Prana is the first energy: The word Prana comes from two roots. Pra means first, and na is the smallest unit of energy. Prana is therefore the first breath, the primal or atomic beginning of the flow of energy. Out of this first unit of energy manifests all aspects and levels of the human being. It is one and the same with kundalini shakti.
Prana flows in nadis: That kundalini, manifesting as Prana flows in certain patterns, or lines, or channels that are called nadis. There are said to be some 72,000 such nadis coursing through the subtle body that supports the physical body and its various systems. When the Prana flows across the latent impressions, they spring to life in the form of awareness in the conscious mind, in the physical body and brain.
Intersections of the nadis are chakras: When kundalini manifests outward, those thousands of nadis intersect here and there, forming the matrix of the subtle body. The major intersections are called chakras, and the five elements of earth, water, fire, air, and space manifest around these so as to form the gross body. Often, we speak of chakras as if they are in the body. Actually, this is somewhat backwards. It is more like the body has been suspended on the subtle chakras, with these chakras being formed or constructed by the major highway intersections of the nadis, which are none other than kundalini shakti.
Prana divides itself into five Vayus: When kundalini comes outward as Prana, the Prana operates in the body, it divides into five major flows called Vayus. These can be thought of as somewhat like major currents in one of the large oceans of the world, while there may be thousands of smaller currents. These five Vayus are the major currents that contain thousands of smaller currents.
• Prana Vayu operates from the heart area, and is an upward flowing energy, having to do with vitalizing life forces.
• Apana Vayu operates from the base of the torso, in the rectum area, is a downward flowing energy, and has to do with eliminating or throwing off what is no longer needed.
• Samana Vayu operates from the navel area, deals with digestion, and allows the mental discrimination between useful and not useful thoughts.
• Udana Vayu operates from the throat and drives exhalation, operating in conjunction with Prana Vayu, which deals with inhalation.
• Vyana Vayu operates throughout the whole body, having no particular center, and is a coordinating energy throughout the various systems.
Prana drives the ten indriyas: Prana is the source of energy that operates the ten indriyas. Five are the karmendriyas or instruments of actions, which are elimination, procreation, motion, grasping and speaking. Five are the jnanendriyas or cognitive senses, which are smelling, tasting, seeing, touching, and hearing. These ten operate through the chakras, and receive their power from the Prana.
Excerpt From swamij.com Article Kundalini Awakening