Pflügers Archiv

, Volume 353, Issue 3, pp 191–199 | Cite as

Static and dynamic activity of warm receptors in Boa constrictor

  • H. Hensel


Afferent impulses from multi- and single-fiber preparations of the trigeminal nerve inBoa constrictor were recorded during exactly controlled thermal stimulation of the receptive field in the labial region. At constant temperatures in the range between 18 and 37°C, multi-fiber preparations showed a continuous discharge with a maximum around 30°C. Dynamic warming caused a high increase of the discharge, whereas dynamic cooling led to a complete inhibition. No cold-sensitive fibers have been found. Mechanical stimulation elicited large spikes from specific mechanoreceptors.

Single-fiber preparations from labial warm receptors did not respond to mechanical stimulation. Their discharge was always regular at constant temperatures. The average frequency of a warm receptor population was zero at about 18°C, reached a maximum of 13 sec−1 at 30°C and fell again to zero at 37°C. In addition, a few warm receptors increased their static discharge with temperature up to 36°C, the highest frequency being 38 sec−1. Stepwise warming by ΔT=+5°C caused a marked overshoot in frequency, after which the discharge usually fell to a minimum and then rose again to a new static level. Stepwise cooling by ΔT=−5°C led to a transient inhibition of activity followed by an increase until the new static level was reached. In the first group of warm receptors the height of the dynamic overshoot varied with the adapting temperature, the largest average overshoot of 160 sec−1 occurring at an adapting temperature of 30°C. These receptors have their static maximum as well as their highest dynamic sensitivity in the temperature range of the natural tropical habitat of Boidae.

Key words

Warm Receptors Thermoreceptors Boa constrictor Boidae 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Barrett, R., Maderson, P. F. A., Meszler, R. M.: The pit organs of snakes. In: Biology of the reptilia, Vol. 2, Morphology B, ed. C. Gans, coed. Th. S. Parsons, pp. 277–314. London-New York: Academic Press 1970Google Scholar
  2. Bullock, T. H., Barrett, R.: Radiant heat reception in snakes. Commun. behav. Biol. Part A,1, 19–29 (1968)Google Scholar
  3. Gamow, R. I., Harris, J. F.: Infrared receptors of snakes. Sci. Amer.228, 94–100 (1973)Google Scholar
  4. Goris, R. C., Terashima, S.: Central response to infrared stimulation of the pit receptors in a Crotaline snake,Trimeresurus flavoviridis. J. exp. Biol.58, 59–76 (1973)Google Scholar
  5. Harris, J. F., Gamow, R. I.: Snake infrared receptors: Thermal or photochemical mechanism? Science172, 1252–1253 (1971)Google Scholar
  6. Harris, J. F., Gamow, R. I.: An analysis of heat receptors by means of microwave radiation. ISA-BM72336, 187–190 (1972)Google Scholar
  7. Hartline, P. H.: Responses of tectal units to infrared stimuli in rattlesnakes. Soc. Neurosci. Program Abstr. p. 74 (1972)Google Scholar
  8. Hensel, H.: Properties of warm receptors in Boa constrictor. Naturwissenschaften61, 369 (1974a)Google Scholar
  9. Hensel, H.: Thermoreceptors. Ann. Rev. Physiol.36, 233–249 (1974b)Google Scholar
  10. Hensel, H., Huopaniemi, T.: Static and dynamic properties of warm fibres in the infraorbital nerve. Pflügers Arch.309, 1–10 (1969)Google Scholar
  11. Hensel, H., Kenshalo, D. R.: Warm receptors in the nasal region of cats. J. Physiol. (Lond.)204, 99–112 (1969)Google Scholar
  12. Otto, J.: Das Grubenorgan, ein biologisches System zur Abbildung von Infrarotstrahlern. Kybernetik10, 103–106 (1972)Google Scholar
  13. Ros, M.: Die Lippengruben der Pythonen als Temperaturorgane. Jena. Z. Naturw. (N. F.)70, 1–32 (1935)Google Scholar
  14. Terashima, S., Goris, R. C., Katsuki, Y.: Structure of warm fiber terminals in the pit membrane of vipers. J. Ultrastruct. Res.31, 494–506 (1970)Google Scholar
  15. Warren, J. W., Proske, U.: Infrared receptors in the facial pits of the Australian python Morelia spilotes. Science159, 439–441 (1968)Google Scholar

Copyright information

© Springer-Verlag 1975

Authors and Affiliations

  • H. Hensel
    • 1
  1. 1.Institut für Physiologie der Universität MarburgMarburgGermany

Personalised recommendations