Acetylcholine: Difference between revisions
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Acetylcholine, often abbreviated to Ach, is a [[Neurotransmitter|neurotransmitter found]] in the [[Autonomic nervous system|autonomic nervous system]]. It was first identified in 1914 by Henry Dale and confirmed as a neurotransmitter by Otto Loewi. In 1936 they both received a Nobel prize for their work in Medicine. | Acetylcholine, often abbreviated to Ach, is a [[Neurotransmitter|neurotransmitter found]] in the [[Autonomic nervous system|autonomic nervous system]] of both vertebrates and invertebrates. <ref>(Reece, Urry, Cain, Wasserman, Minorsky, Jackson. (2012) Campbell Biology , 9th Edition, San Francisco: Pearson Benjamin Cummings, Pages 1103-1104).</ref> It was first identified in 1914 by Henry Dale and confirmed as a neurotransmitter by Otto Loewi. In 1936 they both received a Nobel prize for their work in Medicine. | ||
= Chemical Structure = | |||
Ach is an [[Ester|ester]] of [[Acetic acid|acetic acid]] and [[Choline|choline]] and has a systemic name of 2-(acetyloxy)-N,N,N-trimethylethanaminium<ref>http://www.medic8.com/medicines/Acetylcholine.html</ref>. <br> | Ach is an [[Ester|ester]] of [[Acetic acid|acetic acid]] and [[Choline|choline]] and has a systemic name of 2-(acetyloxy)-N,N,N-trimethylethanaminium<ref>http://www.medic8.com/medicines/Acetylcholine.html</ref>. <br> | ||
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Acetylcholine is released and found in the [[Preganglionic neuron|preganglionic]] and [[Postganglionic neuron|postganglionic neurons]] of the [[Parasympathetic nervous system|parasympathetic nervous system]]. It is also present in the preganglionic neurons of the sympathetic nervous system. In these nervous systems Ach binds to two different types of receptors- the [[Nicotinic Ach receptor|nicotinic Ach receptor]] annd the [[Muscarinic Ach receptor|muscarinic Ach receptor]]. The nicotinic Ach receptor is a [[Ionotropic receptor|ionotropic receptor]] and can be atagonised by the poison [[Curare|curare]]. The muscarinic Ach receptor is a [[Metabotropic receptor|metabotropic receptor]] and is antagonised by the chemical compound [[Atropine|atropine]]. | Acetylcholine is released and found in the [[Preganglionic neuron|preganglionic]] and [[Postganglionic neuron|postganglionic neurons]] of the [[Parasympathetic nervous system|parasympathetic nervous system]]. It is also present in the preganglionic neurons of the sympathetic nervous system. In these nervous systems Ach binds to two different types of receptors- the [[Nicotinic Ach receptor|nicotinic Ach receptor]] annd the [[Muscarinic Ach receptor|muscarinic Ach receptor]]. The nicotinic Ach receptor is a [[Ionotropic receptor|ionotropic receptor]] and can be atagonised by the poison [[Curare|curare]]. The muscarinic Ach receptor is a [[Metabotropic receptor|metabotropic receptor]] and is antagonised by the chemical compound [[Atropine|atropine]]. | ||
=== References === | <br> | ||
= Signalling Pathways = | |||
Within Vertebrates, Acetylcholine is most commonly found in the [[Brain|brain]] and is indeed often considered the main excitatory [[Neurotransmitter|neurotransmitter]]. It is exceptionally diverse in that it is able to function via two different pathways. <br>Firstly via [[Ligand-gated ion channel|Ligand-Gated ion channels]] or ‘Ionotropic Receptors’, also used by neurotransmitters such as [[Glutamate|Glutamate]] and [[Glycine|Glycine]], which involve the use of Ionotropic Receptors. During this process, Acetylcholine is released from [[Presynaptic and postsynaptic neurons|presynaptic neurones within]] [[Vesicles|vesicles]], which diffuse across the [[Synapse|synapse]] towards the [[Presynaptic and postsynaptic neurons|postsynaptic neurone]]. On the surface of the postsynatpic neurone are complementary ionotropic receptor proteins, which receive the Acetylcholine. The binding of Acetylcholine to its ionotropic receptor causes the opening of Ligand-gated ion channels in the postsynaptic neurone and hence the release of Sodium ions (during an [[EPSP|EPSP]]) in turn causing the [[Action potential|action potential]] to be generated in the postsynaptic neurone.<br>Secondly Acetylcholine can be recieved by metabotropic receptors which are frequently found in the [[Heart|heart]]. Here the binding of Acetylcholine to its metabotropic receptor causes a series of changes within a signalling pathway, resulting in the opening of potassium channels in the muscle cell membrane. This has a [[Parasympathetic nervous system|parasympathetic]] effect on the heart rate. <ref>(Reece, Urry, Cain, Wasserman, Minorsky, Jackson. (2012) Campbell Biology , 9th Edition, San Francisco: Pearson Benjamin Cummings, Pages 1103-1104).</ref><br><br> | |||
=== References === | |||
<references /> | <references /> | ||
Revision as of 15:36, 27 November 2013
Acetylcholine, often abbreviated to Ach, is a neurotransmitter found in the autonomic nervous system of both vertebrates and invertebrates. [1] It was first identified in 1914 by Henry Dale and confirmed as a neurotransmitter by Otto Loewi. In 1936 they both received a Nobel prize for their work in Medicine.
Chemical Structure
Ach is an ester of acetic acid and choline and has a systemic name of 2-(acetyloxy)-N,N,N-trimethylethanaminium[2].
Acetylcholine is released and found in the preganglionic and postganglionic neurons of the parasympathetic nervous system. It is also present in the preganglionic neurons of the sympathetic nervous system. In these nervous systems Ach binds to two different types of receptors- the nicotinic Ach receptor annd the muscarinic Ach receptor. The nicotinic Ach receptor is a ionotropic receptor and can be atagonised by the poison curare. The muscarinic Ach receptor is a metabotropic receptor and is antagonised by the chemical compound atropine.
Signalling Pathways
Within Vertebrates, Acetylcholine is most commonly found in the brain and is indeed often considered the main excitatory neurotransmitter. It is exceptionally diverse in that it is able to function via two different pathways.
Firstly via Ligand-Gated ion channels or ‘Ionotropic Receptors’, also used by neurotransmitters such as Glutamate and Glycine, which involve the use of Ionotropic Receptors. During this process, Acetylcholine is released from presynaptic neurones within vesicles, which diffuse across the synapse towards the postsynaptic neurone. On the surface of the postsynatpic neurone are complementary ionotropic receptor proteins, which receive the Acetylcholine. The binding of Acetylcholine to its ionotropic receptor causes the opening of Ligand-gated ion channels in the postsynaptic neurone and hence the release of Sodium ions (during an EPSP) in turn causing the action potential to be generated in the postsynaptic neurone.
Secondly Acetylcholine can be recieved by metabotropic receptors which are frequently found in the heart. Here the binding of Acetylcholine to its metabotropic receptor causes a series of changes within a signalling pathway, resulting in the opening of potassium channels in the muscle cell membrane. This has a parasympathetic effect on the heart rate. [3]
References
- ↑ (Reece, Urry, Cain, Wasserman, Minorsky, Jackson. (2012) Campbell Biology , 9th Edition, San Francisco: Pearson Benjamin Cummings, Pages 1103-1104).
- ↑ http://www.medic8.com/medicines/Acetylcholine.html
- ↑ (Reece, Urry, Cain, Wasserman, Minorsky, Jackson. (2012) Campbell Biology , 9th Edition, San Francisco: Pearson Benjamin Cummings, Pages 1103-1104).