Chakra is a concept referring to wheel-like vortices which, according to traditional Indian medicine, are believed to exist in the surface of the etheric double of man. The Chakras are said to be "force centers" or whirls of energy permeating, from a point on the physical body, the layers of the subtle bodies in an ever-increasing fan-shaped formation (the fans make the shape of a love heart). Rotating vortices of subtle matter, they are considered the focal points for the reception and transmission of energies. Seven major chakras or energy centers (also understood as wheels of light) are generally believed to exist, located within the subtle body. Practitioners of Hinduism and New Age Spirituality believe the chakras interact with the body's ductless endocrine glands and lymphatic system by feeding in good bio-energies and disposing of unwanted bio-energies.