Brain area that controls voluntary movement grow substantially during first year of life whereas the frontal part involved in complex thinking spurts around ages 6 and 10 and in early adolescence. Somatic system: sensory organs and muscles; engaged in sensing and voluntary movement. Autonomic system: helps involuntary regulation of arousal and the emotions. Parasympathetic system: slow arousal and maintain bodily functioning. Endocrine system: collection of glands intricately involved in bodily functions through the release of hormones (communicates with entire nervous system) Midbrain: contains fibers that connect the hindbrain and upper brain regions. Shares with hindbrain the reticular activating system-influences arousal states such as waking and sleeping. Midbrain and hindbrain are sometimes referred to as the brain stem. Forebrain: two cerebral hemispheres connected by the corpus callosum. Sensory processing, motor control, and higher mental functioning; info processing, learning, and memory. Thalamus: processing and relaying info between the cerebral hemispheres and other parts of the cns.