5.7. Acid/Base Balance - Generation of Bicarbonate Flashcards
Where does the generation of bicarbonate occur?
Primarily in the distal tubule
What, in relation to generation of bicarbonate, becomes concentrated in the distal tubule?
Phosphate ions (which are not absorbed by the proximal tubule)
Why do phosphate ions become concentrated in the distal tubule?
Due to the removal of 95% of the initial filtrate
What is the process of generation of bicarbonate dependent on?
The CO2 entering the tubule cells, from the blood
What happens to the CO2, which enters the tubule cells (from the blood)?
This combines, with intracellular H2O, to form Carbonic Acid (H2CO3)
What happens to the newly formed Carbonic Acid (H2CO3) in the tubule luminal cells?
It splits to form:
1. Bicarbonate (HCO3-)
2. H+ ions
within the tubule cells
What happens to the newly formed Bicarbonate (HCO3-), within the Tubule Luminal Cells?
It is secreted into the peritubular capillaries
What happens to the newly formed H+ ions, within the Tubule Luminal Cells?
It is secreted into the Lumen
Other than the secreted H+ions, what else is present in the lumen?
Na2HPO4
What happens to the Na2HPO4 ?
One Na+ is reabsorbed, in exchange for a H+ ion
What happens to this monobasic phosphate?
It removes the H+ ion from the body
What happens to the Na+ ion formed as a result of the H+ ion taking its place?
It is passes into the Tubule Luminal Cell, and then into the Peritubular Capillary
