Answer: The correct question is
During an action potential, Na+ ions move into the cell at a rate of about 3×10−7mol/m2⋅s.
How much power must be produced by the "active Na+ pumping" system to produce this flow against a +30−mV potential difference? Assume that the axon is 70 cm long and 30 μm in diameter.
Explanation:
length of axon is 70cm= 0.7m
potential difference= 30mv = 30/1000= 0.03V
Diameter= 30цm
Radius= 30цm/2= 15Цm= 15 x 10⁻⁶m
area= 2πrl= 2 x 3.14 x 15x 10⁻⁶m x 0.7 =0.0000659
P= QV/t where P= power, Q is charge, V is potential difference and t is time.
Q/t = avogadro*number of ions*area*e⁻charge
=(6.02 x 10²³)(3 x 10⁻⁷)(0.0000659)(1.6 x 10⁻¹⁹) =0.0019 x 10⁻³c/s
Power = 0.0019 x 10⁻³c/s x 0.03V = 5.7 X 10⁻⁸W
