 All right, here's another one. Living systems require energy. I find energy fascinating. It might be because I have some. So do you. You need energy. If you're going to try and maintain homeostasis, you better have some energy to help you pull it off. If you start getting cold, what's the first thing that you do when you start getting cold? You start shivering. And what is shivering? Dude, that's your skeletal muscles like contracting. And when they contract, they're not entirely efficient. And so there's heat. They're like little machines that when they do their work, they, there's a byproduct of heat released from the work that's being done. And that heat increases your body temperature, which is the whole point of why you started shivering in the first place. Awesome. It's a fantastic mechanism to maintain homeostasis, but holy energy. You need a lot of energy in order to make it so that that is possible. In this class, we're going to talk about energy. Energy is the ability to do work. We're going to spend, I think, three whole lectures talking about it. We spend one whole day just on the concept of energy. Because honestly, if you don't understand like what energy is, it's the, you're done. You do not function if you do not have energy. If your cells do not have energy to do the work that they have to do, game over, you are no longer a living thing. You are dead. That's a sad story. Don't let that happen. So let's just learn all about energy. The major processes that your body uses to get energy, your body gets energy from food that, and then releases the energy that's in the food from the process of cellular respiration. Makes me want to cry it so cool. And the food got its energy ultimately somewhere along the line, no matter what you're eating. It's somewhere along the line got energy from the process of photosynthesis, which is sunshine turned into sugar. No. How's that possible? How cool is that? Oh my gosh, this class is so cool. Okay, so we get to spend a long time talking about energy, which you need if you're alive. And you are, right? Okay, wake back up and let's talk about the next one, which is growth and reproduction.