 Blood is, I mean, for the next chunk, there's going to be so many times where we're going to reference further learning about function in physiology. And it's almost disrespectful to talk about the functions of blood right now because we can't go into any of the details. We don't have time. We do want to know all the structure, but we definitely have to have like a general picture of bloody function before we move into a structure just so we can know, like, what are we learning about and why. But blood, holy important functions. Blood plays multiple, multiple roles in maintaining a relatively constant internal environment. You remember from the very beginning of the course that process is called homeostasis. One of the biggest bloody functions of blood is transport. This is the most intuitive transport because it's a fluid flowing from your heart to all over the place everywhere else and why is it doing it? It's doing it so it can take things places. What is it transporting? Dude, probably the biggest and most important thing that it's transporting. And, you know, statements like that are totally relative because the next one that I say it's transporting is like I'm going to say, oh, this is the biggest one. But gases for gas exchange, this is huge. This is why we have an entire circulatory system that goes to the lungs. So that we can have gas exchange take place. We need oxygen and we need to get rid of carbon dioxide and that is facilitated by blood. We also transport nutrients. And again, this is kind of a no-brainer but all the work that you did in your digestive system, breaking apart molecules, we've got a blood supply that's going right there and it's picking up all that digestive deliciousness and getting it into your blood. And then your blood, like who cares? You definitely don't want to leave it in your digestive tract. We want to share the wealth. So the blood stream will take the nutrients to other cells in your body that need it. Everybody needs nutrients and that's a really important job. Another thing that is transported in the blood are chemicals and these chemicals enable communication. And I'm just going to throw it out here that the primary communicating chemical that we throw into the blood is a hormone. Hormones are part of the endocrine system and in fact, that's the definition of a hormone. It's a chemical that's dumped into the blood from one location and it travels through the blood and affects a target somewhere far away. Hormones, holy importantness. Okay, transport, fantastic. Blood also plays a massive role in the immune system. And today we're going to talk about white blood cells because you are really the primary soldiers of the immune system. And so we're going to get the anatomy that will be necessary for the physio that we're going to do on how the immune system works. And then your blood plays a role in not only nutrients and gases but in maintaining the homeostasis of your body in several areas. Let's just put homeostasis and several what, like, factors need to be maintained in a homeostatic balance. And for example, your blood helps you maintain pH balance in your whole system. Your blood helps you maintain ion balance, like calcium ions and sodium ions and potassium ions. These things are really important for physiological function and so your blood helps you maintain those things in the proper levels. And then there was another one that I just thought of. Oh, body temperature. Your blood plays a role in keeping you warm by having your vessels like vasoconstrict in your extremities and keeping your blood in your core to keep you warm or you start getting hot and your blood vessels in your extremities and close to your skin actually vasodilate, which is why you get red when you go running because you're doing all this vasodilation to get rid of the heat that you're producing while your muscles are working. So they help the, if you see somebody with a little red face, it's because their blood is trying to cool them off, get the blood close to the surface so it can come in contact with the air and get rid of some of that heat. This, I mean, we will talk about all of it in physio. Let's look at what blood is made out of.