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Title: If they would move spontaneously in one direction, why don’t they quickly come to equilibrium, ... Post by: roxana90 on Sep 16, 2010 The cells of your body have Na+-K+-ATPases, which use energy from ATP to pump Na+ out of the cell and K+ into the cell. One result of this is that there is an electrochemical gradient of Na+ ions across the plasma membrane, with more Na+ outside than inside the cell.
-->given this gradient, in which direction will Na+ ions move spontaneously? -->if they would move spontaneously in one direction, why don’t they quickly come to equilibrium, with roughly equal concentration on each side of the plasma membrane? Title: If they would move spontaneously in one direction, why don’t they quickly come to equilibrium, ... Post by: bio_man on Sep 16, 2010 - Sodium will have a tendency to move inside the cell.
- Depends on the permeability of the membrane. Moreover, for every three sodiums that move out, 2 potassium ions move in, so it is impossible to accomplish equilibrium. You are using active diffusion which requires energy to go against the concentration gradient. http://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120068/bio03.swf::Sodium-Potassium%20Exchange%20Pump (http://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120068/bio03.swf::Sodium-Potassium%20Exchange%20Pump) http://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120107/bio_a.swf::Sodium-Potassium%20Exchange (http://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120107/bio_a.swf::Sodium-Potassium%20Exchange) |