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Unformatted text preview: Introduction to Biophysics Lecture 19 Osmotic Pressure Osmotic Flow Surface tension (force/length), [N/m] (note that the same as energy per area [N*m/m 2 or J/m 2 ] Note that tot stretch membrane to greater area we must do work ) dS = (4 R 2 ) = *4 *2RdR= 8 RdR pdV=p((4/3) R 3 ) = p4 R 2 dR 8 RdR = p4 R 2 dR = Rp/2 Laplaces formula For cell R=10 m, = 105 [m]*300[Pa]/2 = 1.5*103 [N/m] Depletion Interaction or Molecular Crowding R depletion zone (reduces the volume available to the particles, thus, its minimization increases the entropy) The depletion interaction is a short range. 1998, American Chemical Society. Used by permission. Osmotic flow is quantitatively related to forced permeation p eq = ck B T The pressure drop if system is brought to equilibrium. When p p eq Qflow rate to create a uniform pressure drop per unit length of p/L Q = R 4 p/8L  HagenPoiseuille relation ( R 4 /8L = 1/Z hydrodynamic resistance) Summary:...
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This note was uploaded on 12/09/2011 for the course PHYS 570 taught by Professor Staff during the Fall '08 term at Purdue UniversityWest Lafayette.
 Fall '08
 Staff
 Energy, Force, Work

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