Topic 30

Question 1

Describe electrochemical potential

Answer 1

The sum of the electric and Chemical potenitals

Question 2

Give the Nernst-Equation

Answer 2

• R = Gas Constant*
• T = Temperature*
• F = Faraday Constant*

Question 3

What is the nernest equation used for

Answer 3

Calculating the Electrochemical potential of an ion

Question 4

Compare Calculated and Measured resting potentials

Answer 4

Calculated values arent always best:

Cell is not a closed system (As regarded in formula)

Ions are assumed to be perfectly immobile

Dependent on the composition of the membrane

The model considers only one type of ion at a time

Question 5

What are the ion currents accross a mammalian axon membrane?

Answer 5

Ionic current due to Concentration difference (I_c)

Ionic current due to potential difference (Ip)​

Question 6

Describe the ion currents by Na⁺

Answer 6

Both I_c and I_p are directed into the cell, concentration of Na⁺ is still bigger outside.

Sodium must be continually brought back against the differences.

Question 7

Describe the ion currents by Cl^-

Answer 7

I_c = I_p, They compensate eachother

Question 8

Describe the ion currents by K⁺

Answer 8

I_c > I_p, there must be a mechanism to return K⁺ to the cell.

Question 9

Na/K ions diffuse by…

Answer 9

Passive flow

Question 10

Describe the Na/K pump

Answer 10

Na⁺ out of cell / K⁺ Into the cell

Ratio of 3Na⁺:2K⁺

Uses ATP