Problem 17 Nerve cells are connected by extensions called axons. An axon has a voltage across its membrane which acts like a capacitor (two oppositely charged surfaces). When the nerve cell fires, it discharges like a capacitor. This is called membrane depolarization . Think of an axon as a coaxial cable with a capacitance of L C = 2k In(RR; ) R., and R. are the inner and outer radii of the membrane. For a derivation, see Example 24.4 in the textbook. I expect you to understand the derivation of the capacitance of a coaxial cable. The speed with which a signal moves down the axon depends on the discharge rate (smaller capacitances discharge faster). The question: The membranes of some axons are covered with a fatty insulator called myelin that makes the membrane thicker (as if increasing the distance between the capaci- tor plates). Will myelinated axons transmit signals faster or slower than unmyelinated axons? Hint: A myelinated axon has a larger R. (think of R, as fixed)