If you are interested in the specific material aspect and want the Western description in philosophical terms see "substance and accidents." The bread and wine retain their accidents, but are changed in substance. In the East, the Real Presence just is.
But how do you get spirituality transferred from your stomach to your heart/soul???
By the words of Christ and the invocation of the Holy Spirit.
It's a Sacrament, like Baptism. You might as well ask: When you get wet, how do you get spirituality transferred from your skin to your heart/soul?
In other words, you don't know...