Neurotransmitters - Anatomy & Physiology - Revision history

Fiorecastro at 14:14, 6 January 2023

2023-01-06T14:14:13Z

Bara at 10:38, 4 November 2013

2013-11-04T10:38:20Z

ElzaTriegaardt: /* Biogenic Amines */

2013-11-03T13:09:57Z

Biogenic Amines

Bara at 19:49, 26 October 2012

2012-10-26T19:49:06Z

Bara at 11:33, 3 July 2012

2012-07-03T11:33:20Z

Bara: /* Small-Molecule Neurotransmitters */

2011-11-11T16:14:05Z

Small-Molecule Neurotransmitters

Bara at 16:11, 11 November 2011

2011-11-11T16:11:36Z

Show changes

Bara at 16:02, 11 November 2011

2011-11-11T16:02:27Z

Bara at 15:58, 11 November 2011

2011-11-11T15:58:50Z

Bara at 15:43, 11 November 2011

2011-11-11T15:43:25Z

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-{{OpenPagesTop}}
 ==Introduction==
 [[File:Synapse diag1.svg|thumb|right|250px|Synapse diagram - click image for image key]]
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 {{review}}
-{{OpenPages}}
+==Webinars==
 [[Category:A&P Done]]
 [[Category:Nervous System - Anatomy & Physiology]]

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 :If a β<sub>2</sub> receptor is bound this will result in hyperpolarisation of the cell which will cause dilation of the bronchioles of the lung.
 <br><br>
-'''Dopamine''' is involved in motivation as well as love and addiction. It is effectively a 'reward system' for the brain. Dopamine also affects the way in which the basal ganglia of the brain affect our movements and a shortage of dopamine can result in diseases such as Parkinson's. Dopamine is the primary neuroendocrine regulato r of [[Lactation - Endocrine Control - Anatomy & Physiology|'''prolactin''']] from the anterior [[Pituitary Gland - Anatomy & Physiology|pituitary gland]]. It is thus often called prolactin-inhibiting hormone in reproduction. Dopamine produced by the [[Hypothalamus - Anatomy & Physiology|hypothalamus]] is secreted via the hypothalamo-hypophysal blood vessels which supply the pituitary gland. Secretion of prolactin via lactotrope cells within the pituitary is inhibited by dopamine.
+'''Dopamine''' is involved in motivation as well as love and addiction. It is effectively a 'reward system' for the brain. Dopamine also affects the way in which the basal ganglia of the brain affect our movements and a shortage of dopamine can result in diseases such as Parkinson's. Dopamine is the primary neuroendocrine regulator of [[Lactation - Endocrine Control - Anatomy & Physiology|'''prolactin''']] from the anterior [[Pituitary Gland - Anatomy & Physiology|pituitary gland]]. It is thus often called prolactin-inhibiting hormone in reproduction. Dopamine produced by the [[Hypothalamus - Anatomy & Physiology|hypothalamus]] is secreted via the hypothalamo-hypophysal blood vessels which supply the pituitary gland. Secretion of prolactin via lactotrope cells within the pituitary is inhibited by dopamine.
 <br><br>
 '''Serotonin''' is involved in emotions, mood, sexuality, consciousness, sleep and thermoregulation. Serotonin is utilised by the central nervous system and the gastro-intestinal system. Serotonin has also been linked to mechanisms controlling pulmonary and cerebral vascular vasoconstriction.

