Synapse

From The School of Biomedical Sciences Wiki
(Difference between revisions)
Jump to: navigation, search
m
Line 1: Line 1:
The synapse is a the specific site where neuronal signals are transmitted from cell to cell. It is a structure where the electical signals of one [[Neuron|neuron]] are converted to chemical signals in order to transmit information from one [[Nerve cell|nerve cell]] to the next [[Nerve cell|nerve cell]](s). Postsynaptics cells are separated from presynaptic cells by a synaptic celft. The electrical potention in the presynaptic cell changes which causes the cell to release a neurotransmitter signalling molecule by exocytosis. The nurotransmitter moves across the synpatic cleft and triggers an electrical change in the postsynaptic cell.&nbsp;<ref>Bruce, A, Johnson, A, Lewis, J, Raff, M, Roberts, K and Walter, P (2008). Molecular Biology of the Cell. Fifth Edition. New York: Garland Science, Taylor &amp;amp; Francis Group, LLC. p682.</ref><br>
+
The synapse is a the specific site where neuronal signals are transmitted from cell to cell. It is a structure where the electical signals of one [[Neuron|neuron]] are converted to chemical signals in order to transmit information from one [[Nerve cell|nerve cell]] to the next [[Nerve cell|nerve cell]](s). Postsynaptic cells are separated from presynaptic cells by a synaptic cleft. The electrical potential in the presynaptic cell changes which causes the cell to release a neurotransmitter signalling molecule by exocytosis. The neurotransmitter moves across the synpatic cleft and triggers an electrical change in the postsynaptic cell.&nbsp;<ref>Bruce, A, Johnson, A, Lewis, J, Raff, M, Roberts, K and Walter, P (2008). Molecular Biology of the Cell. Fifth Edition. New York: Garland Science, Taylor &amp;amp;amp; Francis Group, LLC. p682.</ref><br>  
  
 
=== What happens at the Cholinergic Synapse?  ===
 
=== What happens at the Cholinergic Synapse?  ===
Line 5: Line 5:
 
Transmisson of an action potential across a synapse commonly involves [[Acetylcholine|Acetylcholine (Ach)]], a common neurocrine, neurones which secrete Ach are cholinergic.<ref>Silverthorn. D.U., 2007. Human Physiology an Integrated Approach. 4th Edition. San Francisco: Pearson Education Inc.</ref>  
 
Transmisson of an action potential across a synapse commonly involves [[Acetylcholine|Acetylcholine (Ach)]], a common neurocrine, neurones which secrete Ach are cholinergic.<ref>Silverthorn. D.U., 2007. Human Physiology an Integrated Approach. 4th Edition. San Francisco: Pearson Education Inc.</ref>  
 
<blockquote>
 
<blockquote>
*An action potential arrives at the pre-synaptic membrane causing voltage-gated [[Ca2+ pump|Ca]]<sup>[[Ca2+ pump|2+]] </sup>[[Ion channel|ion channels]] to open.&nbsp;Ca<sup>2+</sup>&nbsp;moves in through the [[Pre-synaptic memebrane|pre-synaptic memebrane]], down the chemical gradient.&nbsp;<br>
+
*An action potential arrives at the pre-synaptic membrane causing voltage-gated [[Ca2+ pump|Ca]]<sup>[[Ca2+ pump|2+]] </sup>[[Ion channel|ion channels]] to open.&nbsp;Ca<sup>2+</sup>&nbsp;moves in through the [[Pre-synaptic memebrane|pre-synaptic memebrane]], down the chemical gradient.&nbsp;<br>  
 
*This influx of Ca<sup>2+</sup> results in vesicles containing Ach to fuse with the pre-synaptic membrane, Ach is released into the synaptic cleft by [[Exocytosis|exocytosis]].&nbsp;  
 
*This influx of Ca<sup>2+</sup> results in vesicles containing Ach to fuse with the pre-synaptic membrane, Ach is released into the synaptic cleft by [[Exocytosis|exocytosis]].&nbsp;  
 
*Ach diffuses across the synaptic cleft and binds to specific neuroreceptor sites on the post-synaptic membrane.&nbsp;  
 
*Ach diffuses across the synaptic cleft and binds to specific neuroreceptor sites on the post-synaptic membrane.&nbsp;  
 
