system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What exactly happens if air trapped in a needle is administered into the bloodstream?
gpt
A few bubbles of air won't harm you, but a sufficiently large  amount can cause an embolism. An embolism is when the air blocks blood flow which can cause tissue death. If this happens in the heart, lungs, or brain, you die.