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Depolarization of the Postsynaptic Neuron Membrane

  • While the postsynaptic neuron is at rest, Na+ / K+ pump proteins actively concentrated Na+ ions outside the cell and K+ ions inside the cell. Many of the K+ ions diffused back across the membrane through leak channels, making the cell’s interior relatively negative (polarized to -70mV).
  • Depolarization of the postsynaptic membrane begins when ACh is released by the presynaptic neuron and image descriptionbinds to receptors in the postsynaptic membrane.
An image showing ACh molecules binding to the receptor of a neuron cell membrane
An image showing ACh molecules binding to the receptor of a neuron cell membrane
An image showing ACh molecules binding to the receptor of a neuron cell membrane
An image showing ACh molecules binding to the receptor of a neuron cell membrane
An image showing ACh molecules binding to the receptor of a neuron cell membrane
An image showing ACh molecules binding to the receptor of a neuron cell membrane
An image showing ACh molecules binding to the receptor of a neuron cell membrane
  • Chemical gates image descriptionopen in response and the┬áreceptors form water-filled channels, which Na+ and K+ ions pass through.
An image showing the opening process of a gate to let the molecules pass through it
An image showing the opening process of a gate to let the molecules pass through it
An image showing the opening process of a gate to let the molecules pass through it
An image showing the opening process of a gate to let the molecules pass through it
An image showing the opening process of a gate to let the molecules pass through it
An image showing the opening process of a gate to let the molecules pass through it
An image showing the opening process of a gate to let the molecules pass through it
  • Because of favorable diffusion and electrical gradients, more Na+ ions image descriptionenter the cell than K+ ions image descriptionexit.
An image showing Na+ (sodium) ion diffusion through a channel of a neuron cell membrane which is anlarged
An image showing Na+ (sodium) ion diffusion through a channel of a neuron cell membrane which is anlarged
An image showing Na+ (sodium) ion diffusion through a channel of a neuron cell membrane which is anlarged
An image showing Na+ (sodium) ion diffusion through a channel of a neuron cell membrane which is anlarged
An image showing Na+ (sodium) ion diffusion through a channel of a neuron cell membrane which is anlarged
An image showing Na+ (sodium) ion diffusion through a channel of a neuron cell membrane which is anlarged
An image showing Na+ (sodium) ion diffusion through a channel of a neuron cell membrane which is anlarged
An image showing Na+ (sodium) ion diffusion through a channel of a neuron cell membrane which is anlarged
An image showing Na+ (sodium) ion diffusion through a channel of a neuron cell membrane which is anlarged
An image showing K+ (potassium) ion diffusion through a channel of a neuron cell membrane which is anlarged
An image showing K+ (potassium) ion diffusion through a channel of a neuron cell membrane which is anlarged
An image showing K+ (potassium) ion diffusion through a channel of a neuron cell membrane which is anlarged
An image showing K+ (potassium) ion diffusion through a channel of a neuron cell membrane which is anlarged
An image showing K+ (potassium) ion diffusion through a channel of a neuron cell membrane which is anlarged
An image showing K+ (potassium) ion diffusion through a channel of a neuron cell membrane which is anlarged
An image showing K+ (potassium) ion diffusion through a channel of a neuron cell membrane which is anlarged
An image showing K+ (potassium) ion diffusion through a channel of a neuron cell membrane which is anlarged
An image showing K+ (potassium) ion diffusion through a channel of a neuron cell membrane which is anlarged
An image showing K+ (potassium) ion diffusion through a channel of a neuron cell membrane which is anlarged
  • A gain in positive ions inside the postsynaptic neuron causes it to image descriptiondepolarize (excitatory postsynaptic potential or EPSP).
An image showing the depolarization chart on the board, the cell membrane of a neuron cell is magnified
An image showing the depolarization chart on the board, the cell membrane of a neuron cell is magnified
An image showing the depolarization chart on the board, the cell membrane of a neuron cell is magnified
An image showing the depolarization chart on the board, the cell membrane of a neuron cell is magnified
An image showing the depolarization chart on the board, the cell membrane of a neuron cell is magnified
An image showing the depolarization chart on the board, the cell membrane of a neuron cell is magnified
An image showing the depolarization chart on the board, the cell membrane of a neuron cell is magnified
An image showing the depolarization chart on the board, the cell membrane of a neuron cell is magnified
  • The amount of depolarization is graded (variable) and depends on how many ACh molecules bind to the postsyaptic receptors and how many ions are exchanged.