 Hey everybody, Dr. O here. I'm going to introduce our unit on biochemistry by talking about the elements that make up the human body. So first things first, you might be saying, wait a minute, I signed up for a biology class, not a chemistry class, but you have to understand that biochemistry is critically important. Right? All of the basic physiological properties that occur in a human body take place at the chemical level. So there's a lot of chemistry involved in biology, just so you understand that. All matter in the world, looking at these elements here that make up a human. All matter in the world come from, in the natural world come from 92 elements. We cannot produce these elements. We can take them and use them to build a lot of other things and the things that we can't build are called essential, meaning we have to eat them, we have to consume them because we can't produce them, but we cannot make these elements. This is where you get this idea, right, that you are what you eat, right? We have to, we eat most of these elements. We get oxygen from the air we breathe, but for most of the elements we actually get them by consuming them. So the elements come from the natural world. We take them up and make them a part of who we are. All right. So if you look here at the human body, just so you know, carbon, oxygen, hydrogen and nitrogen make up 96% of a human body. So there are lots of other elements inside of you, including things like vanadium and gold, all manner of things, but those are in trace amounts. 96% of you is carbon because you're a carbon based light form. Hydrogen and oxygen because you're probably about 60% water and nitrogen because we get that from the proteins that we consume. And then all of your macromolecules like your carbohydrates, lipids and proteins, all of them are going to have carbon, hydrogen and oxygen as well. So those are the four key ingredients in making human being and then you just sprinkle in all the rest of them. So my favorite question to pose though about this is how much are we worth? If you take the elements that make up the human body and you take their value, how much are we worth? Now personally, each and every one of you is priceless, right, we are priceless living things, but if you just look at the raw materials that were made up, we're made of the same materials as everything around us. If you put these raw materials together, what is their value? Now you're going to see different numbers, but I generally agree with this number here that for a 175 pound person, you're going to be worth about $160 worth of elements. It's an awfully low number if you think about it, but the most abundant elements in the body are actually very cheap. Think about hydrogen and oxygen, think about water. The more expensive elements in the body, there's only trace amounts, almost negligible amounts in the body. So if you take all the elements that make up the typical person, they'd be worth about $160. Now what makes us worth so much more than that is because we're living, right, we're worth more than a table or things like that. All right, so I think that's a nice introduction to biochemistry and a look at the elements that make up you and make up me. I hope this unit helps. Have a wonderful day. Be blessed.