Background Knowledge

Question 0

What is equilibrium potential?

Answer 0

In a single ion system, the voltage at which there is no net flow of that species of ion across the membrane

Question 1

What is membrane potential?

Answer 1

Voltage difference across a membrane

Question 2

What is reversal potential?

Answer 2

• Nernst potential
• The voltage at which there is no net flow of ions (of all species) across the membrane (if there is just one ion it’s same as equil. potential)
• Can be calculated using Nernst equation
• If one ion Chanel type dominates (high permeability) membrane potential tends towards reversal potential for that ion

Question 3

How do electrical signals transmit information?

Answer 3

By travelling along the dendrites and axons of neurones

Question 4

Describe the two forms of electrical signals

Answer 4

• Action potentials, brief depolarisations generated by voltage-gated Na and K channels. They propagate actively through the neurone and do not decrement in size
• Graded responses, passively propagating, decrementing changes in membrane potential

Question 5

What follows an action potential?

Answer 5

Refractory period - membrane is inexcitable because Na+ channels are closed & inactivated and K+ channels are open. Limits maximum firing rates