Autonomic nervous system features

A special feature of the iris is its autonomic innervation. Sympathetic activation widens the aperture of the iris whereas impulses from the parasympa thetic nervous system decrease the aperture size. Therefore adrenergic agonists and anticholinergic compounds both increase the aperture of the iris, i.e., cause mydriasis, and antiadrenergic and cholinergic agonists decrease it, i.e., cause miosis. The iris can thus be considered an excellent mirror reflecting the balance of the autonomic nervous system in the body. " ... 

Table 9.1 Distinguishing Features of Autonomic and Somatic Nervous Systems Autonomic nervous system Somatic nervous system...

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

Lewy body pathology is also the defining feature of several other, rarer diseases, such as Lewy body dysphagia and pure autonomic failure. In these diseases, Lewy bodies and neurites are largely limited to the enteric and peripheral nervous systems. In Parkinson s disease, Lewy body pathology is also present in the enteric and autonomic nervous systems. 

The autonomic nervous system consists of two functionally distinct parts that frequently exert antagonistic effects on their target organs. These are referred to as the sympathetic and the parasympathetic system, respectively. Figure 7.6 depicts some essential features. The parasympathetic system, for the most part, emerges from the central nervous system at the level of the medulla oblongata, which is the lowermost part of the brainl These neurons reach... 

Dysautonomias also range from mechanistically straightforward disorders in which altered autonomic function plays a primary pathophysiological role (e.g., pure autonomic failure), to conditions in which altered autonomic fimction worsens an independent pathophysiological state (e.g., cardiac failure), and to more mysterious disorders in which the involvement of the autonomic nervous system is less clear (e.g., chronic fatigue syndrome). Abnormalities of blood pressure control represent the common presenting cfinical features of the dysautonomias. In those involving... 

The definition of receptors as specific sites for drug action owes much to the work of John Newton Langley [ 1852-1925 ] and Paul Ehrlich [ 1854-1915 ]. Their separate work on the autonomic nervous system and toxins and chemotherapeutic agents led to the concept of a receptor that possesses both recognition and transduction components and of chemotherapeutic molecules possessing discrete molecular features subserving specific functions ... 

The mature adult peripheral nervous system is composed of the sensory and motor systems emanating from the spinal cord the autonomic nervous system, which is composed of both the sympathetic and parasympathetic systems and the enterie nervous system, which, due to its unique structural, chemical, and functional features, is presently considered to be separate from the autonomic nervous system even though it demonstrates profound interactions with the sympathetic and parasympathetic systems. 

Figure 6-1. Schematic diagram comparing some features of the parasympathetic and sympathetic divisions of the autonomic nervous system with the somatic motor system. Parasympathetic ganglia are not shown as discrete structures because most of them are diffusely distributed in the walls of the organs innervated. ACh, acetylcholine Epi, epinephrine NE, norepinephrine, D, dopamine N, nicotinic M, muscarinic a, p, alpha and beta adrenoceptors D, dopamine, receptors. (Reproduced, with permission, from Katzung BG [editor] Basic Clinical Pharmacology, 8th ed. McGraw-Hill, 2001.)...

Fig. 7.3 summarizes the anatomical features of the autonomic nervous system. This differs from the voluntary system (exemplified by the neuro-niuscular junction in Fig. 7.1) in that one extra control point exists for each fibre, namely an extra synapse (situated in a ganglion). In sympathetic fibres, these ganglia are not far from the spinal cord in parasympathetic fibres, the ganglia are near the end-organ, i.e. the one which the nerve is to influence. As... 

PEM is one of the most frequent cancer-associated syndromes. This complex disorder usually affects several areas of the CNS. Cerebellar and brain stem disorders, as well as limbic encephalitis, are the most common clinical presentations of PEM [31, 32], Focal involvement of the sensorimotor cortex has been described in a few cases [33], and PEM may manifest as epileptic seizures or epilepsia partialis continua [33, 34], or as extrapyramidal symptoms [35], Two-thirds of the patients are affected in both the CNS and the peripheral nervous system. The predominant feature in more than half of these is SN [32, 36], hence the commonly used term is PEM/SN. Autonomic dysfunction is common in PEM/SN patients [36], often presenting as gastrointestinal dysmotility [37]. 

Toxic action is complex, involving both stimulation and blockade of autonomic ganglia and skeletal muscle neuromuscular junctions, as well as direct effects on the central nervous system. Paralysis and vascular collapse are prominent features of acute poisoning, but death is usually due to respiratory paralysis, which may ensue promptly after the first symptoms of poisoning. Nicotine is not an inhibitor of cholinesterase enzyme. 

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