Neurotransmitters of autonomic nervous system

The two most common neurotransmitters released by neurons of the ANS are acetylcholine (Ach) and norepinephrine (NE). Several distinguishing features of these neurotransmitters are summarized in Table 9.3. Nerve fibers that release acetylcholine are referred to as cholinergic fibers and include all preganglionic fibers of the ANS — sympathetic and parasympathetic systems all postganglionic fibers of the parasympathetic system and sympathetic postganglionic 

Site of All preganglionic neurons of Most sympathetic postganglionic neurons Adrenal medulla (80% of 

Release autonomic nervous system all postganglionic neurons of parasympathetic system some sympatheticpostganglionicneurons innervating sweat glands (alpha motor neurons innervating skeletal muscle)b adrenal medulla (20% of secretion) secretion) 

Receptor Nicotinic, muscarinic (cholinergic) (Xj, a2, P (adrenergic) %, a2, Pj, p2 (adrenergic) 

Termination Enzymatic degradation by Reuptake into nerve terminals diffusion Metabolic transformation by 

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Table 9.3 Distinguishing Features of Neurotransmitters of Autonomic Nervous System...

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