题目

Born into a farmer’s family, life was not easy when I was a kid. We were so poor that we often did not know where our next meal was coming from. I had to sell cabbages at the marketplace to support my family. A storyteller once came to the marketplace, and I went to listen to him. My mother was unhappy with me for forgetting my job. But that night, while she was making clothes for us under the weak light of an oil lamp, I couldn't help retelling stories I'd heard that day. She listened impatiently at first, since in her eyes professional（职业的） storytellers were smooth-talking人体内激素分泌量过多或不足都会对机体有害，体内有一系列机制维持激素在血液中含量的相对稳定。下图表示下丘脑神经分泌细胞、垂体细胞、甲状腺细胞及它们分泌的激素之间的关系：据图回答有关问题： （1）激素A是_____________。 （2）当体内缺乏____________元素时，将导致激素C的合成受阻。 （3）人遭遇危险而情绪紧张时血液中激素c的含量将会________________，这是由于激素A、B的含量______________所致。 （4）如果激素c的合成量过多时，激素A、B含量的变化趋势是　　　　　　　　　 ，这是一种________________调节机制。