Modulating membrane potential

Question 1

What does the GHK equation measure?

Answer 1

Equilibrium for multiple ion species

Question 2

How is the permeability of an ion measured in the GHK equation?

Answer 2

Relative to a benchmark ion (usually Pk+ = 1)

Question 3

If the membrane potential is more positive than the Nernst potential for a cation, will the cation enter or leave the cell? Anion?

Answer 3

Cation will leave

Anion will enter

Question 4

If the membrane potential is more negative than the Nernst potential for a cation, will the cation enter or leave the cell? Anion?

Answer 4

Cation will leave

Anion will enter

Question 5

If the membrane potential is +50mV, what is the relationship between PNa and PK+?

Answer 5

PNa (+60mV) is more dominant than PK (-90mV)

Question 6

What is the typical relationship between PK and PNa? Why?

Answer 6

PK&raquo_space; PNa

Typical resting membrane potential is -90mV

Question 7

An increase in the permeability of what initiates the action potential?

Answer 7

Cation channel

Question 8

A increase in permeability of what causes the upstroke of the action potential?

Answer 8

Sodium

Question 9

An increase in permeability of what causes downstroke of action potential?

Answer 9

Potassium

Question 10

Changes in what will modify the action potential?

Answer 10

Chloride

Question 11

What can cause changes to PNa?

Answer 11

Local anesthetics (lidocaine)

Question 12

What can cause changes to PCl?

Answer 12

General ansthetics (Barbiturates)

Question 13

What diseases can alter extracellular Potassium, Sodium & Chloride?

Answer 13

Addisons

Renal failure