Nervous system, its divisions and Functions of nervous system

Nervous System
The nervous system and the endocrine system are responsi­ble for regulation and coordination of body parts. To­gether, they maintain homeostasis. The nervous system permits a quick response to external and internal stimuli, while the endocrine system is slower to act but provides longer-lasting effects.
Divisions of the Nervous System 
The nervous system has two major divisions: the central nervous system and the peripheral nervous system. As mentioned earlier, the central nervous sys­tem (eNS) includes the brain and spinal cord, which have a central location-they lie in the midline of the body. The peripheral nervous system (PNS), which is further divided into the somatic division and the autonomic division, includes all the cranial and spinal nerves.
Nerves have a peripheral location in the body-they project out from the central nervous system. The division between the central nervous system and the peripheral nervous sys­tem is arbitrary; the two systems work together and are connected to one another, as is illustrated in a reflex arc (discussed later in the chapter).
The nervous system is divided into the central nervous system and the peripheral nervous system. The CNS lies in the midline of the body, and the PNS is located peripherally to the CNS.
Functions of the Nervous System 
The nervous system has three specific functions:
Permits sensory input. Receptors present in skin and organs respond to external and internal stimuli by generating nerve impulses that travel to the central nervous system (CNS), consisting of the brain and spinal cord.
Performs integration. The CNS integrates (sums up) the input it receives from all over the body. Integration in the brain allows us to make decisions about the body in general. The CNS then sends out nerve impulses to effectors.
Stimulates motor output. Nerve impulses from the CNS go to the muscles and glands. Muscle contractions and gland secretions are responses to stimuli received by receptors.