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Get Full Access to University Physics - 13 Edition - Chapter 23 - Problem 37e
Get Full Access to University Physics - 13 Edition - Chapter 23 - Problem 37e

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# Axons. Neurons are the basic units of the nervous system. ISBN: 9780321675460 31

## Solution for problem 37E Chapter 23

University Physics | 13th Edition

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Problem 37E

Axons. Neurons are the basic units of the nervous system. They contain long tubular structures called axons that propagate electrical signals away from the ends of the neurons. The axon contains a solution of potassium (K+) ions and large negative organic ions. The axon membrane prevents the large ions from leaking out, but the smaller K+ ions are able to penetrate the membrane to some degree (Fig).This leaves an excess negative charge on the inner surface of the axon membrane and an excess positive charge on the outer surface, resulting in a potential difference across the membrane that prevents further K+ ions from leaking out. Measurements show that this potential difference is typically about 70 mV. The thickness of the axon membrane itself varies from about 5 to 10 nm, so we’ll use an average of 7.5 nm opposite charge densities on its faces. (a) Find the electric field inside the axon membrane, assuming (not too realistically) that it is filled with air. Which way does it point: into or out of the axon? (b) Which is at a higher potential: the inside surface or the outside surface of the axon membrane? Figure:

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Solution 37E The relationship between potential difference and electric field is given by V = Ed, where V is the potential difference, E is the electric field and dis the distance to the point where from a charge where potential difference has to be measured. Given, potential difference V = 70 mV = 70 × 10 3V Thickness of the membrane d = 7.5 nm = 7.5 × 10 9 m 3 9 (a) Therefore, the electric field E = V /d = (70 × 10V )/(7.5 × 10 )m 6 E = 9.3 × 10 V /m This is the required magnitude of the electric field inside the axon membrane. The field will be point into the axon. (b) The outside surface of the axon membrane will be at higher potential as it has an excess of positive charge.

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##### ISBN: 9780321675460

The full step-by-step solution to problem: 37E from chapter: 23 was answered by , our top Physics solution expert on 05/06/17, 06:07PM. Since the solution to 37E from 23 chapter was answered, more than 509 students have viewed the full step-by-step answer. This full solution covers the following key subjects: axon, membrane, ions, surface, Charge. This expansive textbook survival guide covers 26 chapters, and 2929 solutions. This textbook survival guide was created for the textbook: University Physics, edition: 13. The answer to “Axons. Neurons are the basic units of the nervous system. They contain long tubular structures called axons that propagate electrical signals away from the ends of the neurons. The axon contains a solution of potassium (K+) ions and large negative organic ions. The axon membrane prevents the large ions from leaking out, but the smaller K+ ions are able to penetrate the membrane to some degree (Fig).This leaves an excess negative charge on the inner surface of the axon membrane and an excess positive charge on the outer surface, resulting in a potential difference across the membrane that prevents further K+ ions from leaking out. Measurements show that this potential difference is typically about 70 mV. The thickness of the axon membrane itself varies from about 5 to 10 nm, so we’ll use an average of 7.5 nm opposite charge densities on its faces. (a) Find the electric field inside the axon membrane, assuming (not too realistically) that it is filled with air. Which way does it point: into or out of the axon? (b) Which is at a higher potential: the inside surface or the outside surface of the axon membrane? Figure:” is broken down into a number of easy to follow steps, and 193 words. University Physics was written by and is associated to the ISBN: 9780321675460.

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