you're using those raw materials

你的身体使用这些原料
to build other molecules but there are

合成其他分子
waste products of that process of

但是分解以及合成分子的过程中
breaking down and building back up molecules.

会有废物产生
A waste product of sugar metabolism is carbon dioxide,

糖代谢中的一种废物是二氧化碳
where it is the final form of carbon in the body is carbon dioxide.

碳在人体中的最终形式是二氧化碳
You get rid of that not in the kidney largely,

二氧化碳在肾脏排泄量不大
but mainly in the lung by breathing out CO2.

而主要是从肺中呼出二氧化碳的
The main product of nitrogen metabolism--

氮代谢的主要产物
and where does nitrogen come from?

氮来自哪里呢
It comes from proteins that we eat.

它来自我们所摄入的蛋白质
In the Western world, in developed worlds,

在西方发达世界中