Your nervous system is the boss of all the other systems. It senses input from your environment and signals from inside your body that helps you react to keep you safe.

Major Organs

Brain -The brain sends and receives messages from every part of your body. The messages are sent through a network of nerves that extend to every part of your body.

Spinal Cord - The spinal cord is the main pathway for  information connecting the brain and nerves throughout your body

Nerves -Nerves are the highway of messages to and from your brain to each body part. 

Structurally, nervous system is divided into two types:

Central Nervous System (CNS) and Peripheral Nervous System (PNS).

The Central Nervous System is made of the brain and spinal cord. The spinal cord is the bridge that connects the brain to the peripheral nervous system. It starts from medulla oblongata and stretches to the lumbar region of the spine  or vertebral column. 

The Peripheral Nervous System is a network of nerves spread across our body. Think of Peripheral Nervous System

as a network of highways that connects the body with the Central Nervous System.  This highway has two way traffic.

Let's see how! When you hold a hot cup of coffee, sensory neurons in your hand transmit a signal to the brain through sensory neurons, also called afferent neurons, that the cup is hot. Your brain processes that information and send response through motor neurons, known as efferent neurons, that you must put that cup back. PNS consists of total 43 pairs of nerve, among which 12 originate in brain, named as cranial nerves and 31 originate from spinal cord, hence called as spinal nerves. 

Here you hear the word “neuron”. The neuron is the basic unit of the nervous system. It is the nerve cell which sends electrical signals to the brain.