Humoral signals

The relationship between central and peripheral oscillators is different in flies and mammals. In mammals, these oscillators form a hierarchy in which the central oscillator, which resides in the suprachiasmatic nucleus (SCN), functions as a master clock that is entrained by photic signals from the eye, and in turn drives subservient peripheral oscillators via humoral signals (Moore et al 1995, Yamazaki et al 2000, Kramer et al 2001, Cheng et al 2002). In contrast, both central and peripheral oscillators operate autonomously and are directly entrainable by light in Drosophila (Plautz et al 1997), thus obviating the need for a hierarchical system. Our results support the concept of independent oscillators in flies since central (sUN ) oscillators are not necessary for olfaction rhythms and local oscillators in antennae appear to be sufficient. 

Although they are often diagrammed as straight lines or wires, communications systems are much more complex, and often display characteristics of a transmission line (Figure 4.4.2). Transmission lines have resistance, capacity, and inertia elements that slow and degrade a signal. This is true for both neural and humoral signals. 

Cholecystokinin (CCK) is produced in the intestine and the brain. It appears to be an important mediator of anxiety. It also stimulates vasopressin secretion and slows gastric emptying. In addition, it is an important humoral satiety signal (appetite control). Various antagonists have been developed and are currently being investigated with regard to their therapeutic potential. 

Serum Ig levels Cellular immunity Anti-microbial activity Humoral immunity Apoptosis Cell signaling... 

Figure 7.1. Vomiting Mechanisms. The afferent nervous (peripheral and central) and humoral inputs converge to the medullary area. Here the signals are examined and integrated and may lead to emesis (expulsion of gastrointestinal contents). The efferent output involves respiratory muscles, visceral organs, cardiovascular system, visceral and cutaneous vasculature. The endogenous factors are released into...

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