What is the nervous system?

The nervous system is responsible for relaying messages from the brain to the muscles to create movement. At the same time the endocrine glands release hormones that ensure the smooth orchestration of body systems. The nervous system stimulates skeletal muscles to contract in order to create movement at the joints.

The nervous system is one of the two organ systems in the human body that functions in communication and control throughout the body, integrating the functions of all other organ systems. It functions in rapid communication.

The structures of the nervous system include the brain, spinal cord, cranial nerves, peripheral nerves, and the special sense organs. The two major subdivisions of the nervous system are (1) the central nervous system (CNS) and (2) the peripheral nervous system (PNS). The CNS consists of the brain and the spinal cord. The PNS consists of the network of peripheral nerves, the autonomic nervous system, and the special sense organs such as eyes and ears. The autonomic nervous system consists of the sympathetic (flight or fight) and parasympathetic (rest and digest) nervous systems. The neuron is the basic unit of the nervous system. There are efferent (motor) and afferent (sensory) neurons. Motor nerves carry electrical messages to effectors such as muscles. Sensory nerves carry sensory information from the periphery to the CNS for processing. Most neurons consist of cell body, dendrite, and axon. The capacity of neurons to communicate rapidly is dependent upon the myelin sheath.

• The sympathetic nervous system ensures fast and efficient action by flooding the body with adrenaline. This increases the heart rate, blood flow and blood pressure, speeds up breathing and diverts blood from organs to muscles.
• The parasympathetic nervous system works as an antagonist to the sympathetic nervous system: the heart beat is slowed down, blood is returned to the skin and digestive system and normal body functions are restored.