Prana is a subtle form of energy. Prana literally means "breathing forth" the universal life force. Through practicing asana and pranayama, prana is brought into and stored in the body, increasing vitality. Prana mainly flows through the body in the nadis, or nerve channels of the astral body.
Prana exists as a negative energy as well as a positive energy. Prana moves upward and apana moves downward. When the two unite at the muladara chakra (base of spine) kundalini (dormant cosmic energy) is awakened.
The most important nadi, or energy channel, (there are 72,000!) is the shushumna nadi which correlates to the spinal cord in the physical body. When kundalini is awakened it starts to move up the shushumna nadi, through the seven chakras toward higher states of consciousness.
In ashtanga yoga there are three locks (bandhas) that are engaged throughout the practice to prevent the dissipation of, and direct the flow of prana in the body, and convert it into spiritual energy. ?Jalandhara bandha prevents prana from escaping the upper body. ?Uddiyana bandha forces prana up the shushumna nadi. ?Mula bandha, when engaged, prevents apana escaping from the lower body and draws it up to unite with prana.
The chakras
From bottom to top the 7 chakras: 1. Muladhara chakra - at the anus 2. Svadhishthana chakra - at the genitals 3. Manipura chakra - at the navel 4. Anahata chakra - at the heart 5. Vishuddha chakra - at the throat 6. Ajna chakra- between and behind the eyebrows 7. Sahasrara chakra - at the crown of the head
