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Biogenic amines are synthesised from only several types of amino acids and dependant on which amino acids are used in their formation depends on their classification. Biogenic amines that are derived from the amino acid tyrosine are classified as '''catecholamines''' and include the SMTs '''norepinephrine (NE)''' (noradrenaline), '''epinephrine (E)''' (adrenaline), '''melatonin''' and '''dopamine (DA)'''. Adrenergic neurons release norepinephrine. The biogenic amine that is dervied 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.   

Biogenic amines are synthesised from only several types of amino acids and dependant on which amino acids are used in their formation depends on their classification. Biogenic amines that are derived from the amino acid tyrosine are classified as '''catecholamines''' and include the SMTs '''norepinephrine (NE)''' (noradrenaline), '''epinephrine (E)''' (adrenaline), '''melatonin''' and '''dopamine (DA)'''. Adrenergic neurons release norepinephrine. The biogenic amine that is dervied 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.   

====Other SMTs====

====Other SMTs====

Other common SMTs include '''acetylcholine (ACh)''', '''ATP''' and '''nitric oxide (NO)'''. 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_%26_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 it's depolarisation threshold and generate an action potential.  

Other common SMTs include '''acetylcholine (ACh)''', '''ATP''' and '''nitric oxide (NO)'''. 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_%26_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 it's depolarisation threshold and generate an action potential. '''ACh''' has an effect on the post-synaptic membrane via '''nicotinic receptors''' which are ionotropic (see below).

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