Autonomic nervous system cholinergic transmission

The answers arc 488-d, 489-h. (Katzang, pp 108-112, 1020.) Atropine blocks muscarinic cholinergic transmission in the brain and in the autonomic nervous system. The result is dry mouth, thirst, dry and hot skin, tachycardia, urinary retention, ataxia, restlessness, excitement, and hallucinations, followed by stupor, delirium, respiratory depression, coma, and death. 

Cholinergic neurotransmission ChEs terminate cholinergic transmission in the central nervous system (CNS), in NMJs and in the autonomic system (the parasympathetic system, somatic motor nerves and pre-ganglionic sympathetic nerves). A few sensory cells and the NMJ in nematodes also include ChEs. 

Evidence that acetylcholine is a chemical mediator of synaptic transmission elsewhere in the central nervous system is circumstantial but convincing. Acetylcholine is the transmitter substance from motor nerves, preganglionic autonomic fibres and the postganglionic fibres of the parasympathetic system to their respective effector cells. In all these fibres, the activity of choline acetyltransferase (choline acetylase), the enzyme responsible for the synthesis of acetylcholine, is high. Conversely, its activity is negligibly low in sensory nerve fibres and transmission from these fibres is demonstrably non-cholinergic in nature . It is reasonable, therefore, to... 

The basic structure of a synapse and the mechanism of cholinergic transmission are shown in Fig. 6.1. Within the cholinergic system, there are several different types of synapses which lead to different functions within both the autonomic and voluntary nervous systems. Shortly after the discovery by Otto Loewi in 1921 (Box 6.2) of ACh, it was found that there were two classes of synapses, termed muscarinic and... 

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