Is the outer surface of a nerve impulse normally negative and the inner part usually positive?
1 Answer
No. When a neuron is not carrying an impulse, the inside of the axon is negative and the outside is positive.
Explanation:
The cell membrane has a different permeability for different ions.
1. A process called the sodium-potassium pump uses ATP to pump out three
2. The membrane has ion channels that allow
3. Negatively charged proteins inside the cell cannot pass through the membrane.
In the resting state, these three mechanisms make the inside of the membrane more negative than the outside by about -70 mV.
The diagram below shows a resting neuron. The + signs represent cations and the - signs represent anions.
(From www.apsubiology.org)
The video below shows how the membrane potential is generated and maintained by using the sodium-potassium pump and potassium channels.
