Endocrine system definition

A second problem concerns delimiting the mechanisms of action which should be included in the definition, to exclude effects which are a secondary consequence of overt toxicity in other body systems. For example, disruption to the endocrine system caused by general metabolic disturbance, such as in severe liver damage, should not be grounds for calling a chemical an ED. 

The conventional definition of the endocrine system is the collection of ductless glands that secrete small amounts of hormones directly into the blood of vertebrates. The hormones are transported to other parts of the body where they have a profound effect on biological processes. Perhaps the best examples are the sex hormones oestrogen and testosterone, but there are many others. Hormones are also produced by invertebrates (e.g. moulting hormones) and even by plants (e.g. growth hormones). 

It proved difficult to definitively demonstrate CRH synthesis from immune cells, although numerous studies provided evidence this does happen (Aird et al., 1993 Ekman et al., 1993). Eventually it became clear that regulation of CRH synthesis and release in immune cells differs from that in hypothalamic neurons. While immune cells may synthesize and release much smaller concentrations of CRH and other neuroimmune peptides, and although their release may require de novo synthesis, an inherently slow process, the fact that immune cells release these hormones locally in the target area compensates for both of these factors to some extent. These data indicating site and tissue specific effects of CRH, sometimes even contradictory effects, point to the complex interrelationship betw een the nervous, endocrine and immune systems, an interaction that has yet to be deciphered completely. 

Myopathy is the term used broadly for affections of the skeletal musculature, in which the muscular symptoms in no way arise from disordered function of the central or peripheral nervous system. Within this definition are included, therefore, such widely differing conditions as the polymyositis syndrome, endocrine myopathies associated with thyroid gland disorders, and the muscular dystrophies. 

This is another evidence to conclude that delayed consequences are in direct relation to the damages inflicted on the central nervous system subcortical structures. No doubt, a definite limit of affection of subcortical structures exists, beyond which the course of intoxication will be confused. Under limit of affection one should understand not so much the intensity, but the time period during which the poisonous substances were applied intra-venal application, as compared to prolonged, for example skin resorption, has decreased effect in the formation of delayed neuro-endocrine toxicity. 

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