So, if your cell is in resting state (-70 mV), and it gets hit with an action potential. The action potential takes the cell and brings it above -50 mv which is the threshold, or does it take it way beyond the threshold.

I always thought they take it beyond the threshold. But now that im thinking about it, if it does how could K come in without polarizing it a rediuclous amount.

Ben and nihlthak where u guys at

This post was edited by impulse155 on Jan 5 2012 01:36pm

But then what are the net ionic flows during each.

Na flows in causing an increase in potential (more positive)
correct?
Not Na flows in making in engative.
Omfg if i had this confused and thats why i was fucking it up...

I took an intro to biomedical rehabilitation engineering course where we spent about a week on action potentials. Other than that, my last bio course was in high school. I am absolutely not someone you want to be asking about this

But...you know everything....

I have no doubt in my mind that I could figure it out eventually, but I don't know it right now, lol

This is a rather ambiguous way to say it, but you seem to have a handle on it.

Outside influence would bring the cell from -70 up to the threshhold to begin an action potential.

After the cell reaches threshhold, action potential happens, which invloves potassium and sodium ion channels opening up temporarily in a sequence.

First, positive sodium ion channels open, and the ions rushing in increase voltage and cause the sharp spike seen in the action potential diagram. Then, opened potassium channels would send intracellular potassium ions outside of the cell and lower the potential to almost normal levels. Afterward, the sodium potassium pump brings voltage back to pre-action potential levels.

Things that depolarize the membrane would cause an action potential since it makes voltage go up from -70.

Things that hyperpolarize the membrane prevent action potentials since they make voltage go down from -70.

A negatively charged ion leaving the cell would have the same effect as a positively charged ion entering the cell. In this case, increase in voltage.

@bolded: the Na/K channel is 3 Na out for 2 K in if I remember correctly, its a passive channel, which means it does it more or less automatically to recharge the inside of the cell with more K to pump it out in the event of another activation