What is the significance of Luke 22:44 where Christ's sweat was as great drops of blood in the garden of Gethsemane while he prayed?

Luke 22:44 talks about Jesus Christ's experience while he was in the Garden of Gethsemane. During a time when an angel visits him to strengthen him he begins to sweat blood. I would like to understand better the significance of this verse: 44 And being in an agony he prayed more earnestly: and his sweat was as it were great drops of blood falling down to the ground. * Did he literally bleed through his pores as could be interpreted from this verse? * What would cause him to sweat blood during a prayer to his Father? * What is the spiritual meaning behind this sweat of blood that came from his body in the Garden of Gethsemane? * Was he feeling pain that required an angel to strengthen him in order to bear what he was feeling?