Resting state

• what are the cell membranes of neurones like at rest?


  polarised
• Why is the membrane polarised in a neurone's resting state?


  The outside of the membrane is +ively charged compared to the inside - this is because there are more +ive ions outside the cell than inside
• What is a neurones resting state?


  when it is not being stimulated
• what does it mean if the membrane is polarised?


  There is a difference in charge (called a potential difference/ voltage) across it
• What is the voltage across the membrane when it is at rest CALLED and WHAT IS IT?


  Called the resting potential - it is about -70mV
• What are mV?


  millivolts
• What creates and maintains the resting potential?

  Sodium-potassium pumps and potassium ion channels in a neurone's membrane
• What do the sodium-potassium pumps do?

  Move sodium ions out of the neurone, but the membrane is not permeable to sodium ions, so they CANNOT diffuse back in.

  This creates a sodium ion electrochemical gradient because there are MORE +ive sodium ions outside the cell than inside.

  (This makes the outside of the cell positively charged compared to the inside ?)
• What is an electrochemical gradient?


  a concentration gradient of ions
• What do the sodium-potassium pumps ALSO do?

  Move potassium ions in to the neurone, but the membrane is permeable to potassium ions so they diffuse back out through potassium ion channels

  This makes the outside of the cell positively charged compared to the inside
• What are all types of TRANSPORT PROTEIN?

  • Sodium-potassium pump
  • Potassium ion channel
  • Sodium ion channel