Calculate the capacitance, C, of an axon that is 10 cm long and has a radius of

Question

Calculate the capacitance, C, of an axon that is 10 cm long and has a radius of 10 m. Given a typical membrane thickness of 10.8 m and a dielectric constant for cellular fluid of 3, what is the capacitance of the axon? Let 8.85 x 10-12 C2/New m2. 2. Now, to continue with #2, calculate the changes in [Na+] due to an action potential. In other words, by what factor does the [Na*]i change because of an action potential firing? Assume that Vm =-70 mV, the Vo = 40 at the peak of the AP, the initial [Na ]i 15 mM. 3.

Explanation / Answer

Capacitance of capacitor is given by C = ( k A /d)
Given d= 10* 10 ^(-6) m

A= thickness * length = 10^-8 * 10* 10^-2 = 10^-9 m^2

After substututing the above values we get

C= (8.85* 10^-12 * 3 * 10^-9)/(10^-5)

C=2.655 * 10^-15 C^2/New. metre

-----------------------

The concentration of Sodium doesn't change much during an action potential. It remains the same, since only few number of ions move in and out of the axon during the action potential.

Hence the concentration is 15mM.

Related Questions

Navigate

• Browse (All)
• Browse C
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.