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What is the main purpose of the sodium potassium pump in the nervous system?Are signals...

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lillyjenbest | (Level 1) eNoter

Posted April 19, 2011 at 9:33 AM via web

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What is the main purpose of the sodium potassium pump in the nervous system?

Are signals transferred across the axon via the na/k pump or does it mainly reset the na and k levels after action potential? 
Maybe I'm a little confused as to how the signal or impulse is moving through the neuron....


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boblawrence | (Level 1) Associate Educator

Posted October 27, 2011 at 3:47 AM (Answer #1)

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The Sodium-Potassium Pump (Na-K Pump) was discovered in the 1950’s by Skou, who won the Nobel Prize in 1997.  It is the mechanism used by the cell to preserve a high intracellular concentration of Potassium and low concentration of Sodium, compared to opposite concentrations in the extracellular fluid.  The cell membrane has a protein channel that uses ATP energy to create the Na-K gradients for cell function.  The channel has an affinity for sodium ions.  When they enter the channel the protein changes shape, allowing potassium to move against gradient.  The process is reversible.

Highly excitable cells such as neurons are able to respond to stimuli and transmit impulses, and the Na-K Pump is needed for this activity.  Neurons preserve their membrane potential by creating high intracellular potassium and low sodium.

The Na-K Pump resets the neuron to its resting potential after an action potential has been transmitted.  Thus, it is not the Na-K Pump that transmits the signal, but instead it resets the cell membrane to allow it to transmit another action potential.  The electrical impulse of the action potential triggers the release of neurotransmitter at the synaptic gap.  It is the neurotransmitter, which crosses the gap and fires the second neuron.

The Na-K Pump maintains a nerve in a polarized state (also called resting potential), ready to be triggered by an Action Potential.  With passage of the Action Potential there is a sudden depolarization of the neuron, causing opening of voltage-activated channel at which point the Na-K Pump reverses and resets the membrane to resting potential, ready for the next Action Potential.  During the reset process the neuron is in a refractory period.

Thus, the Na-K Pump sets and resets the cell membrane to allow it to transmit the Action Potential.  The Action Potential causes the release of the neurotransmitter, which passes the signal to the next nerve.

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