Friday, October 07, 2005

Quiz 5 guide + general

Things to be expected:

from Excel
Atleast one question from this section. This will be to test how much you have learnt excel over the past 4 labs.

Membrane potential
What is a membrane potential, resting potential, action potential.
The Nernst equation
Nenrst potential for ions (both negative and positive)
Parallel conductance equation
What equations are used for single ions and multi ions
Under what circumstances your cell gets depolarized, hyperpolarized.
How will changes in concentrations Na, K and Cl, both intracellularly and extracellularly affect the membrane potential as well the latency and amplitude of the membrane potential?
How stimulus-response relationship (all-or-none response) works?

One question from upcoming lab of isometric muscle mechanics. It is going to be a long one so come prepared

General
Please donot forget to bring back TA review sheets. These will be helpful to me. Feel free to write what-so-ever is appropriate.

Also I will be giving mid term grades.

4 Comments:

Anonymous Anonymous said...

I have had difficulty explaining why changing Na+ concentration was so minor, whereas similar K+ changes had a significantly larger effect. Does it have something to do with the fact that they gave us a larger G for Na+ than that for K+?

5:46 PM  
Blogger Gaurav Joshi said...

This is because K+ is the major ion inside the cell (intracellular) whereas Na+ is mainly present towards the outerside of the cell. Since membrane potential is measured as the current that distributes from inner to outermembrane it is clear that change in concentration of ions inside the cell will ultimately effect membrane potential and this is why Na+ will have larger effect.

10:54 PM  
Anonymous Anonymous said...

So that means that Na+ is the ion responsible for the depolarization right?

11:29 PM  
Anonymous Anonymous said...

Matt - I think this is because in general the K+ concentration doesn't change much, as Gaurav said it is really the Na+ changes that make the difference since they are mainly located outside of the cell. When the K+ concentration is forced to change by a lot like we did in the lab, then you get a big difference in the potential but I don't think the concentration of K+ really changes that much in real life. I hope that helps.

6:47 PM  

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