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The effects of temperature change on the mammalian muscle spindle
Başlık:
The effects of temperature change on the mammalian muscle spindle
Yazar:
Weir, Andrew Ian, author.
ISBN:
9780438057340
Yazar Ek Girişi:
Fiziksel Tanımlama:
1 electronic resource (127 pages)
Genel Not:
Source: Dissertation Abstracts International, Volume: 76-08C.
Advisors: Ian Boyd.
Özet:
A study was performed on the effects of temperature change on the afferent discharge of a mammalian muscle spindle. Literature was reviewed concerning 1. The structure of a muscle spindle and the characteristics of its discharge observed in the afferent nerve. 2 The effect of temperature on muscle receptors. 3. The natural limits of muscle temperature. Results showed: A) For the Primary sensory ending. (I) The discharge frequency of the Primary sensory ending rose linearly with extension over the range 3 mm. to 7 mm. extension from resting muscle length. (II) Below 3 mm. extension a threshold effect was described and this was related to the extension of the spiral of the Primary ending. (III) The frequency of discharge at constant length was increased by increasing temperature, and this effect was further increased by stretching the muscle. Quantitatively there was a change in the resting discharge frequency of 3.5% of the impulse frequency at 35°C. per degree Centigrade change. This increased to 12% after an extension of 5 mm. (IV) Fatigue and heat contractive effects were described. (V) Two hypotheses were suggested to explain how the effect of temperature change could be significant in the realm of muscle control. (VI) The Dynamic Index was defined and shown to increase with extension velocity while being independent of extension length except for small extensions at low temperatures. (VII) The Dynamic Index was shown to increase with temperature over the range 20°C, to 35°C. (VIII) The Dynamic Index was shown to be directly proportional to the Dynamic Sensitivity (a parameter defined as the peak frequency during a ramp stretch minus the final fully adapted frequency at the end of the stretch). This relationship was confirmed over a wide range of extension lengths, velocities and temperatures. B) For the Secondary sensory ending. (I) The discharge frequency of a Secondary sensory ending was shown to increase with linear extension from the resting length to 5 mm. extension. (II) The 'cold response' described by Lippold et al 1960 was confirmed as the discharge from a Secondary ending at low extension. (III) The threshold of discharge of the Secondary ending was shown to depend on both the temperature and the linear extension of the preparation. In the proposed normal muscle temperature range of 34°C. to 41°C. the deefferented preparation was shown to be silent when not under stretch. (IV) The impulse frequency of discharge per mm. extension above threshold (i.e. the Static Sensitivity) was shown to increase with temperature. (V) A fatigue response similar to that of the Primary ending was not demonstrated. (VI) The large increases in discharge frequency - (4.2% of frequency of discharge at 35°C. per degree Centigrade temperature change at 5 mm. extension) - were considered with respect to the wider field of muscle control. (VII) The Dynamic Index of the Secondary ending was shown to be lower than that of the Primary ending in comparable conditions of temperature, extension length and velocity. Numerically, however, it was shown that the Dynamic Index of a Secondary ending in conditions of high temperature, large extension length, and high velocity can approach that of the Primary ending. (VIII) The Dynamic Index of the Secondary ending was shown to increase with rising temperature. (IX) The constant linear relationship between the Dynamic Index and Dynamic Sensitivity was confirmed for the Secondary ending. It was concluded that, in view of the detailed results outlined above, the central nervous system must have a mechanism for compensating for temperature change in active muscles, or that the accuracy required of afferent input to the extrapyramidal motor system has been greatly overestimated.
Notlar:
School code: 0547
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Yer Numarası | Demirbaş Numarası | Shelf Location | Lokasyon / Statüsü / İade Tarihi |
---|---|---|---|
XX(684593.1) | 684593-1001 | Proquest E-Tez Koleksiyonu | Arıyor... |
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