In aerobic respiration.there are stages in it.but I think you are looking for word "Krebs cycle"
Outer core is the answer - Appex
I'd use the library, the encyclopedia and the Internet.
Answer:
it is complicated but you add 1+1 and get two
Nicotine, once in the brain, will work specifically on nicotinic receptors in the brain. However, there is a common "addiction" pathway in the brain that pretty much all addictive substances go through.
