The body functions through various systems like the circulatory system, respiratory system, digestive system etc. Similarly there is a subtle spiritual energy system to provide energy to the physical as well as the subtle-body. The components of the subtle-body are denoted by the star against it in the diagram below.
The other systems can be seen by dissection of the physical body. But the subtle-energy systems are not visible to the gross eye. Only those people with an active sixth sense can perceive it. Some people equate this subtle-energy system with the nervous system but this is incorrect.
Just as the heart is the principle centre (organ) of the circulatory system and the brain of the nervous system, similarly the subtle-energy system has various subtle energy centres or chakras. They are known as ducts and centres (chakras). All the ducts and centres are situated in the Central Channel (Sushumnānāḍī). In the subsequent articles at the links below we discuss these subtle-energy systems in detail.