Biological electricity Flashcards
How is energy developed
Ion imbalance across cell (inside-out)
What is saltatory conduction
Transmit change by reversing local electric field that passes along nerve axon - active signal
Regenerated along axon
Are biological material good conductors
Very poor
Why can passive electric potentials only spread a few mm
They are dissipated by resistance
What is the potential difference across neurone
-70mv (inside-out)
Why are resting potentials important and where are they derived from
Essential for excitable cells to generate action potential FROM: Electrolytes in physiological fluid Large protein anions in cell Semi-permeable membrane Sodium/Potassium pump
What causes the 70mv potential
Potassium imbalance on either side of membrane
What makes the inside of a cell negative
Large protein ions
What is the Gibbs-Donnan equilibirum
Potassium move into cell to maintain electrochemical neutrality
What ‘attracts’ potassium into cell
Protein anions
What is the Nernst equation and the units
Vm = 58 log Potassium out/Potassium in
Units mV
How is the gradient maintained
3 sodium ions out
2 potassium ions in
Can nerve axon generate bigger signals
Can only generate more NOT bigger
Where is an action potential generated
Axon hillock
When are the sodium voltage-gated channels opened
NOT resting potential
OPEN when membrane depolarised - causes conformational change
