University:
Saint Louis University
Course:
PHYS 4110 | Intro to Biophysics
Academic year:

2021
Views:

152

Pages:

8
Author:

IKing

B/10 Diffusion and its significane in human body Diffusion spreading of particles of a substance due to thermal motion. broumion motion its the random uncorrelated motion of particles due to collisions with the surranding molecules. * in diffusion the parameters that determine the strength" of diffusion as follows: *flow density (flux) flow density of particles persecond. gives the amount of chemical material that passes through a unit area in unit time. its unit mol2. ms *Fick's first law The flow of particles per unit time across a unit area (flax) is proportional to the concentration drop. diffusion coefficient AR →concentration drop concentration gradien ficent (0) gives the amount of material diffused across • ina a time driven by a unit concentration drop. its unit depends on 1-size and the shape of the molecule- 2- interaction with the solvent 3-Viscosity of solvent. 4-temperature of the medium. in plot A and C the concentration differences (Cy-Co) are the same, but different distances. in plot Bandd c ore different across the concentration differences Same distances. •So, the A and C have identical concentration gradients, which drive the diffusion of the Same flax. Determination of the diffusion coefficient. we will apply Fick's second law to determine the diffusion coefficients of Ik and lila (Mnom) GAT the beginning of the experiment, the material is concentrated into a very small point In this case, the concentration profile is rotationally Symmetric which means the distance (r) from the center is the only important spatial parameter. So to determine the D we have to take images from the colored spot and get the diameter of the color spot and plot it square-root of elapsed time. as a function of