Heat production and heat loss Basal metabolic rate is controlled by hypothalamus by varying the level of circulating thyroxine (E 腺素) Increased muscle sensitivity(shivering) e By varying the volume of blood flowing to skin's surface(100 fold By vaporization(exocrine sweating)Heat production and heat loss •Basal metabolic rate is controlled by hypothalamus, by varying the level of circulating thyroxine （肾上 腺素） •Increased muscle sensitivity (shivering) •By varying the volume of blood flowing to skin’s surface (>100 fold) •By vaporization (exocrine sweating)