The Nerve Impulse

Ashley Jeckel & Emily Cassady

Resting membrane conditions

  • Membrane permeability- semipermeable to ions that are needed to maintain homeostasis

  • Ions: K+ and Na+ (mostly)

    - negative charge within the cell is created by the cell membrane being more permeable to K+ movement than Na+ movement

Generation of a nerve impulse

Stimuli- things such as smells, sights, or feeling something that can cause a reaction with the neurons.

depolarization- a positive-going change in a cell's membrane potential, making it more positive, or less negative, and thereby removing the polarity that arises from the accumulation of negative charges on the inner membrane and positive charges on the outer membrane of the cell.

permeability- generally, a cells membrane is semi-permeable but when more of an ion is needed, then the membrane becomes especially permeable to that neuron.

Protein channels- located in the membrane of a cell, these proteins are used with active transport of larger particles across the cell membrane such as glucose.

Conduction of the impulse

Neurons and neurons

Conduction of the impluse

  • action potential: a short-lasting event that causes an "electrical charge" in which a cells "potential" rises and falls
  • ion movement: Na+ goes in and K+ goes out
- K+ leaves more rapidly than Na+ enters: this maintains a resting potential (3 Na+ for 2K+)
  • protein channels:
  • myelin sheath: myelination helps coordination and control
- decreases the amount of time it takes to "feel" sensations and react properly

Membrane proteins

These proteins are located inside the membrane and like the channels, they help make the particles move in and out of the cell quickly and easily. Generally, they are only used with active transport.