Medication

How do they know where to go, those little pills I take every day? How does Tylenol know to travel to the head when I have a headache, but to my back when it hurts? How do blood pressure medications know to go for the heart? How do blood thinners know to seek out the arteries? What about the way the appropriate medication ends up in my thyroid?

I imagine them all going down my gullet, turning on their tiny GPS systems, then sprouting little oars that let them paddle to their individual destinations. Bon voyage!