 So, organ systems work together to maintain homeostasis. Now, we're going to talk about the role each organ system plays in the maintenance of homeostasis. And I have some images, just general images of organ systems, and I just want to give a real quick woof woof to the OpenStacks team because they had, let's just talk about this for a second. OpenStacks has created all these incredibly high quality textbooks that are completely free. You can go online and you can get this anatomy and physiology textbook completely free. I use their images in as much as I can because everything is free and open. I can modify it, I can change it, whatever. So, you can go search for these things. If you're interested in access to these images, that's where I'm getting them. Okay. So, we're going to look at specific roles of organ systems related to homeostasis. And let me start out by saying not everything that an organ system does is homeostatic. So, there are things that organ systems do that don't have anything to do with homeostasis. There are things that organisms do that don't have anything to do with homeostasis. Homeostasis must be related to the extracellular fluid. In this class, you're going to have an integration project. One piece of the integration project is how the topic that you choose relates to homeostasis. So, somehow you have to choose a topic that relates to the extracellular fluid. If you can't do that, then you don't have a topic that's going to work for that project. So, you have to choose a circulatory system. I hope that even after just this conversation so far, I hope that you have a sense that, dude, the circulatory system or the cardiovascular system is all about circulating, that says circulating, extracellular fluid. The circulatory system is about exchanging extracellular fluid. Circulatory system brings in nutrients to cells, maintains ion concentrations, and takes waste far away. So, it is able to circulate and manage the state of the extracellular fluid. There are multiple body systems that are involved in nutrient acquisition and basically any raw materials required for metabolism. So, I have four body systems here that play a role in getting materials for metabolism. That's metabolism. Oh, geez. That says metabolism. What does that affect the extracellular fluid? Well, you need energy in order to do all the other functions. Circulatory system is not going to work unless you have a heart that is beating and you need metabolic reactions in order to make that happen. So, the materials that you need for those metabolic reactions come from the digestive system. That's where you get your glucose, your proteins, your nucleic acids, your raw materials come through the digestive system. The respiratory system. What are the raw materials related to metabolism that you get in the respiratory system? Oxygen. How about musculoskeletal system? Like, what is this? Why are they involved in getting materials? Dude, you got to go out and hunt for your food. You got to go get it. The doctor takes muscles and muscles work only because they are attached to bones. Okay, so we get some energy. My next set of little body systems, these guys are all involved in waste removal and they are involved in the removal of wastes that if they aren't removed, they contaminate the extracellular fluid. The digestive system is actually involved in the removal of some substances from the body, some ions and molecules from the body. Respiratory system, we get rid of carbon dioxide. That's really important to get rid of. And then urinary system. We're going to get rid of various metabolites. The urinary system is also involved in calcium homeostasis and other mineral homeostasis. And it's actually involved in blood pressure homeostasis as well. Okay, we have some body systems that are involved in coordinating the whole thing. So these guys are basically integrators. Coordination, oh, good Lord. Coordination and communication. So that is the nervous system and endocrine system. These are your integrators and they are instructing effectors to carry out homeostatic actions. And we'll talk about that in just a second. The last, oh no, not the very last, the almost second to last set of the lymphatic system. And this is actually skin. We'll throw immune in here. And these systems are about protection. And protection from invaders, which then can disrupt the nature of the extracellular fluid. You can imagine like if you get an infection of bacteria, they, for lack of a better way of explaining it, they're going to pee inside your extracellular fluid. And if they're peeing all over in there, like that's going to change the nature of your extracellular fluid. And usually that makes you feel like crap. And so then you get sick and your immune system will help you deal with that. The skin is protective because it prevents that stuff from coming in. And then of course, this is the one that I'm going to argue with in homeostatic about this at all. The reproductive system is about procreation, making more of ourselves. I guess you can argue that if you don't make more of yourselves, then it doesn't matter if you maintain homeostasis because when you die you're done. So as a species, we'd all be extinct if we didn't procreate. And so in a really big perspective, I guess that is homeostatic. But that's kind of an enormous reach. And when you look at reproductive function, it is highly on homeostatic. Like it's kind of crazy that we are able to reproduce it all because especially for the ladies when we hold those little baby parasites inside our uteruses, that's definitely like our whole system goes, okay, all right. So that's kind of an overview. You can imagine that, I mean if that's what we're going to discuss in this course, yeah, we're going to go a little deeper than that. All right. So the next thing I want to talk about is the things that are required. Like what makes up a, oh gosh, like a system, a pathway that is maintaining homeostasis. What are the parts that are going to, how are these body systems going to work together and send messages to maintain homeostasis? Something like that.