Peripheral sense organs

Mode of Action. DDT and its analogues specifically affect the peripheral sense organs of insects and produce violent trains of afferent impulses that result in hyperactivity, convulsions, and paralysis. Death results from metaboHc exhaustion and the production of an endogenous neurotoxin. The very high lipophilic nature of these compounds faciUtates absorption through the insect cuticle and penetration to the nerve tissue. The specific site of action is thought to be the sodium channels of the axon, through inhibition of Ca " ATPase. 

Before investigating two more detailed examples of potential misuse, it is necessary first to describe something of the structure of the human nervous system. This is divided into the central nervous system (brain and spinal cord) and the peripheral nervous system.46 Information from peripheral sense organs is received via afferent pathways and processed within the central nervous system. Output from the central nervous system is sent via efferent pathways to the somatic nervous system (muscles) and to the autonomic nervous system (heart, gut, glands, etc.). 

Hansen A. and Zeiske E. (1998). The peripheral olfactory organ of the zebrafish, Danio rerio an ultrastructural study. Chem Senses 23, 39-48. 

Babel, J., Bischoff, A. and Spoendlin, H. Ultrastructure of the peripheral nervous system and sense organs. In Atlas of Normal and Pathologic Anatomy. St Louis Mosby, 1970, pp. 1-171. 

Vijverberg, H.P.M., G.S.F. Ruigt, and J.V.D. Bercken. 1982. Structure-related effects of pyrethroid insecticides on the lateral-line sense organ and on peripheral nerves of the clawed frog, Xenopus laevis. Pestic. Biochem. Physiol. 18 315-324. 

Neurotoxicity can be defined as any adverse effect on the structure or function of the nervous system related to exposure to a chemical substance (US-EPA 1998, OECD 2004c). According to the TGD (EC 2003), neurotoxicity can be defined as the induction by a chemical of adverse effects in the central or peripheral nervous system, or in sense organs and a substance is neurotoxic if it induces a reproducible lesion in the nervous system or a reproducible pattern of neural dysfunction. ... 

Morphological (structural) changes in the central or peripheral nervous system or in special sense organs... 

The functional unit of the central nervous system (CNS) is the neuron, and most neuropharmacological agents have the neuron as their primary site of action. CNS neurons are capable of transmitting information to and receiving information from other neurons and peripheral end organs, such as muscle cells, glandular cells, and specialized receptors, for example, those involved with proprioception, temperature sensing, and so on. 

Another method employed rather frequently by neuropharmacologists involves measurement of transmission in sensory systems by the so-called evoked potential technique. A sense organ, e.g. the eye or the ear, is stimulated by a light flash or a loudspeaker click, and an afferent volley of nerve impulses is produced. This volley travels first through peripheral sensory nerve fibers and then through the afferent systems in the CNS to reach finally the so-called projection area of the cerebral cortex. 

Butyronitrile showed moderate to high toxicity on test animals. It is an acute toxicant by all rentes inhalation, ingestion, and absorption throngh skin. The target organs are the liver, kidney, central nervous system, lungs, and sense organs, as well as the peripheral nerve. Its toxicity is on the same order as that of propionitrile its inhalation toxicity is... 

The vestibular system is named for its position within the vestibule of the temporal bone of the skuU. It is located in the inner ear along with the auditory sense. The vestibular system has both central and peripheral components. This chapter deals with the mechanical sensory function of the peripheral end organ and its abdity to measure Hnear and angular inertial motion of the skuU over the frequency ranges encountered in normal activities. The transduction process used to convert the mechanical signals into neural ones is also described. 

General functions of the skin are outlined in Table 1. These functions include containment of tissues and organs, multifaceted protections, environmental sensing, and body temperature regulation. Some skin functions are inextricably entwined. For instance, containment and the barrier functions are to some extent inseparable. Active sweating is accompanied by increased peripheral blood flow, which in turn is tied in with greater nourishment of the cells of the skin as needed to promote their proliferation, differentiation, and specialization. 

A common reason for diuretic use is for reduction of peripheral or pulmonary edema that has accumulated as a result of cardiac, renal, or vascular diseases that reduce blood delivery to the kidney. This reduction is sensed as insufficient effective arterial blood volume and leads to salt and water retention and edema formation. Judicious use of diuretics can mobilize this interstitial edema without significant reductions in plasma volume. However, excessive diuretic therapy may lead to further compromise of the effective arterial blood volume with reduction in perfusion of vital organs. Therefore, the use of diuretics to mobilize edema requires careful monitoring of the patient s hemodynamic status and an understanding of the pathophysiology of the underlying illness. 

Prolonged TCE exposure has been associated with impairment of peripheral nervous system function, persistent neuritis and temporary loss of tactile sense and paralysis of the fingers after direct solvent contact. Chromosomal effects have been reported in those involved in the use of TCE for degreasing and symptoms of systemic lupus erythematosis have been reported after chronic TCE exposure. In addition, organic dementia has been noted after occupational exposure to TCE and there have been some reports of an association between exposure and scleroderma, an autoimmune disease. 

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