Transmission of action potential

• What is action potential (nerve impulse)?


  The change in electrical potential along the membrane of a nerve or muscle cell
• What ions are in higher concentration in the cell?

  Potassium ions (K+)
• What ions are in higher concentration outside the cell?

  Sodium ions (Na+)
• When the potential differences reaches a reduced voltage what happens?

  causes hundreds of sodium gates in the membrane to open briefly
• What is myelin made from?

  Flattened layers of specialised cells called the Schwann Cells
• How is a myelin sheath formed?

  The cells wrap around the axon and form a lipid insulating layer around the neurone
• What is myelination of neurone?


  the nerve impulse travels faster if the neurone is myelinated
• What is hyperpolarisation ?

  the potential increases and becomes more negative than the resting potential

  some K+ channels remain open and Na+ channels reset.
• What direction does hyperpolorisation take the signal?

  One direction only