 Okay, so our last theme that we're going to talk about is homeostasis, and for this one, this is actually a little bit more of a physiological theme, but hopefully as you know from theme number one, structure determines function. So the structures of our body systems enable the functions that maintain this homeostasis. So let's look at all the body systems, and first of all, probably define homeostasis. Homeostasis is a... well, I'll give you a definition. It's the maintenance of a relatively constant internal environment. So body systems work together to maintain a relatively constant internal environment. They do this because cells can't function if the pH goes off, if the salt concentration goes wonky, if glucose concentrations in your blood go out of control. There are many characteristics that have to be maintained in a certain range, or you can't live in... your cells can't live in that environment. And organ systems are working together to do this. So let's just take a quick minute to list out the organ systems and sort of identify their overall function but as it relates to the maintenance of homeostasis. First of all, one of the biggest tasks of your organ system is to acquire nutrients to make energy. So nutrients are necessary to make energy. And you already know that cells make energy. So energy is required for almost all functions in the body in order to maintain life. And the mitochondria, the organelles, the mitochondria are where that energy production takes place. Nutrients that are required for this energy production, obviously the digestive system, are necessary to get food substances. We're going to talk about the digestive system in the time before our first exam. The digestive system gives you the nutrients, or it helps you absorb the nutrients from the food in the environment. You can have all the food you want, need ice cream a plenty, and if you don't have the respiratory system providing oxygen, you're not going to get any energy out of that. Well, you get a little bit of energy, but not enough energy to fuel your needs. So the respiratory system provides the oxygen that's necessary. Gosh, dang it, I just am... Oh, what the heck? Come on, man. Come on, man. Whatever, we'll figure this out eventually. And then another system involved in acquiring nutrients is the musculoskeletal system. So think about that. The musculoskeletal, how is that involved in acquiring nutrients? Most of us can't just sit here and get nutrients delivered. Like most of us don't have an IV delivering all the nutrients that we need. We have to go out and get food and eat, and muscles and bones help us do that. Okay, these guys, digestive and respiratory, are our first two systems that we're going to talk about before our first exam. Musculoskeletal, dude, that is fun times for exam, too. In fact, muscles and bones are the entire topic of our second session in the class, and we'll talk about how all the important structures to get you the food that you need and do other cool stuff like jump around. Another big task of body systems is to coordinate. And guess who does that? We have major coordinating efforts by the nervous system, and the endocrine system. Nervous system is brain spinal cord neurons. Endocrine system is the production of hormones in places like the pituitary gland. The hypothalamus is involved in sort of regulating that. We have adrenal glands. We have the pancreas has endocrine function. This is actually exam three. I'm going to make a little note here. This is exam one. So you can see how we're structuring the class. We actually spend an entire session, an entire six lectures on the nervous system and the endocrine system, because they are these coordinating systems. We have a big role of transport in, like we have to transport nutrients and even hormones around the body. And who does that? The cardiovascular system. So blood, heart, vessels, that is the system that's transporting good stuff and waste. So a fourth task to help us maintain homeostasis is waste removal. And who's involved in that, my friends? You would think digestive system, digestive system, yeah, we definitely get some doodoo out of our systems. But I'm going to argue that the doodoo was never in your system in the first place. So the actual, like, we're just sending something through and not bringing it into the body. For the most part, there's a little bit of waste removal that happens from metabolic processes in the digestive system. So if you want to put it in there and make a case, I certainly wouldn't mark it wrong. But the big waste removers, the urinary system with the kidneys, that's where our urine is produced, and the kidneys literally filter your blood. And then you might not think of this one, but the respiratory system is a big waste removal person. And the waste product is being removed. Carbon dioxide, man, that's actually the biggest reason why you breathe to get rid of the carbon dioxide, because carbon dioxide is not messing around. Those are big, important functions. You know what? You got to protect the whole setup. And we'll look a little bit at the immune system, lymphatic system, like we'll spend a little bit of time with protection. We'll also look at integument. And we're going to do that in this first session. We're going to look at skin, because skin actually plays a big role in protection. And then the last one, you can definitely argue whether this body system is related to homeostasis or not. The reproductive system, we will talk about the reproductive system at the end of class. I never skip it because it's way too cool. And it's about passing, like it's about continuing our critterness, which is sort of homeostatic, because if we die and don't carry on our genes, then we're not in homeostasis anymore. Okay, but really reproduction is totally a bizarre thing that, dude, why would anybody do it? The only reason why we do it is to keep the species going. And good thing for the most part, what comes out of us is cute. And the process of making those cute things is fun. So that means that we will continue doing it. Okay, those are your themes. Keep them in your brain. Get comfortable with them. Now the last three sections of this video, we're going to talk about the content for lab and go through some terminology and words that you're going to need to know. Let's do it.