Seven major chakras or energy centers exist, located within the subtle body. Practitioners of Hinduism learn that 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.
Much of the original information on Chakras comes from the "Upanishads", which are difficult to date because they were passed down orally for approximately a thousand years before being written down for the first time between 1200–900 BCE.
The Seven Major Chakras
Muladhara: The Base Chakra or root chakra is related to instinct, security, survival and also to basic human potentiality. This centre is located in the region between the genitals and the anus. Although no endocrine organ is placed here, it relates to the gonads and the adrenal medulla, responsible for the fight and flight response when survival is under threat. In males, there is a muscle located in this region that controls ejaculation. A parallel is charted between the sperm cell and the ovum where the genetic code lies coiled and the kundalini. Muladhara is symbolised by a lotus with four petals and the colour red. Key issues involve sexuality, lust and obsession. Physically, Muladhara governs sexuality, mentally it governs stability, emotionally it governs sensuality, and spiritually it governs a sense of security.
Vishuddha: The Throat Chakra relates to communication and growth through expression. This chakra is paralleled to the thyroid, a gland that is also in the throat and which produces thyroid hormone, responsible for growth and maturation. Symbolised by a lotus with sixteen petals. Vishudda is characterized by the color light or pale blue, or turquoise. It governs such issues as self-expression and communication. Physically, Vishuddha governs independence, mentally it governs fluent thought, and spiritually, it governs a sense of security.
Sahasrara: The Crown Chakra is generally considered to be the chakra of pure consciousness. Its role is somewhat similar to that of the pituitary gland, which secretes hormones to communicate to the rest of the endocrine system and also connects to the central nervous system via the hypothalamus. The thalamus is thought to have a key role in the physical basis of consciousness. Symbolized by a lotus with one thousand petals, it is located at the crown of the head. Sahasrara is represented by the color violet and it involves such issues as inner wisdom and the death of the body. Sahasrara's inner aspect deals with the release of karma, physical action with meditation, mental action with universal consciousness and unity, and emotional action with "beingness"
The primary importance and level of existence of chakras is in the psyche. However, chakras have a physical manifestation as well. There is a relationship between the positions and functions of the chakras and of the various organs of the endocrine system. There is a marked similarity between the positions and roles of the chakras, and the positions and roles of the glands in the endocrine system, and also by the positions of the nerve ganglia (also known as "plexuses") along the spinal cord (branching to plexuses by endocrine glands or organs), interconnecting the two systems. Chakras have their physical manifestation in the body as these glands and their subjective manifestation as the associated emotional, mental, and spiritual experiences.