Chemical sensory systems

The function of a sensory system is to select suitable modalities from the multitude presented by the environment, and translate them into corresponding modalities of sensory information that are then projected and processed into the various parts and finally submitted to the central processing-unit, the brain. A working hypothesis of the mechanism by which the taste system senses chemical compounds is that macromolecules that are... 

Tucker D. (1971). Non-olfactory responses from nasal cavity Jacobson s Organ and trigeminal system. In Handbook of Sensory Physiology Chemical Senses, 1. Olfaction (Biedler L., ed.). Springer, Berlin, pp. 151-181. 

As with many macrosmatic mammals, rodents have two separate chemosensory systems, the main olfactory system (MOS) and accessory olfactory system (AOS), which respond to social odors. Importantly, these sensory systems differ not only in their peripheral morphology and central projections, but also in the types of chemosignals that they process (Meredith 1991). Sensory neurons of the MOS, which are located in the main olfactory epithelium and project to the main olfactory bulbs, process volatile chemicals and can detect odors at a distance. In contrast, sensory neurons of the AOS, which are located in the vomeronasal organs (VNO) and project to the accessory olfactory bulbs, primarily process large, non-volatile chemicals and require contact for stimulation (Meredith 1991). 

Olfaction, once thought to be a primitive sense, is now recognized as an elaborate sensory system that deploys a large family of odorant receptors to analyse the chemical environment. Interactions between these receptors and their diverse natural binding molecules (ligands) translate the world of odors into a neural code. Humans have about 350 odorant receptors. Rodents have more than a thousand. 

Jakubas, W. J. and Mason, J. R. (1991). Role of avian trigeminal sensory system in detecting coniferyl benzoate, a plant allelochemical. Journal of Chemical Ecology 17, 2213-2221. 

The Neurophysiology Sensory Evoked Potentials test guideline (OPPTS 870.6855) is designed to detect and characterize changes in the sensory aspects of nervous system function that result from exposure to chemical substances. The techniques involve neurophysiological measurements from adult animals and are sensitive to changes in the function of auditory, somatosensory (body sensation), and visual sensory systems. 

Ferveur J. F., Cobb M. and Jallon J. M. (1989) Complex chemical messages in Drosophila. In Neurobiology of Sensory Systems, eds R. N. Singh and N. J. Strausfeld. Plenum Publishing Corporation. 

Selection of a comprehensive testing battery to record the rate of AChE inhibition is a crucial point. In addition to the estimation of AChE activity, other functions (e.g., sensory systems, reflexes, neuromotor development, locomotion, gait, reactivity to medication) require close monitoring to achieve chemical safety to OPs. In the case of children and workers exposed to very low doses of OPs, other tests should indirectly include parameters like learning, memory loss, social behavior, and reproductive behavior. To integrate behavioral data into the context... 

In this paper the term taste will refer to all the chemical sensory systems of the oral cavity and their sensations. These sensory systems are intimately involved in the selection of food items and in the regulation of food intake. As we shall see, there are a variety of different taste systems attuned to different chemical aspects of food. These taste systems perform an exact and elaborate analysis of the chemical constituents in the food we eat. 

Vertebrates possess three primary chemosensory systems gustation ( taste ), trigeminal, and olfaction ( smell ) but only one of these, the olfactory system, mediates responses to pheromones. Chemicals that stimulate the olfactory system are known as odorants and comprise one type of biological cue (any entity that stimulates a sensory system). Bouquets of odorants that can be discriminated as specific entities are termed odors. The olfactory system contains olfactory receptor neurons (ORNs) that comprise cranial nerve I and project directly to the forebrain. ORNs are now known to express only one to a few olfactory receptor proteins ( receptors ), which means that the chemoreceptive range of each neuron can be very narrow. The olfactory system also has several subcomponents including the vomeronasal organ, which is described below. 

How do our sensory systems work How are the initial stimuli detected How are these initial biochemical events transformed into perceptions and experiences We have previously encountered systems that sense and respond to chemical signals—namely, receptors that bind to growth factors and hormones. Our knowledge of these receptors and their associated signal-transduction pathways provides us with concepts and tools for unraveling some of the workings of sensory systems. For example, 7TM receptors (seven-transmembrane receptors, Section 15.1) play key roles in olfaction,... 

Like taste, touch is a combination of sensory systems that are expressed in a common organ—in this case, the skin. The detection of pressure and the detection of temperature are two key components. Amiloride-sensitive sodium channels, homologous to those of taste, appear to play a role. Other systems are responsible for detecting painful stimuli such as high temperature, acid, or certain specific chemicals. Although our understanding of this sensory system is not as advanced as that of the other sensory systems, recent work has revealed a fascinating relation between pain and taste sensation, a relation well known to anyone who has eaten "spicy" food. 

Butenandt A et al (1959) N-Acetyl tyramine, its isolation from Bombyx cocoons and its chemical and biological properties. Arch Biochem Biophys 83 76-83 Cayirlioglu P et al (2008) Hybrid neurons in a microRNA mutant are putative evolutionary intermediates in insect C02 sensory system. Science 319 1256-1260 Clyne PJ et al (1999) A novel family of divergent seven-transmembrane proteins candidate odorant receptors in Drosophila. Neuron 22 327-338... 

The purpose of the present study was to identify those volatile compounds which significantly contribute to the seasoning-like note of fenugreek using the approach of sensory directed chemical analysts. Gas chromatography in combination with olfactometry and mass spectrometry have been used as key steps of this approach (18,19). The formation of flavor impact compound(s) was studied in model systems using the quantification technique Isotope Dilution Assay (20, 21) The mechanistic study was based on a hypothetical pathway proposed for the formation of sotolone via thermally induced oxidative deamination of HIL (10). 

The sensory system of any animal has presumably evolved under sources of selection generated by its environment. In an aquatic environment, for example, one expects animals to be able to sense fluid dynamics, since chemical cues important for survival are necessarily embedded in these movements (Mellon 2007). Not surprisingly then, aquatic crustaceans possess multiple fluid-flow detectors, chemoreceptors, and even bimodal chemo-mechanoreceptors (Hallberg and Skog, Chap. 6). A wealth of literature exists on all of these sensory structures and the... 

Possible solutions - Crustacean species employ various reproductive strategies in terms of the temporal relationship between gonad maturation, mating, and spawning, and these reproductive stages are coordinated with the molt cycle in a variety of ways (reviewed by Raviv et al. 2008). Can chemical cues be one of the inputs to the female sensory system that regulate any of these stages of a reproductive cycle ... 

Nature uses chemical signalling in sensory systems snch as taste and smell. The most important means for information processing in nature is based on information exchange between DNA and RNA our brain use signals relying on the behaviour of ions, etc. This... 

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