Membrane Potential And Action Potential

Question 1

Cell membrane is…

Answer 1

A lipid bilayer.
An electrical insulator.
A transport barrier - fat soluble can get through, hydrophobic can’t.
Contains membrane proteins eg K+/Na+ pump.
Contains Ion channels eg K+ channel and Na+ channels.

Question 2

Resting membrane potential is…

Answer 2

When the electrical charge of the cell matches the concentration gradient.
Equilibrium.
Different cells have different potentials.

Question 3

Sodium channels…

Answer 3

Na selective
Voltage activates channel
Channel opens from resting state with depolarisation
Na enters cell down concentration gradient
Positive feedback
Further depolarisation towards reversal (+67mV)

Question 4

Voltage activated Na channels

Answer 4

In presence of depolarising stimulus channel moves slowly into inactive state.

Once depolarization finishes then can return to resting state.

Voltage sensitive activation, inactivation, deactivation.