a computer, the brain uses dozens of chemical messages in its far-reaching influence. The messengers are called neuropeptides or neurotransmitters. They hook up the brain with the nervous system, endocrine system, and the immune system. The outcome is a web humming with information, touching the life of every cell. The brain is the most prolific gland in the body. Using its secretions in different combinations, the brain “writes” thousands of prescriptions to meet the body’s needs. Someone calls