Signaling mechanism peripheral nervous system

CNTF is expressed in glial cells within the central and peripheral nervous system. CNTF lacks a signal sequence and is not secreted by the classical secretory pathway, but is thought to convey its cytoprotective effects after release from adult glial cells by some mechanism induced by injury [3,5]. 

Adenosine 5 -triphosphate is an excitatory neurotransmitter in the CNS and the peripheral nervous system (PNS). ATP acts via ionotropic P2X receptors (Chapter 3) and also acts through metabotropic G protein-linked P2Y receptors. With respect to P2Y receptors 1-13 that have been distinguished, uridine 5 -triphosphate (UTP) and ATP bind to P2Y2 and P2Y4 and ATP also binds to P2Y11. The signalling mechanism involves Gaq-mediated cytosolic Ca2+ elevation. 

Acetylcholine is the endogenous neurotransmitter at cholinergic synapses and neuroeffector junctions in the central and peripheral nervous systems. The actions of acetylcholine are mediated through nicotinic and muscarinic cholinergic receptors, which transduce signals via distinct mechanisms. 

The regulation of the total peripheral resistance also involves the complex interactions of several mechanisms. These include baroreflexes and sympathetic nervous system activity response to neurohumoral substances and endothelial factors myogenic adjustments at the cellular level, some mediated by ion channels and events at the cellular membrane and intercellular events mediated by receptors and mechanisms for signal transduction. As examples of some of these mechanisms, there are two major neural reflex arcs (Fig. 1). Baroreflexes are derived from high-pressure barorecep-tors in the aortic arch and carotid sinus and low-pressure cardiopulmonary baroreceptors in ventricles and atria. These receptors respond to stretch (high pressure) or... 

In response to these activation stimuli, action potentials are conducted towards the central nervous system, where they may elicit reflex responses in respiratory pattern (e.g. rapid, shallow breathing), or alterations in pulmonary mechanics. As the action potentials, on their way to the central nervous system, pass the terminal ramifications of axon dendrites, antidromic conduction occurs and signals are propagated toward peripheral nerve... 

Figure 7.1. Vomiting Mechanisms. The afferent nervous (peripheral and central) and humoral inputs converge to the medullary area. Here the signals are examined and integrated and may lead to emesis (expulsion of gastrointestinal contents). The efferent output involves respiratory muscles, visceral organs, cardiovascular system, visceral and cutaneous vasculature. The endogenous factors are released into...

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