Nervous System
- Created by: Anna
- Created on: 06-03-15 12:48
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- Nervous System
- Resting Potential POLARISED
- More -ive inside - 70mV lower
- Maintained by Na/K Pumps = POLARISED
- Na+/K+ Pump
- 3Na+ out for every 2K+ In
- Against conc grad
- Maintained by Na/K Pumps = POLARISED
- Active= +ive +40mV
- Inactve= -ive -70mV
- More -ive inside - 70mV lower
- Action Potential DEPOLARISED
- Na+ channels open
- Inside becomes less positive
- = Depolarised. +40mV potential diff
- Na+ channels close
- K+ channels open
- K+ moves out
- positive charge inside removed
- Potential diff starts 2 return to norm = Repolarisated
- K+ moves out
- K+ channels open
- Na+ channels close
- = Depolarised. +40mV potential diff
- Inside becomes less positive
- If stimulus is strong and reaches threshold voltage gated channels open
- Na+ channels open
- Inside becomes less positive
- = Depolarised. +40mV potential diff
- Na+ channels close
- K+ channels open
- K+ moves out
- positive charge inside removed
- Potential diff starts 2 return to norm = Repolarisated
- K+ moves out
- K+ channels open
- Na+ channels close
- = Depolarised. +40mV potential diff
- Inside becomes less positive
- If stimulus doesn't reach threshold = no depolarisation
- Na+ channels open
- Na+ channels open
- Restoring Resting Potential
- More K+ leaves than needed = Hyperpolarised
- Refractory Period occurs
- K+channels eventually close
- Another Impulse cannot occur during this
- Ensure impulse travels in 1D
- Refractory Period occurs
- More K+ leaves than needed = Hyperpolarised
- All or Nth Law
- Unless threshold reached by stimulus no action potential
- Size of impulse independent of stimulus intensity
- More Intense Stimulus = Greater Frequency of Action potentials
- Factors affecting Transmission Speed
- Axon Diameter
- Wider axon = faster impulse
- Myelin Sheath
- Increases Speed of impulse
- Impulse jumps node to node
- Impulse jumps node to node
- Increases Speed of impulse
- Temperature
- Axon Diameter
- Saltatory Conduction
- Latin 'Saltare' - to leap
- Latin 'Saltare' - to leap
- Resting Potential POLARISED
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