MOVEMENT OF IONS

• HOW IS MOVEMENT OF IONS CONTROLLED ACROSS THE MEMBRANE?

  • phospholipid bilayer
  • channel proteins
  • carrier proteins
• WHAT DOES THE PHOSPHOLIPID BILAYER OF THE AXON CONTROL?

  prevents ions from simply diffusing across it
• WHAT DO THE CHANNEL PROTEINS DO?

  act as ion channels (some have gates/ others are always open) for facilitated diffusion
• WHAT DO CARRIER PROTEINS DO?

  actively transport sodium ions out of the axon and potassium ions into the axon

  -> known as the sodium-potassium pump