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Biomedical subjects

G A Shelton

Publications and source records attributed to G A Shelton.

4 recordsLinked to original sources
PubMed1975

The transmission of impulses in the ectodermal slow conduction system of the sea anemone Calliactis parasitica (Couch).

1. The SS 1 fatigues in response to repetitive electrical stimulation. This fatigue is manifested by an increased conduction delay and a decreased SS 1 pulse amplitude. 2. Continued repetitive stimulation leads to the failure of the system. Recovery may take many seconds. Narrow strips of column fail more rapidly than wide strips. 3. The increased conduction delay is explained in terms of a decrease in the population of spiking cells. 4. A computer model is described and analysed. It suggests that conduction between electrically coupled ectoderm cells could be the basis for the SS1. The SS 1 may have properties not so far experimentally demonstrated; for example, under certain conditions it could behave as a local system.

Animals↗
PubMed1975

Colonial conduction systems in the Anthozoa: Octocorallia.

1. The octocorals Alcyonium digitatum, Pennatula phosphorea and Virgularia mirabilis each have a through-conducting nerve net. The nerve net demonstrated electrophysiologically may well be the same as that previously shown by the use of histological techniques. 2. It exhibits both facilitation and defacilitation in the rate of conduction of pulses. 3. The distance of spread of nerve net activity is not limited by the number of stimuli applied. 4. The nerve net controls fast muscle contractions; the frequency of pulses is important in determining which muscles contract and in which sequence. 5. The nerve net is 'spontaneously' active. 6. A previously undescirbed slow system has been identified in Pennatula. It has many of the properties of slow systems in sea anemones and may well be ectodermal. It is suggested that multiple conduction systems are of common occurrence in the Anthozoa.

Animals↗