Biologically dependent stimuli

Biologically dependent stimuli characteristically include analytes and biomacromolecules such as receptors, enzymes, glutathione, glucose, and metabolites that are over-produced in inflammation. 

Chemical cues hold considerable promise for manipulating behavior in vertebrates, provided we understand an animal s natural history, biology, and behavior well. However, the development of chemical attractants, stimulants, inhibitors, and repellents for vertebrates has progressed rather slowly for several reasons. First, chemical stimulus and behavior are not connected as rigidly as in insects, for example. Second, the same stimulus may elicit different behaviors, depending on the state of the recipient and the context. Third, chemical cues often are rather complex mixtures of compounds. Fourth, learning, especially early experience plays a major role in vertebrate, notably mammalian behavior. Finally, many behaviors are modulated by several sensory modalities so that chemical stimuli alone trigger only incomplete responses at best. 

The regulation of calcitonin synthesis and release from the parafollicular C cells of the thyroid gland is calcium dependent. Rising serum calcium is the principal stimulus responsible for calcitonin synthesis and release. Other hormones, such as glucagon, gastrin, and serotonin, also stimulate calcitonin release. Calcitonin has been isolated in tissues other than the parafollicular C cells (parathyroid, pancreas, thymus, adrenal), but it is not known whether this material is biologically active. 

The best way to test the viability of the platelets is to evaluate their response to a standard stimulus, such as thrombin. The biological endpoint, which is reached in a concentration dependent manner, is aggregation. 

VOien the response is quantal, its occurrence for any particular subject will depend upon the level of the stimulus. For this subject under constant environmental conditions, a common assumption is that there is a certain dose level below which the particular subject will not respond in a specified manner, and above which the subject will respond with certainty. This level is referred to as the subject s tolerance. Because of biological variability among subjects in the population, their tolerance levels will also vary. For quantal responses, it is therefore natural to consider the frequency distribution of tolerances over the population studied. If D represents the level of a particular stimulus, or dose, then the frequency distribution of tolerances, f(D), may be mathematically expressed as... 

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