Prana is a subtle form of energy that permeates the entire universe. Prana means life force or energy and is physical, mental, intellectual, sexual, spiritual, and cosmic energy. In yoga, the belief is, through practicing asana and pranayama, prana is brought into the body, increasing vitality. Prana flows through the body mainly in the nadis, or nerve/energy channels of the astral body.
Prana exists as both a negative energy and a positive energy:
Prana is an upward moving energy. Apana is a downward moving energy. When, after much practice, prana and apana come together at the muladhara chakra at the base of the spine, kundalini (dormant cosmic energy) is awakened. Nadis: Prana does not flow in a random fashion through the body. Prana flows through the Nadis. Nadis means nerve or energy channels. According to ancient yogic texts, the human body has approximately 72,000 nadis.
For the flow of prana, there are three major nadis:
Shushumna Nadi is the main channel that correlates to the spinal cord in the physical body. Ida Nadi is on the left of shushumna and is feminine or moon energy. Pingala Nadi is on the right of shushumna and is masculine or sun energy. Ida and pingala refer to sun and moon energy just as Hatha (Ha=sun, tha=moon) refers to the complementary energies in the body. In yoga, the goal is to cleanse, purify, and open the nadis to let energy flow freely throughout the body.
Chakras: Chakra is the Sanskrit for wheel or circle. Chakras are continually rotating energy or nerve centers within the body. Each chakra is connected to an emotional and psychological function within the body. They are the seven points along the shushumna where the pingali and ida nadis meet or cross each other. Chakras correspond roughly to the major plexuses or aggregation of nerves and ganglia of the central nervous system. As you awaken kundalini, it moves up the shushumna nadi, through the seven chakras toward higher states of consciousness.