This a concept idea based on one of the thumbnail ideas I drew up yesterday looking at the inner space as an alien world to fit the SCI FI theme and style. I envision the bloodstream as a cavern chamber with hardly any light and strange pillar like structures that make up some of the interesting forms inside the body.
These are the progression stages where I made certain decisions to change certain shapes, etc. The massive change I made in the final stages was to lose all the mysterious lighting because although this made the space feel alien it was too removed from an interior space.
As in the previous concept I experiemented with lighting trying some of the previous techniques and some new ones, the bottom image was interesting with the flood of red feels like it fits within this space but also has the impression of Mars and an unusual space.