# HW1 - say that “an ion satisfies the Nernst equation” 7...

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BIOE 398BS: Quantitative Human Systems Physiology Spring 2008 Bioengineering, University of Illinois at Urbana-Champaign 1 Problem Set 1. Due Friday, Jan. 25, 2008. 1. Define: osmosis, osmotic pressure, semipermeable membrane. Describe these in terms understandable to a high school student. 2. (a) Write the form of Fick’s first law of diffusion that describes diffusion of a substance across a membrane. (b) What is the meaning of the symbols in the equation? (c) State in words what the equation says. 3. What properties of a molecule and a plasma membrane affect the ability of the molecule to permeate the membrane? 4. Why is ion transport required for the regulation of cell volume? 5. Define an electrogenic membrane transport process. Is the Na+, K+, -ATPase an electrogenic ion pump? Why? 6. Write the Nernst equation and define the symbols in it. What does it imply when we
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Unformatted text preview: say that “an ion satisfies the Nernst equation”? 7. Chambers A and B are separated by a membrane. Chamber A contains 1 M KNO 3 . and chamber B contains 0.1 M KNO 3 . If K+ is in equilibrium across the membrane, what is the electrical potential difference, EA – EB? Which side is electrically positive? 8. In some ion channels, the conductance of the channel can be voltage sensitive. This will be explored further with the Hodgkin-Huxley model. Below, two types of voltage sensitive channels are shown in terms of conductance (in units of mho or Siemens, which is 1/resistance in ohms). Sketch the current-voltage (IV) curves for both ion channels if the reversal potential is -80 mV and +30 mV. Note that I should be on the y-axis and V on the x-axis. 1.0 0.75 0.5 0.25 0.0 -80 -40 0 40 80 g(V) V (mV) 1.0 0.75 0.5 0.25 0.0-80 -40 0 40 80 g(V) V (mV) A. B....
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