neurones

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  • neurones
    • sensory
      • transmit nerve impulses from receptor to CNS
      • short dendrites, one long Dendron, short axon
      • sensory receptors convert an impulse into electrical energy (transducers)
    • resting potential
      • na+ and k+ pumps use active transport. 3 na+ out for ever 2 k+ in
      • -70mV
      • Na+ cant diffuse back in, creating electrochemical gradient
      • potassium ion channels open so k+ can diffuse out as well as being pumped in
      • outside of membrane is positively charged, inside is negatively charged
    • generator potential
      • when stimulus is detected the membrane becomes more permeable allowing ions in and out
      • this alters the potential difference.
    • action potential
      • when the generator potential reaches threshold frequency an action potential will occur
        • generator potential
          • when stimulus is detected the membrane becomes more permeable allowing ions in and out
          • this alters the potential difference.
      • a stimulus causes excitement, sodium channels open, diffuse down gradient
        • inside becomes less negative
      • depolarisation is when potential diff. reaches -55mV voltage gates channels open
        • more Na+ enter/ flood in
      • Repolarisation is when potential difference is +30mV.
        • sodium channels close, potassium ones open
          • k+ diffuse out down concentration gradient
      • hyper polarisation
        • K+ channels are slow to close. too many diffuse out
        • neurone goes past -70mV

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