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Acetylcholine Receptors

  • Embedded in the membrane of the postsynaptic neuron are image descriptionreceptors for the neurotransmitter, acetylcholine (or ACh).
An image showing the Acetylcholine Receptor consists of presynaptic cholinergic neuron acting on ACh postsynaptic receptor
An image showing the Acetylcholine Receptor consists of presynaptic cholinergic neuron acting on postsynaptic ACh receptor, the postsynaptic membrane is magnified
An image showing the Acetylcholine Receptor consists of presynaptic cholinergic neuron acting on ACh postsynaptic receptor with labels for (Presynaptic neuron and Postsynaptic membrane), the postsynaptic membrane is magnified
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  • Two forms of ACh receptors occur in the central nervous system. The most common is called nicotinic type.
  • The term nicotinic is applied to these receptors because they can be stimulated by the drug, nicotine. The second type of ACh receptor, the muscarine type, differs in structure and mechanism of action and will not be discussed.
  • Nicotinic receptors are composed of five (5) polypeptide subunits, which together form a water-filled ion channel in the lipid bilayer.
  • Normally, the image descriptiongates are closed and ions are prevented from passing through the channel.
  • Two of the receptor’s subunits have binding sites for ACh molecules. When ACh image descriptionoccupies both sites.
  • The gated subunits change shape (conformation) and the channel image descriptionopens.
  • Nicotinic ACh receptors are also known as chemical-gated or ligand-gated channels. Ligand is used because the term refers to one molecule binding to another (larger) molecule.
  • While it is open, sodium (Na+ ) and potassium (K+ ) ions image descriptiondiffuse through the channel. The exchange of ions changes the membrane potential of postsynaptic neuron.

Overview:

Test yourself image image showing the Acetylcholine Receptor consists of presynaptic cholinergic neuron acting on ACh postsynaptic receptor, (1. Presynaptic neuron 2. Postsynaptic neuron 3. ACh receptors ) are numbered without answers, the postsynaptic membrane is magnified
Test yourself image image showing the Acetylcholine Receptor consists of presynaptic cholinergic neuron acting on ACh postsynaptic receptor, (1. Presynaptic neuron 2. Postsynaptic neuron 3. ACh receptors ) are numbered with answers below, the postsynaptic membrane is magnified
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