Harvard-MIT Division of Health Sciences and Technology HST410J: Projects in Microscale Engineering for the Life Sciences, Spring 2007 Course Directors: Prof. Dennis Freeman, Prof. Martha Gray, and Prof. Alexander Aranyosi HST.410J16.021 J Lecture 4 February 15, 2007 Dissolution Transport Transport Pumps and diffusion through Figure from Weiss, T. F. Cellular Biophysics, through water lipid bilayer channels Vol. I. Cambridge, MA: MIT Press, 1996. Intracellular Courtesy of MIT Press. Used with permission. Membrane AU Extracellular lipid bilayer I I Figure from Weiss, T. F. Cellular Biophysics, ""Ir Vol. I. Cambridge, MA: MIT Press, 1996. Courtesy of MIT Press. Used with permission. 0 0- 0.01 ~ , , , : , , , , 012345678 012345678 Time (h) Time (h)Vial 1 Vial 2 Vial 3 Vial 4 Vial N Cells loaded with solute n . 0. • . --" ,-Flow tube ,ItSolution free of solute n Sampling chambers uuuuu Figures from Weiss, T. F. Cellular Biophysics, Vol.I. Cambridge, MA: MIT Press, 1996. Courtesy of MIT Press. Used with permission. 0.05 1, 0 10 20 30 Time (ms)integralmembrane solute lipid protein \ f bilayer I membrane Figure from Weiss, T. F. Cellular Biophysics, Vol.I. Cambridge, MA: MIT Press, 1996. Courtesy of MIT Press. Used with permission. 0 0 30 60 90 120 Time (minutes) Image removed due to copyright restrictions. Illustration of a water channel in a cell membraneWater transport in digestive system Daily trafflc 800 g food + 1.2 L water ingested daily.1.5 L saliva 2 L gastric secretions.0.5 L bile I 7 L digestive fluids 1.5 L pancreatic secretions .1.5 L intestinal secretions Figure from Weiss, T. F. Cellular Biophysics, 15 pounds ofwater (10% of body weight) ancrear secreted and reabsorbed daily F'o'ol. I. Cambridge, MA: MIT Press, 1996. Courtesy of MIT Press. Used with permission. Osmosis Observations Henri Dutrochet(early 1800s).first described phenomenon and called it osmosis .developed first osmometer: animal bladder filled with test solution, plunge into water, swlls, turgid.pressure greater for solutions Vvlth more solute water Wllhelm Pfeffer (mid 1800s).osmosis can be stopped with hydraulic pressure.thistle tube + animal bladder (or artificial membrane by late 1800s) -water flows in direction to equalize sugar concentration -hydraulic pressure develops -flow stops vvtlen osmotic pressure = hydraulic pressure.pressure proportionalto concentration of solute.pressure increasesslightly Vvlth temperature Thistle 1 Water 1Henricus van't Hoff (1886) .formulated mathematical law .count number of particles in volumeV .measure temperatureT . osmotic pressure = pressure produced by gas with same number of particles, same volume, and same pressure van't Hoff's Law "/\-pressure concentration molar gar ' 8.314 Jl(mo1.K) .salts are different Svante Arrhenius (1 884) .PhD (age 25): dissolution of salts into ions .NaCl + Na+ + CI (;. conducts electricity) .count ions as separate particles + van' t Hoff s law works for salts as well osmdic pressure [Pa=Nlm2] -Arbacia eggs Figure from Weiss, T. F. Cellular Biophysics, Vol.I. Cambridge, MA: MIT Press, 1996. Courtesy of MIT Press. Used with permission. I I I ITune (minutes) Tune (minutes) Time (mrnutes) Figure from Weiss, T. F. Cellular Biophysics, Vol.I. Cambridge, MA: MIT Press, 1996. Courtesy of MIT Press. Used with