@@ Line 37: / Line 37: @@
 :If a β<sub>2</sub> receptor is bound this will result in hyperpolarisation of the cell which will cause dilation of the bronchioles of the lung.
 <br><br>
-'''Dopamine''' is involved in motivation as well as love and addiction. It is effectively a 'reward system' for the brain. Dopamine also affects the way in which the basal ganglia of the brain affect our movements and a shortage of dopamine can result in diseases such as Parkinson's. Dopamine is the primary neuroendocrine regulator of [[Lactation - Endocrine Control - Anatomy & Physiology|'''prolactin''']] from the anterior [[Pituitary Gland - Anatomy & Physiology|pituitary gland]]. Dopamine produced by the [[Hypothalamus - Anatomy & Physiology|hypothalamus]] is secreted via the hypothalamo-hypophysal blood vessels which supply the pituitary gland. Secretion of prolactin via lactotrope cells within the pituitary is inhibited by dopamine.
+'''Dopamine''' is involved in motivation as well as love and addiction. It is effectively a 'reward system' for the brain. Dopamine also affects the way in which the basal ganglia of the brain affect our movements and a shortage of dopamine can result in diseases such as Parkinson's. Dopamine is the primary neuroendocrine regulato r of [[Lactation - Endocrine Control - Anatomy & Physiology|'''prolactin''']] from the anterior [[Pituitary Gland - Anatomy & Physiology|pituitary gland]]. It is thus often called prolactin-inhibiting hormone in reproduction. Dopamine produced by the [[Hypothalamus - Anatomy & Physiology|hypothalamus]] is secreted via the hypothalamo-hypophysal blood vessels which supply the pituitary gland. Secretion of prolactin via lactotrope cells within the pituitary is inhibited by dopamine.
 <br><br>
 '''Serotonin''' is involved in emotions, mood, sexuality, consciousness, sleep and thermoregulation. Serotonin is utilised by the central nervous system and the gastro-intestinal system. Serotonin has also been linked to mechanisms controlling pulmonary and cerebral vascular vasoconstriction.

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 ==Introduction==
 [[File:Synapse diag1.svg|thumb|right|250px|Synapse diagram - click image for image key]]
 '''Neurotransmitters''' are chemicals that are used to relay, amplify and modulate signals between [[Neurons - Anatomy & Physiology|neurones]] and cells. They can be classified into two main groups; '''small-molecule transmitters (SMT)''' and '''neuropeptides'''.

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 ==Introduction==
 [[File:Synapse diag1.svg|thumb|right|250px|Synapse diagram - click image for image key]]
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 {{review}}
 [[Category:A&P Done]]
 [[Category:Nervous System - Anatomy & Physiology]]

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 </gallery>
-====Other SMTs====
+===Other SMTs===
 Other common SMTs include acetylcholine, ATP and nitric oxide.
 '''Acetylcholine (ACh)''' is the most common '''excitatory''' neurotransmitter in the '''peripheral nervous system'''. Cholinergic neurons release ACh and for example, are found in the [[Muscles - Anatomy & Physiology#Neurogenic Contraction|neuromuscular junction]]. When ACh is released, it facilitates the opening of sodium channels within the post-synaptic membrane allowing sodium ions to enter the membrane and causing depolarisation. Therefore ACh makes it easier for the cell to reach its depolarisation threshold and generate an action potential. ACh has an effect on the post-synaptic membrane in skeletal muscle via '''nicotinic receptors''', which are ionotropic (see below). ACh also exerts an effect on smooth muscle via the parasympathetic nervous system via '''muscarinic receptors''', which are metabotropic (see below).
 '''Adenosine triphosphate (ATP)''', as well as having many important '''intracellular functions''', is an important neurotransmitter and also has an '''autocrine''' and '''paracrine''' function. ATP belongs to the '''purines''' SMT group. All synaptic vesicles released by the terminal membrane of a nerve contain ATP as well as other neurotransmitters, although ATP can only function as a neurotransmitter in its own right if the post-synaptic terminal membrane contains ATP receptors. These ATP receptors are referred to as '''purinergic receptors'''. A pre-synaptic nerve terminal or terminal membrane never releases multiple types of SMT in addition to ATP, although it is common that neuropeptides are released in addition to ATP and SMTs. Other SMTs within the purine group include '''Guanosine triphosphate (GTP)''' and their derivatives.
-Although '''nitric oxide (NO)''' is a neurotransmitter, its characteristics differ from those discussed above. NO relies on calcium ion activation of the enzyme '''nitric oxide synthase (NOS)''' which is found throughout the nervous system and is the enzyme that is responsible for catalysing NO from the amino acid '''L-arginine'''. NO has a very short half-life and is highly reactive. It is able to pass easily through lipid membranes. What makes NO differ from the SMTs above is that is can be released in all directions rather than pre-synaptically as per the classical SMTs. Therefore NO is able to act as a signalling pathway for the post-synaptic neuron to affect the pre-synpatic neuron.
+Although '''nitric oxide (NO)''' is a neurotransmitter, its characteristics differ from those discussed above. NO relies on calcium ion activation of the enzyme '''nitric oxide synthase (NOS)''' which is found throughout the nervous system and is the enzyme that is responsible for catalysing NO from the amino acid '''L-arginine'''. NO has a very short half-life and is highly reactive. It is able to pass easily through lipid membranes. What makes NO differ from the SMTs above is that is can be released in all directions rather than pre-synaptically as per the classical SMTs. Therefore NO is able to act as a signalling pathway for the post-synaptic neuron to affect the pre-synpatic neuron. Nitrous oxide is involved in enlargement of the genital organs leading to erection.
 <gallery widths="150px" perrow="3">

