Membrane and action potentials

• Which ions are responsible for action potentials.

  Na+ and K+.
• What is the electrochemical driving force.

  Combination of the Chemical [gradient] and Electrical [Charge] forces.
• Two types of ion channels

  1. Gated
  2. leaky
• Types of gated channels.

  1. Voltage
  2. Mechanical
  3. Ligand
• How is the resting membrane potential generated.

  1. K+ OUT [Leaky]
  2. 3Na+ OUT [Pump]
  3. 2K+ IN [Pump]
• What is the name of the membrane pump.

  Na+/K+ ATPase pump.
• What is the resting membrane potential. 


  -70mV.
• Which equation calculates resting membrane potential. Which ions does it account for.

  1. GHK.
  2. Na+
  3. K+
  4. Cl-
• Define resting membrane potential. 


  Difference in charge accross the membrane.
• The resting membrane is polarised. True/False.

  True.
• What is equilibrium potential.


  The membrane potential to exactly counteract chemical forces acting on a particular ion.
• Which equation calculates Equilibrium potential.


  Nernst equation.
• Which channels open to reach the threshold potential. 


  Ligand-gated Na+ channels.
• What is the threshold potential value.


  -55mV.
• What causes the membrane to become depolarised. 


  Voltage-gated Na+ channels open.
• How are Voltage-gated Na+ channels innactivated.

  Innactivation gate plugs the pore.
• What causes repolarisation of the membrane. 


  Voltage-gated K+ channels open.
• Why does the membrane beocme hyperpolarised. 


  Voltage-gated K+ channels close slowly.
• What is the refractory period. What does it do. 


  When the membrane potential is below the resting potential.

  The neurone is unable to fire another action potential.