The Nervous System is responsible for the every day and quick reactions made in your environment, such as reacting to pain, quickly moving out of the way in a life or death scenario, and maintaining your heart beat at a moderate pace after adrenaline has hit the body. All these factors allow your body to react quickly to avoid injury or death; the brain is responsible for sending the split second decisions that allow your body to react to danger.
The Nervous system is made up of the Central and Peripheral Nervous system. The Central Nervous system contains the brain and the spinal cord. The CNS is in charge of reading and deciphering messages sent by nerves and giving appropriate reactions when necessary. The Peripheral Nervous system is made up of all the nerves outside the brain and spinal cord; it is divided into the Somatic and autonomic nervous system. The Somatic nervous system contains the sensory and motor nerves. The Autonomic nervous system is divided into the sympathetic and parasympathetic nervous system. The sympathetic nervous system prepares for emergencies automatically. The parasympathetic nervous system is the automatic system that conserves body activity and keeps the body stable after an emergency.
The Nervous system contains many nerves in the most important parts of the body: radial, ulnar and median nerves connecting the arms to the spinal cord; Brachial plexi connecting the shoulders to the spinal cord; intercostal nerves following the chest; sympathetic trunk following the spinal cord to the legs; and many more cutaneous nerves that follow our hands and fingers. Tibial, common peronal, deep peronal , superficial peronal, and saphenous nerves follow the legs. Femeral, pudental, sciatic, genitofemoral, and obturator nerves follow the waist. All of these nerves connect back to the spinal cord where they are relayed back to the brain and processed. These major nerves are necessary to receive feedback from the body; without them we could not move our hands, feet, or any other major appendage in any kind of controlled manner.
Nerves are the main receptors of the body and they are the main component of the nervous system being able to send or receive messages from other parts of the body by an Electrical Impulse. An Electrical impulse is a charge of electricity that travels through nerves to the Central Nervous System in the brain to be processed. Nerves are made up of individual components called neurons, which sense touch, heat, or other environmental factors and send an appropriate message to the brain. The Neuron is made up of a few basic parts: The Cell Body, which is the command central of the neuron and reads and sends messages; the Dendrites, which carry electrical impulses towards the cell body to be read; the Axon, which carries electrical impulses away from the cell body for other cells to read; and the Axon Terminals, which is an extension of the Axon where the impulses sent by the Axon are delivered to another cell. Synapses are the gap between nerve cells that send chemical messages to each other to deliver the messages that the cells detect. Myelin is a substance found on the Axon that helps send the electrical impulses more efficiently. However, there are certain diseases that attack the Myelin and slow down or stop the electrical impulses. (See Pathology/Maladies; Multiple Sclerosis)