BRAINCAKEResting Potential
When a neurone is not transmitting an impulse, there is a potential difference of about −70 mV across its membrane, with the inside negative relative to the outside. This is the resting potential, and the membrane is said to be polarised.
Three factors produce the resting potential.
1. The sodium-potassium pump. This carrier protein uses ATP to actively transport 3 Na+ out of the axon for every 2 K+ in. This sets up concentration gradients: Na+ is more concentrated outside and K+ more concentrated inside. Because more positive charge leaves than enters, the pump also makes the inside slightly more negative.
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More in Mammalian Nervous System
- Nerve Impulses
- Myelinated Neurones
- Speed of Nerve Impulses
- Investigating Nerve Impulses
- Action Potential
- Depolarisation
- Repolarisation
- Hyperpolarisation
All 38 lessons in Mammalian Nervous System · All Edexcel A-level Biology topics