There is a shift at the level of the fourth chakra. While the first three chakras are associated with survival, regeneration and power in the world, the heart chakra or anahata chakra is the site of the beginnings of compassion for others. Anahata means the unstruck sound. Meditation on this chakra is said to reveal the underlying sound of the universe.It is the place where resides our Spirit, our true Self, which is eternally pure and unaffected by anything, like a shining diamond hidden within us which witnesses all our actions.It is a twelve-petaled lotus and its syllable is "yam". Balance in this chakra is expressed by empathy and caring for the suffering in the world. This is represented by the shape of two triangles in the chakra, one pointing up, the other down. This symbolizes being equally connected to the earth and heaven.
After Self Realization, our attention becomes for the first time connected to our Spirit and we gradually become aware of it. Our misidentifications with our ego or conditionings drop and we start becoming identified with our Spirit, which is our true nature.
It is from our heart that the compassion and love manifests, and also the heart chakra is the one that gives us the sense of responsibility and pure behaviour towards others. The heart chakra manifests in the center (at the level of the sternum bone) as complete security and confidence. All our worries, doubts and fears are destroyed when the heart chakra is fully enlightened by the Kundalini.
On the physical level, this chakra looks after our heart and lungs.