This area is always tender to the touch if the intestines are not functioning properly.

如果肠功能不正常的话，这个部位总是一按就痛。

《柯林斯英汉双解大词典》

The body is not functioning properly.

人感到非常的累，机体功能也不正常。

youdao

So this mouse's brain is, basically, not functioning properly.

因此，这老鼠的大脑，基本上不正常。

youdao

It's true that when you've got a corpse, you've got all the parts there, but clearly they're not functioning properly.

当你面对一具死尸时,肉体所有的部分的确都摆在那里,但它们显然无法正常运作

耶鲁公开课 - 死亡课程节选

If your brain is not functioning properly, and a drug can make it work better, then it makes sense to take the pill.

BBC: Joanna Moncrief