Welcome to introduction to human anatomy and physiology the human organism. This is the chapter 1 um lecture and I'm professor Mauy. So this is the first chapter. So I just wanted to kind of take you through what the expectation is. Watching a lecture video serves two purposes. one, it serves the online students as their lecture portion of the course and students are expected to watch the lecture videos and take notes. You may also find uh questions that are embedded in the lecture may show up elsewhere as discussion questions or homework questions in your course. So, uh it is important that you watch these lecture videos and take notes. You're taking notes because I write my own exams and your exams are based on the content of our lectures. Our lectures loosely uh follow the content of the textbook. And I say loosely meaning that it may not be in the exact same order as the textbook and I may put additional information in our lectures. Okay? So, uh again, that's why it's important. Your textbook is a resource for you to read from uh look things up, have additional uh visual aids, pictures, figures, tables that you should use. I try to provide different ones often in the lecture so that you have more than one visual aid for that topic content. So, you do want to be taking notes. Um this could be into your student lecture guides if you choose to do so. the student lecture guides are provided to help you pull information from the textbook. So you kind of have an outline of where we're headed in the lectures. Um and so again that's both for online and face toface. Then if you're in a face toface course this um recorded lecture serves as a review for you. Online students can start and stop the lecture any time. They can go back and review information. Whereas in in a face toface class um you don't have the luxury. you can interrupt me in class and ask a question, of course, but um in class, you're not starting and stopping lecture. So, it's nice to have this as a resource for face-to-face students to review some information as they're preparing for exams or maybe they miss something in their notes uh that day in class because maybe they write really slowly. Then you have this uh as an option. All right. So face tof face students of course you can ask I'll be presenting questions to you in class and you'll have the opportunity to participate that way. Online students will have those you know embedded into their canvas course. All right let's get started. And often uh just so you know what's written on the slide I give additional information. So um you are writing down potentially what's on the slide but you want to add anything that I've said verbally in class. uh and in this virtual class as well. Now the other thing about chapter 1 we what we cover in the lecture slides today or in this lecture that's what's covered on your lecture exams. Okay, that's all the content from chapter 1 for the lecture exams. Then you're going to find that what's covered in lab, some of that will be in chapter 1 as well, planes of the body, um directional terminology, etc. But if it's covered in lab, that's going to be on lab exams. So, we organize this class into lecture material will be on the lecture exams. Lab material will be on the lab exams. And that'll be a reminder that I give to students in person in the face tof face class as well as during those what to expect videos for the online classes. All right, let's get started. There we go. So, a little bit about the history. Your textbook doesn't cover any of this, but just to give you an idea how long um you know, the study of anatomy and physiology has been taking place. Uh it was 1543 that Andreas Viselius um wrote the first book on human anatomy. It was called dehumani corporus fabrica libra septum and that's Latin of course for on the fabric of the human body in seven books. So seven books on human anatomy. So when you look at our book you understand that we are studying a lower level than what you would expect in med school or even the sophomore level AMP one and two classes. Having said that, that doesn't mean that there's not a lot of information that we cover. we do. The human body is very complex. We don't know everything about it yet and we're still studying it today. So, we're not done. We're not finished and uh I don't know that we ever will be. There's always new things to learn. So the study of so again 1500s and that first book on anatomy a lot of what we know today in anatomy physiology um historically came from you know um well unfortunately illegal activities such as digging up graves bodies from graves um and those are the resurrectionists and so they were digging up bodies and they were you know getting paid to do that by doctors uh to do dissections. So that wasn't really allowed. It was illegal and um but anatomists and doctors scientists knew that was the only way to learn more about the human body. So some of the things that were done were not always legal but they did provide uh that information that we need today. So there's the history of anatomy and physiology and even you know procedures um development of anesthetics and um the development of sterilization techniques the things we learned um it took several years of course but valuable information. the the way it was uh learned, however, can be a little bit um you know, maybe distasteful to us today, but a little bizarre, maybe a little bit um dist well, distasteful is one way to put it, but uh morbid, a little bit morbid sometimes, right? But it provided a lot of information for us today. We wouldn't be where we are today without some of those things happening uh in the past. So, the study of medicine began with the standardized terms in Greek and Latin. And so why why Greek and Latin and then why do we need standardized terms? So the reason and a lot of students will say this class is like a whole new language. It is a little bit but it's not just unique to science. You see this in literature and other um other um classes as well that it's because historically um the