The hormone thyroxin, for example, is secreted by an endocrine gland — your thyroid — and it needs to be distributed throughout the entire body so that it can stimulate the metabolism in all of your cells.
例,
甲状腺
由内分
腺分
——你的甲状腺——它需要分布
身体中,以便它可以刺
所有细胞的新陈代谢。