The digestive system, of course, is responsible for bringing in sort of fresh nutrients, fresh substrates for cellular metabolism, fresh quantities of amino acids, and nucleotides, and the things that we can't generate internally.

当然,还有消化系统,它主要负责将各种新鲜营养物摄入体内,为细胞代谢提供新的底物,如一批新的氨基酸,核苷酸,以及那些人体无法自行合成的东西

耶鲁公开课 - 生物医学工程探索课程节选