languages the Greek language and Latin language those are considered the classic languages and those were the languages of the scholars that's the language that they used as they discussed and pondered scientific things as well as uh the you know literature and poetry and music but the languages of the scholars the early scholars And of course, um, the old world, we're in the new world, right? United States, uh, North America. The old world is where you have, uh, Greece and Rome and Italy and Austria. And as we look at, for example, anatomy physiology study, you know, this is coming from. It began in um, Italy, you know, Greece, Rome. So, uh, Rome specifically, but, you know, smaller areas as well. So not just Rome and Italy but the outlying areas and that's where a lot of the um if you know anything about the history of uh surgery um the autopsies that are done today it was very different. Surgeries were um actually open not necessarily to the public but to other doctors and important people in the um in the city and they were in these big galleries. Uh unfortunately the viewing was often difficult. So the surgery might be happening on the center floor and then the gallery had it was like a theater but with really steep uh seats going up. And a lot of the study of the first um dissections from in med schools then when they first developed the med schools they would go to these uh autopsies or surgeries or dissections. They weren't doing the dissections themselves um but they were observing it. So a lot different today. You guys in these classes will do some dissecting and um actually get a feel for where the organ uh organism has the organs and the vessels etc. And that wasn't the case in the early med schools. They didn't necessarily get to do the dissections. So but anyway, all right. So that's why we have Greek and Latin. We need standardized terms so that no matter uh the language you speak um there's an understanding of uh what you're discussing when it comes to whether it's directional terminology where something is found on the body. You know if you're going in for surgery and it's the right kidney that needs to be removed, you want to make sure that that's happening for the right kidney, not the left kidney. Um, and you also probably know in these days, um, doctors will also use a Sharpie or something to mark on the body because we cover up the majority of the body, right, when you're getting surgery. And so, just to make sure, but again, standardized terms, we got to have that language of communication so we know what each other is referring to and talking about. And that's not unique to anatomy, physiology. It's same for science. So if you're using scientific names for organisms, doesn't matter if you're in Australia or United States or Canada, wherever you might be, if you're using the scientific name, you're talking about the same organism as opposed to the common name. So you know that a lot of organisms have, you know, snakes, for example, have lots of different common names. Uh here in the United States and Missouri, a copperhead is very different from a what they call a copperhead in Australia. um excuse me, Australia for example. All right. Um so we do need that common language so we can uh communicate clearly with each other and understand what we're talking about. All right. So enough about the little bit of history. If you want to know more about history of of medicine, you know, I'm happy to talk about it. But moving on. So anatomy and physiology. Anatomy is the terminology that deals with the naming of things. It's called the morphology. So what do we call that structure? And so for this course we cover anatomy in the lab for the most part. U we'll use terminology uh referring to the names of cells and things when we're talking about the mechanisms um in lecture but anatomy is a lot of the lab is absolutely naming of the structures naming the bones and their features naming the muscles etc. So that's the morphology and will be covered in lab for the most part. We do a little physiology in lab but mostly we do anatomy. And then when it comes to how things function, the mechanisms by which these things occur, that's your physiology. How do these um structures, the morphology, how how do those structures work together? So studies the functions of those parts. So physiology is the functionality or the mechanisms. And so that might be the steps to endocchondrial ocification. So how does a bone form? What happens? What's the process? That's the physiology. And again, we cover most of that in lecture. So of course um we study these together. Now you can uh study these separately absolutely u we study them separately to a certain extent and then we're putting the pieces together. So we're learning the terminology and a lot of the naming of things in a in the lab for the anatomy and then how they work. That's our discussions that we have in lecture. And of course they're closely interrelated because form and function go together. What do you think happens to the function if the form is changed? So, this isn't just uh when we're talking about the human body. This could be any kind of mechanics um you know structures in your house. Uh absolutely what happens to the function if the form is changed. So, you might think that if you change the form, the function either changes or doesn't happen at all. So, depends on what we mean by changing the form. So uh in the human body if something doesn't develop quite properly maybe it's a bone doesn't mean that you can't use it at all but maybe to not not to the same degree as a fully formed or properly formed bone would work. The other thing is uh we see so we think of this when we talk about development but also as you age and the form changes. So you can use that same example of a bone. People that are getting knee surgeries and shoulder surgeries as they age that's often because of wear and tear and overuse and the you know the shape of the let's say it's the head of the humorris has deteriorated or changed in some way and now