phosphate (HPO42-).