So far in this page-turning Bubbles series we've covered bubbles in pots and in piping systems. Now let's talk about bubbles in you.
Your circulatory system is like a very flexible piping system. So a lot of the stuff in Bubbles 102 applies to your body too.
For one, your heart is a positive displacement pump. Get a big enough bubble in there (an air embolism) and all of a sudden it can't pump your blood. Consequences are left as an exercise.
But given its druthers, the bubble will rise to a high spot. Hopefully that's your head, and that's not a good place for bubbles either. Here a bubble could block blood flow to portions of your brain, giving you a stroke which could leave you more than half a bubble off at best.
Fortunately it's not hard to keep air out of your bloodstream. Health professionals have to make sure that hypodermic and IV needles are bubble-free before sticking you, and IVs are fed by the most reliable force we know of - gravity. And while you're at it, you don't want any bubbles in your douche bag either - believe it or not, this can cause an air embolism. (Given that colons are designed to handle gases, and can accomplish the remarkable feat of venting from the bottom, I don't think enema bags are a problem. But I understand that alcohol can be absorbed through the colon. Do with that information what you will).
That doesn't mean that there isn't gas in your bloodstream. There is, but it's in solution in your blood. Under normal circumstances it will stay there harmlessly.
But here in St. Louis over a century ago they found some abnormal circumstances. Workers there were deep beneath the Mississippi River in caissons and they were dying painfully. Unfortunately the chief engineer James Eads had discovered "the bends", a painful and often fatal condition caused by nitrogen bubbles in the blood.
Alright, I'm through. But I couldn't end a discussion of bubbles without linking to this.