Nervous system - Lecture Eighteen : Neurophysiology I - The action potential
3 important questions on Nervous system - Lecture Eighteen : Neurophysiology I - The action potential
Understand and explain the Depolarisation, Repolarisation and Hyperpolarisation graph ?
DEOLARISATION :
Membrane potential becomes more positive. Causes Na+ channels to open, allowing Na+ influx into the cell.
REPOLARISATION AND HYPERPOLARISATION :
Membrane becomes more negative.
- R : From the maximum depolarized value back to RMP.
- H : From RMP to a more negative potential.
K+ channels open, allowing K+ efflux out of the cell.
Membrane potential becomes more positive. Causes Na+ channels to open, allowing Na+ influx into the cell.
REPOLARISATION AND HYPERPOLARISATION :
Membrane becomes more negative.
- R : From the maximum depolarized value back to RMP.
- H : From RMP to a more negative potential.
K+ channels open, allowing K+ efflux out of the cell.
What is a Action Potential ?
An action potential is a temporary maximum depolarisation which propagates along the axons. It occurs when a local depolarisation reaches threshold potential (59mV)
Explain the two different types of Refractory periods ?
ABSOLUTE :
- From the maximum depolarised value to the period of hyperpolrisation. Another action potential is not possible because the Na+ channels are unresponsive.
- From the period of hyperpolarisation back to the Resting membrane potential. Na+ channels are responsive but it is harder to generate another action potential because the membrane is hyperpolarised.
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