As per Hindu mythology and as a matter of fact human body or every creature human beings, livestock, animals, birds, fishes, plants and trees are depends upon panch maha tatva or bhuthas.

Five basic elements of survival

1). Prathavi ( Earth ) - Gives shape of body through bones, tissues, muscles, skins & hairs.
2). Vayu (Air) - Helps respiration and stimulates the nervous system.
3). Agni ( Five) - Gives motion, vigous & vitality to body also helps in digestion, stimulation etc.
4). Jal ( Water ) - Represent blood, secretions of glands etc.
5). Akash ( Atmosphere ) - Builds the character and man's mental and spiritual faculties.

Sun indicates light ( illumination ) will power, generosity, solar system, luck or fate, mobility and in body. It rules over bone, eye, heart, spinalcord, blood circulation and soul etc. Hence east direction is auspicious, it belongs to lord Indra.

Earth has four cardinal directions but here in vastu, we consider Eight directions and lord for each directions are as under

East - Lord Indra.
North east - Jupiter.
North - Mercury & Lord Kuber.
West - Lord Varun & Lord Saturn.
North West - Lord Vayu Dev.
South - Mars, Pluto or Lord Yama.
South East - Venus and Lord Agni Dev.
South West - Pitra Naritrya Devils & Lord Rahu

All these are corresponds to the five senses of human body.

Sight ( Eye )
Sound ( Ears )
Smell ( Nose )
Taste (Tongue )
Touch ( Feeling )