Conditioned stimulus
Classical conditioning is a learning procedure in which a biologically potent stimulus paired with previously neutral stimulus. This pairing will cause a response that can be the same as the potent stimulus. This is done repeatedly for an organism to elicit a conditioned response to the previously neutral stimulus that was paired to the active stimulus. The dog salivates due to the idea that food is related to the sound of the bell.
The lysosomes are responsible for that
