Non-synaptic transmission at autonomic neuroeffector junctions.
Non-synaptic transmission is characteristic of autonomic neuroeffector junctions. The structure of the autonomic neuromuscular junction is described. The essential features are that: the terminal portions of autonomic nerve fibers are varicose and mobile, transmitters being released 'en passage' from varying distances from the effector cells; while there is no structural post-junctional specialization on effector cells, receptors for neurotransmitters accumulate on cell membranes at close junctions; muscle effectors are bundles rather than single smooth muscle cells, that are connected by gap junctions which allow electrotonic spread of activity between cells. A multiplicity of transmitters are utilized by autonomic nerves, and cotransmission occurs often involving synergistic actions of the cotransmitters, although pre- and post-junctional neuromodulation of neurotransmitter release also take place. It is suggested that autonomic neural control of immune, epithelial and endothelial cells also involves non-synaptic transmission.
|Title:||Non-synaptic transmission at autonomic neuroeffector junctions.|
|Keywords:||Animals, Humans, Microscopy, Electron, Scanning, Neuroeffector Junction, Synaptic Transmission|
|UCL classification:||UCL > School of Life and Medical Sciences
UCL > School of Life and Medical Sciences > Faculty of Life Sciences
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