*Binding of Ach opens Na<sup>+</sup> ion channels on the [[Post-synaptic membrane|post-synaptic membrane]]. Na<sup>+</sup> ions diffuse across the post synaptic membrane into the post-synaptic neurone (down the chemical gradient). &nbsp;This causes depolarisation of the membrane which in-turn initiates an [[Action potential|action potential]].&nbsp;  
 
*Binding of Ach opens Na<sup>+</sup> ion channels on the [[Post-synaptic membrane|post-synaptic membrane]]. Na<sup>+</sup> ions diffuse across the post synaptic membrane into the post-synaptic neurone (down the chemical gradient). &nbsp;This causes depolarisation of the membrane which in-turn initiates an [[Action potential|action potential]].&nbsp;  
 
*The [[Enzyme|enzyme]] [[Acetylcholinesterase|acetylcholinesterase]] rapidly breaks down Ach in the [[Synaptic cleft|synaptic cleft]] (into [[Choline|choline]] and [[Acetyl-CoA|acetyl CoA]]) and the choline is transported back into the axon terminal where more Ach is synthesised&nbsp;<ref>Silverthorn. D.U., 2007. Human Physiology an Integrated Approach. 4th Edition. San Francisco: Pearson Education Inc.</ref>.&nbsp;<br>
 
*The [[Enzyme|enzyme]] [[Acetylcholinesterase|acetylcholinesterase]] rapidly breaks down Ach in the [[Synaptic cleft|synaptic cleft]] (into [[Choline|choline]] and [[Acetyl-CoA|acetyl CoA]]) and the choline is transported back into the axon terminal where more Ach is synthesised&nbsp;<ref>Silverthorn. D.U., 2007. Human Physiology an Integrated Approach. 4th Edition. San Francisco: Pearson Education Inc.</ref>.&nbsp;<br>
</blockquote>
+
</blockquote>  
 
=== References  ===
 
=== References  ===
  
 
<references />
 
<references />

Revision as of 20:01, 29 November 2015

The synapse is a the specific site where neuronal signals are transmitted from cell to cell. It is a structure where the electical signals of one neuron are converted to chemical signals in order to transmit information from one nerve cell to the next nerve cell(s). Postsynaptic cells are separated from presynaptic cells by a synaptic cleft. The electrical potential in the presynaptic cell changes which causes the cell to release a neurotransmitter signalling molecule by exocytosis. The neurotransmitter moves across the synpatic cleft and triggers an electrical change in the postsynaptic cell. [1]

What happens at the Cholinergic Synapse?

Transmisson of an action potential across a synapse commonly involves Acetylcholine (Ach), a common neurocrine, neurones which secrete Ach are cholinergic.[2]

  • An action potential arrives at the pre-synaptic membrane causing voltage-gated Ca2+ ion channels to open. Ca2+ moves in through the pre-synaptic memebrane, down the chemical gradient. 
  • This influx of Ca2+ results in vesicles containing Ach to fuse with the pre-synaptic membrane, Ach is released into the synaptic cleft by exocytosis
  • Ach diffuses across the synaptic cleft and binds to specific neuroreceptor sites on the post-synaptic membrane. 
  • Binding of Ach opens Na+ ion channels on the post-synaptic membrane. Na+ ions diffuse across the post synaptic membrane into the post-synaptic neurone (down the chemical gradient).  This causes depolarisation of the membrane which in-turn initiates an action potential
  • The enzyme acetylcholinesterase rapidly breaks down Ach in the synaptic cleft (into choline and acetyl CoA) and the choline is transported back into the axon terminal where more Ach is synthesised [3]

References

  1. Bruce, A, Johnson, A, Lewis, J, Raff, M, Roberts, K and Walter, P (2008). Molecular Biology of the Cell. Fifth Edition. New York: Garland Science, Taylor &amp;amp; Francis Group, LLC. p682.
  2. Silverthorn. D.U., 2007. Human Physiology an Integrated Approach. 4th Edition. San Francisco: Pearson Education Inc.
  3. Silverthorn. D.U., 2007. Human Physiology an Integrated Approach. 4th Edition. San Francisco: Pearson Education Inc.
Personal tools
Namespaces
Variants
Actions
Navigation
Toolbox