. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 0 2 4 6 8 10 12 Time (sec) Figure 6. Response of TSR-5 (in xilu preparation) to imposed flexion, (a) and (b): the time courses of impulse discharges in the rapidly and slowly adapting stretch receptors, respectively. Inset: responses from the two types of stretch receptors. Lower trace, flexion amplitude (60° from horizontal). Time scale, I s. however, impulse frequencies of the TSR-5 were some- what increased (data not shown). Response of thoracic stretch receptors to stretch stimuli Both slowly and rapidly adapting impulse
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 0 2 4 6 8 10 12 Time (sec) Figure 6. Response of TSR-5 (in xilu preparation) to imposed flexion, (a) and (b): the time courses of impulse discharges in the rapidly and slowly adapting stretch receptors, respectively. Inset: responses from the two types of stretch receptors. Lower trace, flexion amplitude (60° from horizontal). Time scale, I s. however, impulse frequencies of the TSR-5 were some- what increased (data not shown). Response of thoracic stretch receptors to stretch stimuli Both slowly and rapidly adapting impulse discharges were evoked from each stretch receptor in the 3rd to 8th thoracic segments by an imposed stretch stimulus. In contrast, TSR-l in the most anterior segment is a simple stretch receptor and its response is only slowly adapting (not shown). To represent activities of the stretch receptors with both slowly and rapidly adapting cells, the records from TSR-2 are shown in Figure 8, and two kinds of impulse discharges differing in their frequency and am- plitude can be seen (Fig. 8A). One was derived from a slowly adapting receptor cell and showed a tonic impulse discharge that gradually adapted as long as the receptor muscle was stretched. In this particular receptor, the on- going tonic impulse discharges appeared before the stretch stimulus because we extended the receptor muscle slightly while securing the thoracic segment with insect pins to the cork platform in the experimental chamber. In this experiment, therefore, we took the initial length of the receptor muscle with the slight extension as its apparent zero length. When the receptor muscle was stretched in increments of mm (Fig. 8B), a notable phasic response occurred at an increment of mm from the relative zero length of the receptor muscle (Fig. 8B). This indicates that the cells showing a phasic response possess a higher threshold for a given length of stretch than cells showing a tonic response, an
Size: 1443px × 1731px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
