Your body doesnt know where your lungs, kidneys, heart etc. are. And your brain wouldnt either without the necropsies and impromtu surgeries that were done to figure all of that out.

Considering how of biology is just remembering the mapping to random names scientists came up with, I doubt it

But when you get past 40 the body starts sending you signals you can't ignore.

All parts of your body, except your brain apparently

"Knows" is a strong word, though they do have a sort of language: https://www.youtube.com/watch?v=TYPFenJQciw

Counterpoint

Brain: uh oh, the germs have arrived

Body: *starts getting warmer*

Brain: what are you doing?

Body: gettin hot

Brain: why are you getting hot?

Body: gonna kill germs

Brain: won't that kill us too?

Body: ¯\_(ツ)_/¯