Establishing Membrane Potential

Question 1

What is the result of thermodynamic equilibrium?

Answer 1

Cell death

Question 2

What is potential energy?

Answer 2

• ability to do work
• implies the presence of force
• difference between two points (ie - gradient)

Question 3

What provides the basis of the action potential in excitable cells?

Answer 3

concentration and electrical gradient

Question 4

In the Nernst equation, what does [X]ref stand for?

Answer 4

Concentration of ion X outside the cell

Question 5

In the Nerst equation, what does [X]sense stand for?

Answer 5

Concentration of ion X inside the cell

Question 6

What are the functions of the Nernst Equation?

Answer 6

• defines equilibrium
• defines direction an ion will flow given current conditions
• defines membrane potential (Vmem) if the membrane is permeant to ONLY 1 ion

Question 7

Primary Determinants of Vmem

Answer 7

Requirements:

• gradient
• conductive pathway
• charge carrier
• power source

These are the minimum requirements to establish resting membrane potential

Question 8

What does flux rely on?

Answer 8

concentration and electrical gradients

Question 9

What is net flux dependent on?

Answer 9

Sum of the forces

Question 10

Summary of the Nernst Equation

Answer 10

• includes concentration and electrical gradients

- can be used to describe systems at equilibrium OR determine direction of flux in current conditions