You enter a house through the front door and exit out the back, but what did you do inside? Most people just observe the valves opening and closing, but there are all these structures that make that happen, rotating all around, and never with the exact same motion. “Oh that’s too chaotic, too random,” some say. But if you walk down the street on a predetermined path, you’re in trouble. “It’s too chaotic the way you’re walking, man.” Sure it is, because I’m avoiding vehicles and people I may not want to run into! Your organs understand this variability and shift to, say, deliver more oxygen here or there. That’s feedback. The circulatory system is bouncing, man.