The human nervous system is divided into the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS, in turn, is divided into the brain and the spinal cord, which lie in the cranial cavity of the skull and the vertebral canal, respectively. The CNS and the PNS, acting in concert, integrate sensory information and control motor and cognitive functions. Based on its functions, the CNS can be divided into three main functional components: the sensory system, the motor system, and homeostatic and higher brain functions. Cell signaling throughout the CNS occurs by means of neurotransmitters or ions of various kinds interacting at membrane bound receptors and ion channels that, in turn, send the signal through second messenger systems to different compartments of the cell. Malfunctions of the CNS can cause numerous diseases and disorders such as Alzheimer's and Parkinson's disease, multiple sclerosis (MS), anxiety, schizophrenia, and many others. Although many of these failures of the CNS appear to be age related, some occur already in a very early stage of development of the organism, or may even be genetically inherited. The prevention and treatment of neurological disorders represents one of the most difficult and challenging goals of modern medical research.