The brain and the spinal cord make up the central nervous system, which receives signals from the peripheral nervous systems (the nerves in the body), interprets them and sends out instructions for motor activity -- all in less than a second. Each part of the brain has a specific function, some of which are still unknown to scientists.
The cerebrum is the wrinkled upper half of the brain, what is normally thought of when people think "brain." The deep wrinkles, called sulci, increase the surface area so more information can be processed. The cerebrum is divided into two hemispheres, and each hemisphere has four lobes: frontal, parietal, temporal and occipital.
Lobes of the Cerebrum
The frontal lobe, behind the forehead, controls thinking, planning, judgment and movement. The parietal lobe, on the top of the head, interprets sensory information from the nerves regarding taste, smell and touch. The occipital lobe in the back of the head processes visual information. The temporal lobe, on the sides near the temples, processes sensory information from taste, smell and sound, and many memories are stored there as well.
The cerebellum is located in the back of the head below the occipital lobe. It combines sensory information to help coordinate movement -- it is also the part of the brain that helps you pass a field sobriety test from law enforcement by enabling you to touch your nose with your eyes closed and walk a straight line heel to toe.
The brain stem includes the midbrain, the pons and the medulla oblongata. The brain stem is very important to life, regulating heart rate, blood pressure, body temperature and sleeping. Also, any nerve impulse traveling to the brain from the spinal cord must first pass through the brain stem.
Just above the brain stem is the diencephalon, which is made up of the thalamus and hypothalamus. The thalamus is the gatekeeper for messages sent to and from the cerebrum and the spinal cord. The hypothalamus controls body temperature and vital urges such as thirst, hunger and fatigue.