Nerve Impulses

Nerve Impulses

A nerve impulse:

• is a temporary reversal of potential difference across the axon membrane that travels as a self-propagating action potential
• the reversal of potential difference is caused by ion movement across the membrane - sodium ions (Na+) and potassium ions (K+)
• action potentials can only be generated where the axon membrane is not insulated by a myelin sheath so they jump from a node of Ranvier to the next adjacent node of Ranvier in myelinated neurones - saltatory conduction

Establishment of Resting Membrane Potential:

• In a resting (unstimulated) neurone the membrane is polarised
• The inside of the cell has a negative charge with respect to the outside of the cell
• Potential difference across membrane is -70mV
• But...
  • when the potential…