Part of the AUTONOMIC NERVOUS SYSTEM. It consists of scattered collections of grey matter known as ganglia, united by an irregular network of nerve-?bres; those portions where the ganglia are placed most closely and where the network of ?bres is especially dense being known as plexuses. The chief part of the sympathetic system consists of two ganglionated cords that run through the neck, chest, and abdomen, lying close in front of the spine. In conjunction with the other part of the autonomic nervous system – the parasympathetic – this part controls many of the body’s involuntary activities involving glands, organs and other tissues. (For further details, see NERVOUS SYSTEM.)... sympathetic nervous system
A division of the autonomic or involuntary nervous system that works in general opposition to the parasympathetic division (q.v.). Many of the sympathetic functions are local, specific, and involve secretion of acetylcholine, like any other of your normal nerves...stimulating or suppressing a specific muscle, gland, or whatever. A certain number of these nerves, however, unlike any others in the body, secrete epinephrine (adrenalin) and norepinephrine (noradrenalin). These are called adrenergic. Since the adrenal medulla also secretes the same substances into the bloodstream as hormones, all the muscles or glands that are affected by the adrenergic sympathetic nerves also react in toto to the epinephrine secreted into the blood. This forms the basis for a potentially lifesaving emergency fight or flight response and is meant for short, drastic activities. A chronic excess of the adrenergic response, however, is a major cause of stress-and a major contributor to many types of chronic disease. The more you use a particular nerve pathway or induce a particular group of functions, the more blood, fuel storage, and mitochondria are produced to strengthen that group of actions. Using adrenergic energy excessively gives literal dominance to those things that are stimulated or suppressed, and the effects of adrenalin stress linger in the body after the adrenalin is long gone. Since one of the first subjective symptoms of subclinical malnutrition, metabolic imbalances, and environmental pollution is irritability of the central nervous system, hypersympathetic function acts as an intermediate between poor diet, pollution, and disease.... sympathetic
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