EC lecture 3 pre reading PDF

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pre reading from lectures 3 of the human phys course...

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osmosis    

Most abundant substance to diffuse across the membrane is water Water that diffuses I and out is usually equal, so volume stays constant Requires a semi-permeable membrane Osmotic pressure – the pressure needed to stop the influx of water into the solution o This depends on the number of particles rather than the type

Osmol, osmolarity, osmolality    

Osmol – unit number of solute particles in solution that cause osmosis Particles that cause osmosis are called osmotically active particles Osmolality = # of osmol/Kg of water Osmolarity = # of osmol/L of solution

Tonicity: isotonic, hypotonic, hypertonic    

Normal osmolality is 300 osmoles per Kg of water Isotonic - same concentration as the cell Hypotonic – a solution that has a lower concentration than the cell (osmosis into the cell) cells swell Hypertonic – solution with a higher concentration than the cell. causes osmosis out of the cell. Cell shrinks...