Module 2 - Class 4

Question 1

transmembrane potential (Vm)

Answer 1

a voltage difference across the cell membrane that can be measured using a pair of electrodes.

always reported as the potential inside of the cell relative to the extracellular space.

Question 2

Depolarization

Hyperpolarization

Repolarization

Answer 2

1)Vm becomes less negative
2) Vm becomes more negative
3)Vm returns toward the resting potential.

Question 3

Current (I)
Resistance (R)
Voltage (V)

Answer 3

Current (I) is a flow of charge from one location
to another
Resistance (R) measures how difficult (energy-
intensive) it is for current to flow
Voltage (V) acts as a force, providing energy
for current flow

Question 4

Factors that affect electromotive force (EMF):

Answer 4

.Transmembrane potential (Vm)
• Ion valence (aka. charge, z)
• Faraday’s constant (F)

Question 5

Factors that affect diffusion/diffusive force

Answer 5

• Concentration gradient (out/in)

• Temperature (T)

• Gas (diffusion) constant (R)

Question 6

Ions have two key properties that can affect how they move
What are those properties?

Answer 6

1. Concentration: like any molecule, ions obey the law
   of diffusion, and tend to spread from areas of high to areas of low concentration.
2. Charge: molecules with a charge (+ or -) are repelled

Question 7

To generate any transmembrane potential requires:

Answer 7

1. Unequal distributions of ion species across the two sides
   of a membrane (concentration differences)
2. Selective permeability of that membrane to different ion
   species