. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. HEAT REGULATION IN MAMMALS AND BIRDS 241 UNITS ItO 120 100 GRADIENT AT 80 faO 40 20 300 200 100. ATc = K-I»E 300 200 100 -120 -'00 -80 -60 -?0 0 20 I f\ TEnPEKMTUP T. FIGURE 3. Diagram of a thermoregulated system consisting of an electric fan inside a rigid insulator (insert). The full drawn lines represent the relative energy input necessary to main- tain the "body temperature" of 40° C. for different air temperatures, assuming a minimum (basal) energy level of 100 and a maximum insulation of 1, 2, and 4 units. Th
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. HEAT REGULATION IN MAMMALS AND BIRDS 241 UNITS ItO 120 100 GRADIENT AT 80 faO 40 20 300 200 100. ATc = K-I»E 300 200 100 -120 -'00 -80 -60 -?0 0 20 I f\ TEnPEKMTUP T. FIGURE 3. Diagram of a thermoregulated system consisting of an electric fan inside a rigid insulator (insert). The full drawn lines represent the relative energy input necessary to main- tain the "body temperature" of 40° C. for different air temperatures, assuming a minimum (basal) energy level of 100 and a maximum insulation of 1, 2, and 4 units. The thermoregulation is assumed to proceed in two steps: first an increase in insulation until it reaches maximum at the critical temperature, then an increase in the metabolic rate. At the critical temperature the body- to-air gradient is called the critical gradient &TC. At constant insulation the system cools pro- portionally to the gradient and it will be seen from the figure that the critical gradient is propor- tional to both insulation and metabolic rate according to the equation given. stirred by setting up slight convection currents in the spirometer. The accuracy obtained by this well established open circuit technique was ample for our purpose. For cooling the tropical animals, a deep freeze box was used with an insulated wooden lid furnished with fan and heater. In this was placed the respiration cham- ber as already described. The rate of oxygen consumption (arctic animals) or CCX production (tropical animals) relative to temperature was plotted for each individual animal, the basal level taken from the plot, and the data recalculated and replotted relative to the basal level which is called 100 (Figs. 2-11). In the large series of arctic experiments performed by Hock, both CCX produc- tion and oxygen consumption were determined. The RQ was rarely outside — all through the temperature ranges, and hence either oxygen consumption or CO, production can
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
