Fantastic Voyage - Environment Concept Notes

Thought of these quick concept ideas while walking home, quickly jetted them down into my phones notes, putting them here for a more accessible reference, and to show my logic behind my environment concept thumbs I'll be working on tonight.

1st stage - Throat
Like a cave, but dark, dank, ant colony reference, mushrooms? You can get stuck in phlegm patches which slow you down, also allowing bacteria to do damage to you while stuck, and to cause further infection - if allowed to reach/infect certain points, causes cough and swallow, meaning move on to next area. (have infection % bar?) 

Lungs
Slightly longer level, 3 stages. Like a forest/swamp upper is nice, light, airy, 'dandelions' particles, and villi, reeds then further down becomes more close knit with brambles and denser 'greenery' then bottom is swampy and wet and muddy and claustrophobic. Again phlegm issues here, and infection % bar.  

Heart
Harder again as blood is pumping, rivers, dam, estuary. You have to keep bacteria away from jumping into bloodstream to stop them travelling further around the body, while also avoiding being washed away yourself.

Brain 
Has symbols hidden in the folds? Lightbulb, mathematical signs, cogs, machinery, question marks etc? To show cognitive process, "computer" of the body. Level is harder to navigate - not just a straightforward path as have to travel across the webbing of the brain. Maze-like. Also have to be more destructive to be able to get through to certain areas eg destroy brain tissue strands to be able to get to all bacteria in different sectors/pockets. Certain "core" strands you cannot destroy - causes too much damage. This also reflects the possible damaging side effects of very strong antibiotics effecting the patient negatively. If not all bacteria reached in time and bacteria % bar filled, game over.