Question about EPSP and IPSP

[mpelter]

Hi Everyone,

 

Someone today had sent me a question about IPSPs and EPSPs that I really liked.

 

"If the equilibrium potential for chloride is changed so that it is between the resting membrane potential and threshold potential, then will increasing the permeability of chloride in the postsynaptic potential trigger an EPSP or IPSP?"

 

This is a great way to study. To make sure that you truly understand the material, try changing it slightly (like here with the equilbrium potential) and explaining what  will happen. I'll post my answer later tonight. In the meantime, tell me what you think!

 

From the emails I've recieved, I feel that most of you are preparing well and are on the right track. If you have any point that is not clear, we are still available for questions. Don't hesitate to ask!

Good Luck!

Megan

 

[mpelter]

Oops! Posted it in wrong topic! Here we are:

Hi Everyone!

I got a lot of great responses for this question! The answer is it would cause an EPSP. My reasoning is as follows:

Now we have chloride with an equilibrium potential that is more positive (between -55 mV and -70 mV). Normally, the chloride ions flow inward. However now the ions will be flowing outwards instead of inwards, right? In order to reach this now more positive equilibrium potential, the negative charge has to flow out, causing the cell to depolarize. So increasing the permeability of the chloride would then cause an EPSP.

Best of Luck! Keep up the good work!

Megan