Human brain


The human brain is the most complex organ in the human body. It controls the central nervous system (CNS), by way of the cranial nerves and spinal cord, the peripheral nervous system (PNS) and regulates virtually all human activity.[1] Involuntary, or "lower," actions, such as heart rate, respiration, and digestion, are unconsciously governed by the brain,[1][2] specifically through the autonomic nervous system. Complex, or "higher," mental activity, such as thought, reason, and abstraction,[2] is consciously controlled.