Basic neuro concepts

Question 1

Voltage

Answer 1

Work done(J) when charge(q) is moved
Volts
V = J/q

Question 2

Ohms Law

Answer 2

States that current (I) flowing between two points is directly proportional to voltage

I = V/R

Question 3

Conductance

Answer 3

Reciprocal of resistance
Measured in Siemens
The ease with which electric current will flow

I = GV

Question 4

Capacitance

Answer 4

The ability to store charge - the quantity of charge required to create a potential difference between two conductors

C = q/V - measured in farads (F)

Question 5

The lipid bilayer

Answer 5

Acts as a capacitor - mutual capacitance
Insulator that separates two conductors i.e. intra/extracellular solutions
Greater surface area of neuron = larger capacitance

Question 6

Total membrane capacitance

Answer 6

C = CmA
Cm = specific membrane capacitance –> dependent on thickness of bilayer
A = surface area of membrane

Question 7

Capacitive current (Ic)

Answer 7

Rate of change of capacitance charge
Ic = dQ/dt Ic = C(dV/dt)

Question 8

Membrane time constant (Tm)

Answer 8

Tm = rm x Cm
rm = membrane resistance
Cm = membrane capacitance
Progation velocity is inversely proportional to capacitance of axon

Membrane time constant is the time for the potential to fall from the resting to a fraction (1-l/e), or 63%, of its final value in the charging curve during the application of a small negative current pulse.

Question 9

The effect of myelin

Answer 9

Increases distance between conductors
Reduces capacitance of axonal membrane
Less charge stored under membrane