Electrical Activity of Cells

Question 1

What is the value for Ek and for Ena?

Answer 1

Ek is -90mv and Ena is +60mv

Question 2

If a cell potential is close to -90mv, what does this stop?

If a cell potential is close to +60mv, what does this mean?

Answer 2

Stops K+ leaving

Stops Na+ entering

Question 3

Why is the electrical potential of a cell much closer to Ek than Ena?

Answer 3

The cell membrane is about 50 times more permeable to K+ than Na+. There are more K+ channels open at rest.

Question 4

Why at -90mv does the potassium not leave the cell?

Answer 4

So that the cell does not lose positive charge

Question 5

What is the equation for the driving force on an ion?

Answer 5

Membrane resting potential - the equilibrium potential

Question 6

Why is less force needed to push potassium out then needed to get sodium in?

Answer 6

There are more potassium channels in the membrane.

Question 7

What does the Nernst equation assume that the Goldman Hodgkin Katz equation takes into account?

Answer 7

That the permeability of the membrane from sodium and potassium is equal.

Question 8

How do you use the Nerst equation?

Answer 8

58 X log (shown below)

The log = add the permeabilities of potassium and sodium out the cell divided by the permeabilities of in the cell added