The Adequate Stimulus for Shivering.

Abstract

On the basis of Hensel''s recent account of the thermal sense organs, it may be postulated that the adequate stimulus for shivering is a combination of the rates at which cold sensitive end-organs are discharged, the no. stimulated, and the thermal state of the center. This postulate was tested by using a standard rate of room cooling and exposing varying areas of the subject''s body. In some expts., subjects drank cold water to lower deep body temp, before the start of room cooling. Skin temp., deep body temp., O2 uptake, and finger blood flow were measured by conventional methods. Heat loss was measured with Hatfield Turner discs. Shivering was reported by a hand-operated signal. In 4 subjects studied, the sequence of events with a standard rate of room cooling of 0.6[degree]C/ min. from 25[degree]C was: skin cooling, reduced blood flow, shivering, and increased O2 uptake. The position of reduced deep body temp, in this sequence was not definite, but lowered deep body temp, increased the tendency to shiver. At no time did shivering reach a level to maintain total body temp. The onset of shivering was related to the regions of the body exposed; covering the thorax delayed its onset longer than covering the legs. The geometric areas exposed were comparable, a difference existing in the no. of cold spots/sq. cm.