I. Definition endocrine(内分泌) endocrine gland(内分泌腺) endocrine system(内分泌系统) hormone(激素) Discussion Which concept/ concepts are not clear to you?Ⅰ.Definition • endocrine（内分泌 ） • endocrine gland （内分泌腺） • endocrine system （内分泌系统） • hormone（激素） • Discussion： Which concept／concepts are not clear to you?