To your heart, if the bubble is large enough it means cardiac arrest
If there is an air bubble in a liquid that is injected into your blood stream it is possible it will kill you. When this air bubble reaches your brain or heart problems can occur.
The blood-brain barrier, via the blood stream.
Your blood stream carries them.
The blood-brain barrier prevents various substances that could be poisonous to brain tissue (toxins), as well as many agents of infection, from crossing from the blood stream into the brain tissue.
cannabis flows through the blood stream in to your brain and makes your nervous sysytem faster
No it is not connected directly but you are getting oxigen that travels in blood stream from your lungs to brain.
Dye is put into the brain using an Intravenous method. They dye is injected into the blood stream where it travels to the brain.
The alcohol because it gets into your blood stream and can flow to the brain.
About 5 seconds
Breathed into your lungs from your mouth where it is absorbed into your blood stream, which is pumped up to your brain and around your body by the heart.
Heroin enters your blood stream to the brain instantly and slows down your memory when it kills your white blood cells (which help your body).
The caffeine enters the blood stream and travels all over the body.