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13 Cards in this Set
- Front
- Back
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when talking about simple diffusion, what factors are important? what equation should we think of?
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Flux = Area X (concentration difference/distance).
So, increasing area or concentration difference increases flux. As would decreasing the area it goes over. |
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What is diffusion equation for membranes?
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J = Kb (Co-Ci)
Kb is the permeability constant for a solute, related to the Dm/membrane thickness, times B (a constant). |
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What factors of a solute affect its ability to cross a membrane?
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Lipid content and size - more lipid = easier, larger = harder. Also, charge can play a role.
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Osmosis involves the transport of what?
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Water - from areas of high water chemical activity (lots of water molecules without solutes interferring with water/water interaction) to areas of lower water activity (areas with lots of solutes getting in the way.)
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What two factors affect water movement?
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osmotic pressure and hydrostatic pressure.
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What is the equation for osmotic pressure, and what factors affect it?
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Pi = RT(Phi X I X C)
Phi is the osmotic coefficient, i is the disolution charge, and c is the concentration. |
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What is the equation for effective osmolarity?
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(phi) (I) (c)
osmotic coefficient, breakup ions, and concentration of solute. |
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How do the osmotic pressures of NaCl and glucose compare to one another? How abour CaCl2?
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a 1M solution of NaCl will exert twice as much osmotic force as that of glucose, due to the breakup I factor.
CaCl2 would exert an osmotic force 3X that of simple glucose. Same reason. |
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What 2 criteria must be met to have the transport of water due to osmolarity?
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permeable to water
impermeable to solutes (or at least reduced permeability). |
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Conceptually, what are the differences between osmolarity and tonicity?
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osmolarity is an inherent property of any solution in a container. it depends on the total number of particles.
tonicity depends on effective osmolarity - permeability matters. Changes in tonicity always change cell volume. |
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What's a quick way of figuring out the osmolarity of a solution?
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take the molarity and multiply it by the number of particles it disassociates into.
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If a solution is totally membrane impermeable, what's the relationship between tonicity and osmolarity?
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they're the same.
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what happens if a membrane IS solute permeable?
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the solution will always be HYPOTONIC, meaning the cells will explode.
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