BRAINCAKENerve Impulses
A nerve impulse is a self-propagating wave of electrical activity that travels along the membrane of a neurone. It is not a flow of electrons as in a wire, but a change in the potential difference across the cell surface membrane caused by the movement of ions.
The ions involved are mainly sodium ions (Na+) and potassium ions (K+). Being charged, they cannot diffuse through the phospholipid bilayer, so they move through specific channel proteins and are moved by carrier proteins in the membrane. Opening and closing these channels changes the charge inside the axon relative to the outside.
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More in Mammalian Nervous System
- Nervous System
- Structure and Function of Neurones
- Myelinated Neurones
- Speed of Nerve Impulses
- Investigating Nerve Impulses
- Resting Potential
- Action Potential
- Depolarisation
All 38 lessons in Mammalian Nervous System · All Edexcel A-level Biology topics