The meaning of prana is 'life force' or 'vital energy'. In the universal sense, prana is responsible for all creation. It is the prana within every created object, whether a planet, an asteroid, a blade of grass or a tree, that gives it existence, material form. If there were no prana within that object or manifestation there would be no form; it would gradually crumble and go out of existence. So, on the macrocosmic level, prana is like a vast, all encompassing sea of vital energy. Every object in creation is floating in that sea like a fish in water, and from that sea of energy we gain everything we need for life. That prana is known as cosmic prana or mahaprana.
From mahaprana each individual gains his personal existence. The quantum of prana which gives life to the individual is called individual prana. We separate it from mahaprana, but it is the same prana. If you fill a jar with water and place it in a lake or pond, the water inside the jar is the same as the water outside. We think of ourselves as separate entities or beings moving around in this world, but we are all part and parcel of the universal or cosmic prana. This cosmic prana or energy has been eulogized in all the ancient cultures and religions, and known as mahashakti, mahakundalini, mahamaya, the great mother. Through that mother we can connect ourselves to the highest reality or pure consciousness.
It is said that in the beginning there was just pure consciousness from which emanated pure energy or mahaprana. Pure consciousness and pure energy exist in the unmanifest dimension. However, when pure consciousness decided to become manifest, then it manifested through pure energy. So from pure prana emanated the first manifestation in creation which was sound. Sound is the most subtle aspect of manifest prana. Form gradually emanated from sound and from the subtlest form came all the objects of creation, including our own individual being. So all of us have our life within this concept of cosmic prana. Our real mother, our true mother, is mahaprana or mahashakti.
The prana within our individual being has been categorized into five groups, but we need to understand that the individual prana is one prana. We do not call it mahaprana, but will refer to this overall prana which gives us life as Prana with a capital 'p'. When Prana leaves our body then we will be clinically dead and gradually our form will disintegrate.
To understand the functions of individual prana we divide it into five main categories: prana, with a small 'p', samana, apana, udana and vyana. These are the five pranas which together maintain the entire function of our physical form.
Prana: Prana with a small 'p' is located between the diaphragm and the throat. This prana is an upward flowing force. It maintains the function of the lungs and heart, and is responsible for inhalation and exhalation, and for the swallowing and regurgitation of food. Although it is an upward moving force in general, it also has the ability to move downward in that region.
Samana: The next prana is known as samana. The word sam means 'equal' or 'same'. Samana is located between the diaphragm and the navel. Although it is a small area physically, it is very important. Samana is responsible for the digestive energy and coordinates and motivates the digestive organs such as the stomach, liver, pancreas and large intestine. If anything goes wrong with your samana energy then you will become weak and thin because you will not be able to absorb the nutrients in the food properly. It takes a tremendous amount of energy to digest, burn and separate the nutrients which we take in daily. That is one of the greatest pranic expenditures within our body.
Apana: The third prana is apana. Apana is located between the navel and the perineum in the pelvic region. It is a very important energy field which is responsible for sexual activity, procreation, production of semen and ovum, elimination of urine, faeces, gas, wind and expulsion of the foetus. This energy is mainly downward flowing, but we can also redirect it upward to the brain.
Udana: The fourth prana is udana. Udana is located in the head region as well as the limbs, between the shoulders and the fingertips, and from the hips down to the toes. It is associated with the motor and sensory nervous system. Udana controls an immense amount of energy. It coordinates and activates the nervous system, moves the limbs of the body and receives and categorizes the different sensory inputs from the external world. Udana is connected intimately with the functions of the five senses, eyes, nose, mouth, ears and touch. If this prana becomes weak or disturbed, we find it difficult to coordinate, balance and integrate our sensory and motor nerves.
Vyana: The fifth prana is vyana. Vyana is an integral prana. It exists throughout the body as an underlying reserve force, so if anything goes wrong in another area of prana, vyana can step in and support that weak or imbalanced area. Thereby vyana prevents diseases and imbalances from occurring in the different systems and parts of the body. Should vyana become weak or deficient then diseases will arise because there will be no back up system.
So here we have a blueprint of the pranic system within our physical body. Each one of these pranas is also related with a particular psychic centre, which is like the power station which generates the energy for that area. The psychic centre is much more subtle than the pranic area or the physical region. It is a vortex which is spinning around and around like a disc from outer space. It receives the very refined cosmic prana from the universe, absorbs it inside and transforms it, so that it can be utilized by our body for particular physical functions. The psychic centres are also responsible for igniting and illumining different regions in the brain so that we can access the higher faculties.
The psychic centres transmit energy to the physical and mental levels. For example, the centres related with apana, the downward flowing force between the navel and the perineum, are mooladhara and swadhisthana chakras. They are responsible for the evolution of our sexual energy, and the functions of urination and defecation.
The energy of samana, in the middle region, is related with manipura chakra, represented by the sun or a blazing fire. Manipura is the centre of prana, the storehouse of prana. Prana with a small 'p' is located in the region between the diaphragm and the throat, and is connected with anahata chakra, the heart centre, the centre of feeling and emotion. Udana, the energy from the neck to the top of the head, and arms and legs is related with vishuddhi and ajna chakras. Vyana is related with all the chakras together. This is a general concept of the pranic body which in yogic terms is called pranamaya kosha.
The five koshas are: annamaya, pranamaya, manomaya, vijnanamaya and anandamaya. Annamaya is the prana which gives form to our material existence. Within annamaya kosha, like a network or infrastructure, we have pranamaya kosha. Pranamaya gives life to annamaya. It is subtle, it gives movement to the physical form. More subtle still is manomaya kosha. Manomaya kosha is the energy of the mind. Without it the mind would not function; we could not think, remember, rationalize or even dream. We would be like total vegetables, in a coma.
When the energy of the mind becomes even more subtle, then we enter into the dimension of vijnanamaya kosha, the dimension of psychic prana. It is a very refined form of prana between the subconscious and the unconscious. This is the prana which comes to us in the form of visions, when we experience or hear something internally, intuition, prophecy, vision, darshan. Finally we come to the dimension of anandamaya kosha which is the transcendental realm. Here we transcend the normal dimension of prana and enter into the cosmic dimension. Then we experience the transcendental or cosmic prana, the mahaprana which exists in the unmanifest dimension at the level of Shiva and Shakti.