Describe the biochemical mechanism throgh which HCl is formed in the stomach(in humans) (?)

Jan 7, 2018

Here's my understanding of the mechanism.

Explanation:

Hydrochloric acid is produced by the parietal cells in the stomach.

These cells secrete about 60 mL $\text{HCl}$ per hour at a concentration of
roughly 0.16 mol/L.

This is about 3 × 10^6 times the concentration of $\text{H"^"+}$ ions in blood.

Thus, the secretion of hydrochloric acid depends on active transport.

The key player is a proton pump bb((1)" located in the cell membrane.

The dissociation of water within the cell generates $\text{H"^"+}$ and $\text{OH"^"-}$ ions.

The $\text{OH"^"-}$ ions combine with ${\text{CO}}_{2}$ to form $\text{HCO"_3^"-}$ and are transported out of the cell by anion exchange for $\text{Cl"^"-} \textcolor{w h i t e}{l} \boldsymbol{\left(2\right)}$ .

The $\text{Cl"^"-}$ ions are transported out of the cell by conductance channels $\boldsymbol{\left(3\right)}$.

The proton pump removes $\text{H"^"+}$ ions from the cell in exchange for $\text{K"^"+}$ ions. This effectively recycles the $\text{K"^"+}$ ions.

The net effect is that one $\text{H"^"+}$ ion and one $\text{Cl"^"-}$ ion leave the cell for each water molecule that dissociates.