The Five Elements
Now let us discuss the constituents of us human beings. The first thing we must be familiar with when learning these constituents is the Five Elements.
The Five Elements are: Earth, Water, Fire, Wind and Space. There are two sets of five elements, the Five Gross Elements and the Five Subtle Elements.

* The Earth Element
First, we discuss the gross elements. Each or the Earth Element is the solid part of our body such as flesh and bones.

* The Water Element
The Water Element refers to the liquid in our body such as blood, semen, bile, lymph fluid, and so forth.

* The Fire Element
The Fire Element is the constituent of our body heat, in other words, the combustion of oxygen.

* The Wind Element
The Wind Element means respiration. We take in oxygen from the air and burn it inside our body. The oxygen which is high energy, combines with hemoglobin in the blood cells, is consumed and released as carbon dioxide. The Wind Element refers to the initial intake of the air in this process.

* The Space Element
The Space Element refers to the space or cavities in our body such as nasal cavities, oral cavities, and so forth.
Thus our body is constituted of these five elements.

* The Five Subtle Elements
What are the Five Subtle Elements? The Five Subtle Elements refer to the transformative process from the lower dimension to the higher dimension in terms of energy. Let me take an example. When a solid is heated, it changes into a liquid. When a liquid is heated, it changes into a gas and then to a plasma. If energy is applied further, nuclear fusion takes place; if more, it is sublimed to a pure light.
This is the process in which Earth is sublimed to Water; Water to Fire; Fire to Wind; and Wind to Space. In other words, the Five Subtle Elements are energies.

* The Five Vayus
Now let me explain the Five Vayus. Our body is controlled by the Five Vayus or winds, namely, Apana Vayu, Samana Vayu, Prana Vayu, Udana Vayu, and Vyana Vayu.

* Apana Vayu
Apana Vayu controls from the navel down to the soles of our feet. Its color is like that of smoke. It cleanses the body of deflilements, moves down the body wastes, removes agitation, brings mental stability and good sleep.

* Samana Vayu
Samana Vayu controls the part between the heart and the navel. Its color is red; it digests food and nourishes the body.

* Prana Vayu
Prana Vayu controls the part between the nose and the heart. Its color is gold; it takes in prana (cosmic energy) with respiration.

* Udana Vayu
Udana Vayu controls from the nose up to the top of head. It is bluish purple but the color occasionally changes. Udana Vayu makes our energy go up; by concentrating on this Vayu our spirit is raised when feeling low.

* Vyana Vayu
Vyana Vayu is the energy that envelops our body; it is often called an aura.

From Tathagata Abhidhamma Book 1