Answer:
Hope this helps!
Explanation:
"When your body is injured in some way or something else is wrong, your nerves (cells that help your body send and receive information) send millions of messages to your brain about what's going on. Your brain then makes you feel pain." -Why Do I Have Pain? (for Kids) - Nemours KidsHealth
I didn't write that, but I gave credit to whoever did.
Biological structures like DNA, proteins and cells all depend on molecules. ... Neurotransmitters like epinephrine are pretty simple molecules, but without them our nervous system couldn't work. Oxygen, containing just two oxygen atoms, is a very simple molecule, and it is certainly essential to living things.
Active site is the answer, i hope this helps:)
