0x62448568…9229sent to0x8011df58…516c·#24,269,642·view on Etherscan
Osmosis breaks down and produces water on opposite sides of a membrane through which only electrons and protons pass, and it requires external dioxide (O2) in the compartment water moves to - the endosmotic compartment. The mechanism behind this is that adsorbed water also auto-ionizes (just like liquid water), and the conjugate ions as charge carriers are asymmetrical in their mobility, the hydroxide ion (OH-) is immobilized within the adsorbate while the hydrogen ion (H+) is free to move, and thus the hydrogen ions diffuse out of the adsorbate in all direction, in equilibrium with the attractive force back towards the then negatively charged adsorbate. When there is an asymmetry in the amount of adsorbate on either side a membrane that is permeable to protons and electrons only and that water can adsorb onto (i.e., an osmotic membrane), more H+ will diffuse from the side with more adsorbate (the exosmotic side , the side water moves from). The loss of cations (positive charge) will favour hydroxide ions breaking down into dioxide, water and electrons. The electrons will pass the osmotic membrane, and combine with H+ and dioxide to form water (and this is why osmosis requires external dioxide in the endosmotic compartment). Osmosis is thus an electro-chemical system, that generates an electric current.
The cell membrane is how the cell tames the electro-chemical system of osmosis so that the electrical current can be harnessed. The cell uses an electrical insulator rather than an osmotic (i.e., permeable to protons and electrons only) membrane, so that it can control exactly what path the electrons will take. It uses the electrons to power membrane proteins, and this is the purpose of the whole machinery: to provide electricity to membrane proteins so that they can do useful work. It then replaces the cation concentration gradient in osmosis (the hydrogen ions) with two other cations, such that it achieves a concentration gradient in both the forward and the backward direction. This lets the cell move electricity in both the forward and backward direction (the electrons follow the cation, which in osmosis is hydrogen ions), i.e., it can quickly recharge the system again after it has discharged it. It achieves this substitution by moving the H+ onto phosphate within the cell membrane (the phosphate heads of the phospholipid bilayer), and replacing the charge with Na+ on the outside of the cell and K+ on the inside of the cell, in equal proportions, charge-wise, to the phosphate heads. This architecture, besides letting the cell not just discharge but also recharge the adsorbed water outside the membrane, also lets the dioxide released during discharge of the anode move (by diffusion) directly to the cathode side - the phosphate heads on the inner leaflet where H+ is combining with O2 and electrons. The dixoide is released, and consumed, within the lipid bilayer itself, and the adsorbed water surrounding the cell membrane on both sides prevents the dixode from escaping. The architecture thus lets the O2 concentration available for the osmosis be higher than that of the surrounding bulk water or medium, and, it lets the cell make better use of the O2 it has - the same O2 released on one side can be directly used on the other (it thus has to some extent an infinite capacity, as long as the quantity of O2 is high enough to start the process).