 Hey everybody, Dr. O, and this is where we're going to talk about metabolism again as you can see here. We're going to talk about anabolic and catabolic reactions, but we're primarily going to do so by looking at the laws of thermodynamics, which actually tell us number one, why we have to eat and number two, why we have to eat so much. So let's kind of go ahead and jump right in. So the last number I saw that the average American eats 1,996 pounds a year. So this first law of thermodynamics that says that energy cannot be created or destroyed. It's a change form. It is the reason we have to eat. So you can see here at the top, we eat food and in the end, food becomes what? Food becomes ATP. So we're able to take the chemical energy that's built into our food and as we digest it and break it down catabolically, we can transfer that energy or we can change its form into ATP, adenosine triphosphate, the primary cellular energy currency that we use. So that's actually really cool. So you can see here catabolically, so you eat protein, you break it down to amino acids, which can then be used to produce energy. You consume carbohydrates, they can be broken down to glucose, which can be consumed for energy. You eat fat, same thing, can be broken down for fuel that can be used to produce energy. So those are going to be all these key catabolic reactions that lead to the transfer, the change of form from the energy, from the food we eat into the energy currency ourselves can use. Now you can also see a couple more catabolic reactions here too and that's because we store these things too. We can store, we have a pool of amino acids, obviously we can store amino acids in muscle and if we have to go and break down that muscle for energy, we can. We can store glucose in our liver and our muscles as glycogen and we can store fat. So we can actually, so every second of every day, your cells need to eat. If you just ate, they can use the food that's being absorbed into your bloodstream. If not, they will have to eat the doughnut you ate 10 years ago, right? Or the muscle that's in your thigh. So this supply of energy leading to a supply of ATP has to be constant. You can only store two to three seconds worth of ATP at any given moment. So what your body is eating, whether you have an eight in three days or it's been three minutes, your body is eating every second of every day. So that's going to be this first law of thermodynamics. We have to constantly be changing energy into the form we can use, which is ATP. The second law of thermodynamics basically says that our universe is falling apart, right? Order is not the law. The law is chaos and things are becoming more chaotic. The term you would see is entropy. But what that basically means is to be alive requires lots of energy because we're trying to have a very ordered complex living system in a world that naturally leads to decay, naturally leads to this entropy. So which is of course what happens when we no longer have a metabolism. But the reason this is important here, it goes back to that number. Why do I have to eat 2,000 pounds a year, right? That means that you're eating your body weight every month. Well that's because since the universe, overall the entropy or if you want to call it chaos in the universe is increasing, no metabolism can be more than 50% efficient. We basically, we have to waste more energy than we get. So our metabolism, if you take the sum of all the catabolic reactions occurring in your body, about 40% is going to be turned into ATP. The rest is lost as heat, so you can't see it on here, but heat. So the second law of thermodynamics says that our metabolisms have to waste a lot of energy. So 60% of the energy produced by your food intake this year is going to be heat, which is why it takes so much food, your own body weight almost once a month, just to get the energy you need to survive and store some for a later day. So that's going to be, and then so we didn't talk about the anabolic reactions here, but so that's the catabolic reactions, you see those green arrows. You can, we actually do, we add energy to build things and you see energy, ATP actually needs energy added to it. That's what your cellular respiration pathways do. But then as I've already mentioned, we store glucose as glycogen, we can store fat all throughout our body and we can store protein as muscle. Okay, so that's the relationship between your metabolism and the laws of thermodynamics, kind of interesting. All right, have a wonderful day, be blessed.