What are the stimuli, receptors, and control centers in the brain? Also, what is the effector?

The answer to this question could take up a whole book. An effector is something that initiates a process, e.g., a biochemical cascade such as apoptosis. For the rest of your question, you can refer to some of the free Neuroscience text books online at NCBI (see links below). I've also included some good links for less-in-depth material.