This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cell Physiology and Intercellular Connections, Subject name: Physiology
In extreme cold, which is not a mechanism of thermogenesis - 
Select and explain. 
A. Shivering, B. Increased secretion of epinephrine, C. Increased thyroxine, D. Piloerection
D: Piloerection
Answer: D: Piloerection 
Explanation: Ans. is 'd' i.e., Piloerectiono Thermogenesis means increased production of heat.o Piloerection is a mechanism for decreased heat loss (not for increased production of heat, i.e. thermogenesis). Further, piloerection is important for animals, but not for human.Mechanisms activated by cold (mechanisms of heat gain)Increased head productionDecreased heat losso Shiveringo Cutaneous vasoconstrictiono Hvperphagiao Reduced surface areaCurling upo Increased secretion of catecholamineso Piloerection It is important for animals witho Increased secretion of thyroxinefur or feathers but not for humano Exercise (Increased voluntary muscle activity) o Non-shivering thermogenesis