The arrival of a nerve impulse causes the release of neurotransmitter

What causes the presynaptic membrane to release neurotransmitter? Neurotransmitter is released when a nerve impulse arrives at the axon terminal. The presynaptic membrane contains voltage-gated calcium channels. When a nerve impulse depolarizes the axon terminal, it causes these channels to open (see Figure 44.13). Because Ca2+ concentra

The acetylcholine receptor-mediated channel is normally closed.

When ACh binds at specific sites on the receptor, the channel opens, allowing Na+ to enter the postsynaptic cell.

Acetylcholinesterase breaks down ACh, causing the receptor-mediated channel to close.

The acetylcholine receptor-mediated channel is normally closed.

When ACh binds at specific sites on the receptor, the channel opens, allowing Na+ to enter the postsynaptic cell.

Acetylcholinesterase breaks down ACh, causing the receptor-mediated channel to close.

Nerve Impulse And Acetylcholine

ACh receptor

Inside of cell

Postsynaptic cell depolarizes

44.14 The Acetylcholine Receptor Is a Chemically Gated Channel The motor end plate contains acetylcholine (ACh) receptors, which are chemically gated ion channels. When one of these receptors binds ACh, its channel pore opens, and Na+ ions move into the postsynaptic cell, depolarizing its plasma membrane. An enzyme called acetylcholinesterase breaks down ACh in the synapse, closing the channel; the breakdown products are then resynthesized into more ACh.

ACh receptor

Inside of cell

Postsynaptic cell depolarizes tion is greater outside the cell than inside the cell, Ca enters the axon terminal near the synaptic vesicles.

The increase in Ca2+ inside the axon terminal causes the vesicles containing acetylcholine to fuse with the presynap-tic membrane and empty their contents into the synaptic cleft. The acetylcholine molecules diffuse within the cleft, and some bind to acetylcholine receptors on the motor end plate.

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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Responses

  • dennis
    What are the causes for nerve receptors?
    7 years ago
  • ANDREA
    What enters a depolarizes a cell?
    7 years ago
  • SOPHIA
    How Ach is released from the presynaptic membrane?
    7 years ago
  • Cara
    Which ion causes the release of neurotransmitter from the axon terminal?
    6 years ago
  • gloriana
    What arrives at the axon terminal and causes the release of acetylcholine?
    6 years ago
  • Medhanie
    What is released when the nerve impulse arrives at the axon terminal?
    6 years ago
  • amethyst
    When a nerve arrives, it causes the release of a?
    6 years ago
  • jessica schroder
    Which ion causes neurotransmitter vesicles to fuse with the axon?
    6 years ago

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