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 </gallery>
-====Biogenic Amines====
+===Biogenic Amines===
 Biogenic amines are synthesised from only several types of amino acids. Which amino acids are used in their formation depends on their classification.
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 The biogenic amine that is derived from the amino acid '''tryptophane''' is called '''serotonin (5-HT)''' whilst the SMT derived from '''histidine''' is called '''histamine (HA)'''. Serotonergic neurons release serotonin. Whilst these SMTs are primarily of importance in the central nervous system, norepinephrine is predominantly found in the peripheral nervous system.
-'''Epinephrine''' is produced by the adrenal glands. It is primarily involved in an overall activation of the sympathetic nervous system and is involved in the management of stress. '''Norepinephrine''' is also produced by adrenal glands and is involved in the initiation and maintainance of consciousness within the sympathetic nervous system. Both types of neurotransmitter utilise α or β receptors and are metabotropic. If an α<sub>1</sub> adrenergic receptor is bound this will result in depolarisation of the cell and vasoconstriction of the skin and viscera. If a β<sub>1</sub> receptor is bound this will also result in cellular depolarisation and an increase in heart rate and contractility. If a β<sub>2</sub> receptor is bound this will result in hyperpolarisation of the cell which will cause dilation of the bronchioles of the lung.
+'''Epinephrine''' is produced by the adrenal glands. It is primarily involved in an overall activation of the sympathetic nervous system and is involved in the management of stress. '''Norepinephrine''' is also produced by adrenal glands and is involved in the initiation and maintainance of consciousness within the sympathetic nervous system. Both types of neurotransmitter utilise α or β receptors and are metabotropic.
-<br />
+:If an α<sub>1</sub> adrenergic receptor is bound this will result in depolarisation of the cell and vasoconstriction of the skin and viscera.
-<br />
+:If a β<sub>1</sub> receptor is bound this will also result in cellular depolarisation and an increase in heart rate and contractility.
-'''Dopamine''' is involved in motivation as well as love and addiction. It is effectively a 'reward system' for the brain. Dopamine also affects the way in which the basal ganglia of the brain affect our movements and a shortage of dopamine can result in diseases such as Parkinson's. Dopamine is the primary neuroendocrine regulator of [[Lactation_-_Endocrine_Control_-_Anatomy_%26_Physiology|'''prolactin''']] from the anterior pituitary gland. Dopamine produced by the hypothalamus is secreted via the hypothalamo-hypophysal blood vessels which supply the pituitary gland. Secretion of prolactin via lactotrope cells within the pituitary is inhibited by dopamine.
+:If a β<sub>2</sub> receptor is bound this will result in hyperpolarisation of the cell which will cause dilation of the bronchioles of the lung.
-<br />
-<br />
+'''Dopamine''' is involved in motivation as well as love and addiction. It is effectively a 'reward system' for the brain. Dopamine also affects the way in which the basal ganglia of the brain affect our movements and a shortage of dopamine can result in diseases such as Parkinson's. Dopamine is the primary neuroendocrine regulator of [[Lactation - Endocrine Control - Anatomy & Physiology|'''prolactin''']] from the anterior [[Pituitary Gland - Anatomy & Physiology|pituitary gland]]. Dopamine produced by the [[hypothalamus]] is secreted via the hypothalamo-hypophysal blood vessels which supply the pituitary gland. Secretion of prolactin via lactotrope cells within the pituitary is inhibited by dopamine.
-'''Serotonin''' is involved in emotions, mood, sexuality, consciousness, sleep and thermoregulation. Serotonin it utilised by the central nervous system and the gastro-intestinal system. Serotonin has also been linked to mechanisms controlling pulmonary and cerebral vascular vasoconstriction.
-<br />
+'''Serotonin''' is involved in emotions, mood, sexuality, consciousness, sleep and thermoregulation. Serotonin is utilised by the central nervous system and the gastro-intestinal system. Serotonin has also been linked to mechanisms controlling pulmonary and cerebral vascular vasoconstriction.
-<br />
-'''Melatonin''' is responsible for the regulation of onset of sleep and also for seasonal changes in the body such as winter weight gain and mating seasons. '''Histamine''' release results in increased gastric secretions, dilation of capillaries, constriction of bronchial smooth muscle and decreased blood pressure.
+'''Melatonin''' is responsible for the regulation of onset of sleep and also for seasonal changes in the body such as winter weight gain and mating seasons.
 <gallery widths="150px" perrow="3">

