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Repolarization of the Postsynaptic Neuron Membrane

  • Following a brief period of image descriptiondepolarization, the postsynaptic membrane repolarizes to its resting potential within a few milliseconds (ms).
An image showing a neuron cell membrane enlarged and contains channels (leaking and ATPase) to move the ions out and inside the cell
An image showing depolarization of a neuron cell membrane on the green board
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  • The process begins when the neurotransmitter, acetylcholine (ACh), is image descriptionbroken down (catalyzed) by the enzyme, acetylcholinesterase (AChE), which is present in the postsynaptic membrane and synaptic cleft. Choline, one products of the reaction, is taken back up by the presynaptic neuron and used to make new ACh.
  • As the ACh is removed, the gated receptors (= ion channels) in the postsynaptic membrane image descriptionclose. This blocks the diffusion pathways for Na+ and K+ and stops further depolar-ization.
  • After the channels close, Na+ and K+ that passed through the membrane during depolarization are redistributed by image descriptionNa+/K+ pump proteins.
  • The pumps actively move Na+ ions out of the cell and K+ ions in.
  • Leak channels then allow K+ ions to image descriptiondiffuse back out of the cell.
An image showing depolarization of a neuron cell membrane on the green board
An image showing Repolarization of a neuron cell membrane on the green board
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