Vayu, the vital breath is regarded as the element of air at a material level. In Vedas it is mentioned that Vayu includes the concept of space or Akasha. Space in motion is air, while air at rest it is ether. These are the two sides of Vayu, which is the unity of air and ether. Ether is the field in which Vayu as a force operates. Vayu is the power through which everything comes into manifestation and into which everything eventually returns.
Vayu is not just the material element of air and space but the cosmic principle of energy and space that pervades body, mind, and consciousness. The entire manifest universe arises from space and energy which is Vayu at an outer level. At an inner level, Vayu stands for the formless principle of air and space, the invisible Brahman behind the visible world of the earth, water, and fire elements, the realm of name and form. Pranamaya Kosha consists of five types of Vayu namely Prana, Apana, Vyana, Udana and Samana. These are the vital principles of basic energy and subtle faculties of an individual that sustain physiological processes.
Prana vayu draws the universal life-force into the body for distribution, and finally, its expiration. The subtle or gross materials that enter the body are a result of Prana vayu. All sensory perceptions and respiration are due to Prana vayu. It operates the autonomic nervous system of the cervical region, governs the verbal mechanism of the vocal cords, the movements of the gullet and the respiratory tract.
Apana vayu is responsible for the elimination of waste products through the lungs and the excretory system. By controlling the lumbar portion of the autonomic nervous system of the body, it governs the excretory system and its related vital organs such as the kidneys, bladder, genitals, colon, and rectum.
Vyana vayu is present throughout the body and holds all of the parts together. Its work is extension, contraction, and flexion of the muscles, tendons, and ligaments; the stored-up energy of the muscles. This vayu maintains blood circulation in the physical body, and gives the body shape, flexibility, and sensitivity. Since it is all-pervasive it is usually referred to as “Trivikrama.”
Udana vayu is responsible for expression through speech. It is the upward moving energy. It is the natural intuitive force, which separates the astral body from the physical and help in maintaining erect position of the body.
Samana Vayu is located in the navel region it governs the internal balance of the prana and apana vayu. Samana vayu controls the process of digestion and assimilation by directing the secretions of the digestive system, and regulates the organs of digestion; the stomach, liver, pancreas and intestines. Just as oxygen is the supporter of combustion in the material world Samana vayu is to the Jataragni, the digestive fire. Samana vayu influences metabolism and metabolic disorders. Since it is concentrated in a small region and yet has its effect to all parts of our body this vayu is referred to as “Vamana.”
In addition to the five vital forces, the Natha tradition explains the beneficial function and importance of five sub-vital forces called upa-pranas.
The upa-pranas are Naga, Krikara, Kurma, Devadatta and Dhananjaya.
Naga vayu functions are belching and rising of Consciousness.
Sneezing, hunger and thirst are the Krikara vayu functions.
Kurma vayu works the automatic movement of the eyelids while winking, arms and legs while in movement, etc. just like how a pneumatic cylinder works in mechanical world.
Yawning is the result of the Devadatta vayu.
Dhananjaya vayu responsible for opening and closing of heart valves and is concerned with coma, swooning, trance and does not leave until after death. Once this vayu exits the body starts to decompose.