We have many different aspects and dimensions to our existence. We are far more than just the body and our thoughts. This was elaborated on by the Great Sages who described the five sheaths of our existence. Having a basic understanding of this will help to understand the five main types of Prana.
In order from the most subtle to the gross the sheaths go:
1. Anandamaya kosha, our spiritual body.
2. Vijnanamaya kosha, the psychic body/highest wisdom body
3. Pranamaya kosha, the energy body
4. Manomaya kosha, the mental body
5. Annamaya kosha, the physical body, or the body sustained by food.
These koshas all work together to form the whole of our existence and experience. In Hatha Yoga class, when we do Pranayamas, we are trying to work with the Pranamaya Kosha. The five main energies of this kosha are known as Pancha Vayu, or the Five Pranas. They are prana, apana, samana, udana, and vyana.
1.Prana- in refrence to Panch Vayu, refers to an energy that governs speech and respiration. It's primary home is between the throat and the diaphragm. This energy moves down and inward, the same as the breath we breathe.
2. Apana is the energy that deals with expulsion of wastes from the body and any downward moving processes. It's primary home is in the large intestine, and the lower pelvic area in general. Often in Hatha Yoga we alter the flow of this energy by forcing it to flow in the opposite way.
3. Samana is the energy that governs digestion. Think of it as the wind that stokes the fires of digestion and you will have the right idea. It help with assimilation of all things from food to memories and emotions. It's main home is around the navel center.
4. Udana is the energy of self expression and movement. It is also active with the upward and outward flow of breath during an exhale. Udana allows us to move gracefully, hold ourself erect, and express how we feel. It's main home is the region of the throat.
5. Vyana is throughout the whole body. It helps to control all the activities and bring together the other pranas to function properly.
Any more info than this on the pranas should be obtained directly from your friendly Yogacharya! I am always leery when I see "vayu flows" in magazines, I have watched people get sick numerous times from doing practices in an improper or excessive way. Instead of trying to beat a prana in submissions or do poses directed at them, try feeling them as you do each pose. What happens to Apana in an inversion? What happens with Samana when you do a long seated forward bend? What happens with Udana in ekapadasana?
The are other minor Vayus, and the number depends on what school of Hatha Yoga or Ayurveda you talk to. They control very specific things like belching, sneezing, yawns, and others.