BIO SCI E182 Lecture Notes - Extracellular Fluid, Molar Concentration, Tonicity
2 Mar 2014
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Document Summary
There is nothing pushing molecules down a concentration gradient---they are moving randomnly. Eventually, the concentration would have been about the same inside and outside the cell of. O2 and co2; concentrations would be homogeneous, delta c would be zero, no (0) net diffusion (although cards still moving) One chemical entity at a time when talking about diffusion. Diffusion can be considered between two planes, across one plane horizontally not vertically, or between two points. Rate of diffusion is directly proportional to: surface area: measured perpendicularly to rate of diffusion (so vertically, 1/thickness or 1/distance or inverserly proportional to thickness diffusion d, concentration difference (change =c2-c1, concentration gradient which is concentration difference/distance)---delta. C/distance; not the same as concentration difference; huge concentration differences across a distance. Membrane must be permeable to particular chemical species. Membranes are lipid bilayers with many inserted proteins. Inside of cell is chemically distinct from outside of the cell.
