Receptor mechano

An interneuron together with a sensory afferent and motor efferent form a polysynaptic reflex (Figure 2.2) this comprises the initial stage of information input (sensory afferent), the processing/computing an appropriate response (interneurons) and the execution of a behavioural response (motor efferent). The simplest reflexes in the nervous system are monosynaptic reflexes, such as the familiar tendon (knee) jerk, these do not involve an interneuron. The sensory afferent activated by the mechano-receptor (the tap of the patellar hammer) forms a synapse with the motor efferent in the spinal cord, which then causes the skeletal muscle to contract and the crossed leg to jerk forward. With a synaptic delay of 1 millisecond (ms), the time between input and output increases with the number of synapses introduced into the circuit. As an... 

P americana is one of just a few species of insects in which both peripheral and central olfactory processing have been studied. In contrast to many short-lived lepidopterans, in which the male antenna is highly specialized for sex pheromone reception, the antennae of male cockroaches contain numerous food-responsive sensilla. In addition to olfactory sensilla, the antennae also house mechano-, hygro-and thermoreceptors, as well as contact chemoreceptors (Schaller, 1978 review Boeckh et al., 1984). Extensive ultrastructural and electrophysiological evidence has demonstrated that morphologically defined sensillum types house receptor cells of specific functional types (Sass, 1976, 1978, 1983 Schaller, 1978 Selzer, 1981, 1984 review Boeckh and Ernst, 1987). Boeckh and Ernst (1987) defined 25 types of cell according to their odor spectra, but of the 65 500 chemo- and mechanosensory sensilla on the antenna of adult male P. americana, an estimated 37 000 house cells that respond to periplanone-A and periplanone-B. 

The search for ion channels that respond to mechanical impulses has been pursued in a variety of organisms. Drosophila have sensory bristles used for detecting small air currents. These bristles respond to mechanical displacement in ways similar to those of hair cells displacement of a bristle in one direction leads to substantial transmembrane current. Strains of mutant fruit flies that show uncoordinated motion and clumsiness have been examined for their electrophysiological responses to displacement of the sensory bristles. In one set of strains, transmembrane currents were dramatically reduced. The mutated gene in these strains was found to encode a protein of 1619 amino acids, called NompC forno mechano receptor potential. 

Paoletti P, Ascher P (1994) Mechano.sensitivity of NMDA receptors in cultured mouse central neurons. Neuron 73 645-655. 

By their similitude with the receptor from living organisms these mechano-electrical systems, composed from polymer gels, open new possibilities of investigation of the artificial perception, with potential application in robotics or prosthesis. 

Wang T, Taylor EW, Reid SG, Milsom WK. Interactive effects of mechano- and chem-receptor inputs on cardio-respiratory outputs in the toad. Respir Physiol. Submitted. 

The pharmacological mechanism of action of capsaicin has been extensively reviewed [78]. In 1997, Julius and coworkers isolated and cloned the molecular target of capsaicin, a cellular transmembrane protein and a nonselective cation-permeable pore region (channel) named transient receptor potential vanilloid subtype 1 (TRPVl, also known as vanilloid receptor for its interaction with capsaicinoids) [79]. The TRPVl receptor is found in primary afferent polymodal C-fibers and A8-fibers. C-Fibers are responsible for the burning sensations, while A8-fibers are responsible for the temperature (cold and hot), pressure (mechano), and pain sensations. Both fibers are located in... 

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