(a) Homeostasis in mammals involves negative feedback mechanisms. Outline how a negative feedback mechanism works. (b) [Figure 8.1] is a diagram summarising the role of the nervous and endocrine systems in the control of blood glucose concentration. With reference to Fig. 8.1, describe the role of the nervous system in the control of blood glucose concentration. (c) If the core temperature of the human body falls, the hypothalamus sends impulses to activate several physiological responses, some of which are listed below. For each one, state how it would help to bring the core temperature back to normal. vasoconstriction shivering increasing secretion of adrenaline