Thermoregulation is the control of the core temperature of the body. Thermoreceptors send information about a change in core temperature to the hypothalamus. The hypothalamus controls the core temperature by sending impulses to activate several physiological responses. Table 6.1 lists physiological responses to a decrease in core temperature. Complete Table 6.1 to explain how each response contributes to maintaining a core temperature within narrow limits. [Table 6.1] The Sitatunga deer, Tragelaphus spekii, and the Nile monitor lizard, Varanus niloticus, live in Africa. Fig. 6.1 shows a Sitatunga and Fig. 6.2 shows a Nile monitor. [Figure 6.1] [Figure 6.2] An investigation was carried out to measure the core temperature of the Sitatunga and the Nile monitor as the environmental temperature was increased. The results are shown in Fig. 6.3. [Figure 6.3]