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 Neuropeptides are constructed of around 3 - 40 amino acid molecules that are synthesised within the cell body and are then transported to along the axon to the nerve terminal within vesicles running along microtubules. Neuropeptides are broken down by extracellular enzymes called '''peptidases''' once the neurotransmitter has been released. A small proportion of neuropeptides can bind to postsynaptic receptors in the nerve terminal membrane and can be taken up by endocytosis, although the degree of recycling of neuropeptides is lower than that of SMTs.
-==Types of neurotransmitter==
+==Small-Molecule Neurotransmitters==
 There are two major sub-groups of SMTs; '''amino acids''' and '''biogenic amines'''. All SMTs play an important role within the central nervous system with the exception of acetylcholine and norepinephrine which both are important within the peripheral nervous system.
-====Amino Acids====
+===Amino Acids===
 Amino acid '''glutamate''' is the most common '''excitatory''' SMT in the [[Nervous and Special Senses - Anatomy & Physiology#Central Nervous System (CNS)|central nervous system]] whilst '''gamma-aminobutyric acid (GABA)''' is the most common '''inhibitory''' SMT. Other amino acid SMTs include '''aspartate''' and '''glycine'''.
 When '''glutamate''' is released it facilitates the opening of sodium channels within the post-synaptic membrane allowing sodium ions to enter the membrane and causing depolarisation. Therefore '''glutamate''' makes it easier for the cell to reach its depolarisation threshold and generate an action potential. Due to this, '''Glutamate''' is classified as an excitatory neurotransmitter.
-<br />
-<br />
+'''Glycine''' is present in the spinal cord and is crucial for limb movement; in particular the motor function associated with limb reflexes. When both '''glycine''' and '''GABA''' are released they result in the opening of chloride ion channels within the post synaptic membrane resulting in the membrane becoming hyperpolarised. The cytosolic side of the membrane becomes more negative. Therefore both neurotransmitters make it more difficult for the cell to reach its depolarisation threshold to generate an action potential, thus classed as inhibitory.
 <gallery widths="150px" perrow="3">