"Nervous system is the chief controlling and coordinating system of the body. It controls and regulates all voluntary and involuntary activities of human body. There are three characteristic properties of nervous system of human body; Sensitivity, Conductivity and Responsiveness Neuron is the unit of nervous system: The structural and functional unit of nervous system is called neuron. It is a special type of cell with a cell body and cell processes. For more details about the structure of neuron, see the basic anatomy article””. Parts of nervous system: Nervous system of human body is divided broadly into two parts; Central Nervous System (CNS) and Peripheral Nervous System (PNS) CENTRAL NERVOUS SYSTEM (CNS) : Central nervous system includes brain and spinal cord. PERIPHERAL NERVOUS SYSTEM (PNS) : Peripheral nervous system includes all the parts of nervous system except brain and spinal cord. It is further divided into two components; Somatic nervous system and Autonomic nervous system. Nerves: Nerves are solid cords composed of bundles of nerve fibers (each nerve fiber is an axon with its coverings) bound together by connective tissue. Nerves are of two types; Spinal nerves and Cranial Nerves. Spinal Nerves: Spinal nerves arise from the spinal cord. There are 31 pairs of spinal nerves in human body. For more details on spinal nerves, see the basic anatomy article “”. Cranial NervesCranial nerves arise from the brain. There are 12 pairs of cranial nerves in human body. For more details on cranial nerves, see the basic anatomy article “”."