Action Potential

Question 1

Define an AP

Answer 1

Brief transient reversal of membrane potential that sweeps along membrane of neuron

Question 2

Give the equation for the conductance of a K+ channel population

Answer 2

gK = IK/(Vm-EK)

Question 3

Define the all-or-none rule

Answer 3

AP either reaches full amplitude or does not occur at all

AP amplitude independent of stimulus amplitude that elicited it

Question 4

Define threshold

Answer 4

Value of Vm where net ionic current (INa + IK + IL) changes from outward to inward, depositing positive charge inside membrane

Question 5

Define refractory period

Answer 5

Brief period when it is more difficult to excite a neuron to generate another AP

Question 6

Give the equation linking change in voltage with change in capacitance and current

Answer 6

ΔV = Δ(Q/C)

Question 7

Give the equation linking axial resistance with resistivity and section area

Answer 7

Ra = ρ x 1/As
As = section area
Ra = ρ x 1/πr^2

Question 8

Give the equation linking capacitance with lateral SA

Answer 8

Cm = (ε x εo x AL)/d
d = thickness of insulator
AL = lateral SA
Cm = (ε x εo x 2πrl)/d

Question 9

Give the equation for rate of passive AP spread

Answer 9

1/RaCm

Question 10

Define myelination

Answer 10

Wrapping of glial cell membranes around an axon