we have pain associated with movement there. So when the form changed the function changed it hurts and you can't use it properly anymore. So that's just a common example, but this really can be applied lots of places in the human body as well as um in your own home. If, for example, the screws come out of the hinge on on the door to your house, then your door is probably not going to open and close properly. So the form changed because it pulled away from the door frame and now the function has changed as well. So again, it's not always that it doesn't work properly, but it doesn't work as well or, you know, perhaps it it it stops working altogether. So it just depends. And then we can also apply this to cell function. So cells when they're first developed, they're considered immature. They're not ready to function yet. We change their form. We call that differentiation. We'll see that again later in the lecture. But that differentiation then means specialization. So basically, it becomes a mature cell ready to carry out its function. So that's a change of potentially the form of the cell adding some maybe uh organels that it needs to function properly and then that allows it to function altogether. So again lots of ways that we're going to be looking at form and function uh in this course. So anatomists um again they make observations and u perform dissection. That's what you're going to be doing in lab. If you're in an online class, your virtual labs in McGraill connect that is simulating what students who come into lab are going to do. So, you should be making observations and then we will dissect in this class um both in the face toface as well as the online classes. And the online classes you guys are getting that lab kit sent to your house that has the organs and the fetal pig that we dissect. So, we'll be doing hands-on dissection and of course making those observations. Observations means you're utilizing the information in the prelab list. What structures do I need to know? And then can you point them out and name them on actual bodies or models? And physiologists of course they're uh tasked with doing more of the experimentation stuff. So we will do in some experimentation both virtually for online students as well as in class um for the face-to-face students. So things like your analysis, pulmonary function, it is more common. So once uh several years ago, a student made the comment to me that there's nothing new in anatomy. Why you know don't we know it all already? uh while it is more common to discover new information about physiology because we don't understand everything every single mechanism that's occurring you know subcellular level as well as the cellular level and above. Uh anatomical discoveries are still being made as well. So um I've updated this I had a different uh example. So in 2013 there was a an additional uh ligament. The ligament is not new to the body. It had just never been named before. So in 2013, Belgian researchers named a ligament in the uh knee, but this is more current. So I've added this one just recently. So just a couple of years ago, um a membrane within the subacoid space. We will be learning about that in the brain. Um called the subacoid lymphatic like membrane or slim for short, S lm. It's in that subacoid space. They think it seems to function in separating the clean and not so clean or dirty cerebral spinal fluid uh during the flow but also it seems to have some immune fun functions. It has some immune cells associated with it. So protective so we can you know that's the basis we can take away from this is that it does seem to have a protective function in the brain. So they're still you know um looking at it. We don't know for sure, you know, exactly the functions, but this is a new anatomical feature. It's a very thin membrane. It's um similar to membranes found throughout the body. Um but absolutely not named before. Um we talk about the subacoid space. We talk about the fact that it has cerebral spinal fluid in it, but this hasn't made it into the textbooks yet. It's new. So until it's um a little more is discovered about it and of course upper level textbooks would have it maybe before we do but uh intro again we're doing a survey so we don't look at every single structure in the body. Um absolutely that's a that would be a very long semester for us but even my sophomore level classes we don't look at everything. So we look at plenty though, trust me. But anyway, so new discovery uh in January 2023. Um and again, so it is possible. Lots of things about the human body we don't know yet. So have um I don't like that this bar is maybe you don't see this bar. Well, I'm hoping that this bar isn't showing up for you in my Zoom screen, but I got a sneaking suspicion that it is. So, I'm going to read this sentence slowly so that if you can't see that, um, at least get that sent. So it says the human body is the sum of its parts and these parts. So that's that first sentence that you're not seeing potentially. So if you can see it, that's great. I won't know until I um stop this recording and look look at it later. But the human body is the sum of its parts and these parts can be studied at a variety of levels of organization. So the takeaway from this slide is the levels of organization anyway. But levels of organization and where we're going to look at these. So um we start at the uh smallest structure of course atoms. We talk about atoms and molecules and macroolelecules. So these first three listed here. We will talk about these in chapter 2 when we cover chemistry in lecture. And we do cover chemistry just in lecture. We don't cover it in lab. So that's why when you look at your lab schedule, you don't see anything for that. But we'll talk about um you know the protons, neutrons, and electrons that make up our atoms. We'll talk about that briefly. And again, it's one chapter of chemistry. It's not meant to be a full semester of chemistry by any means. So we're just, you know, kind of skimming the surface of chemistry. But you can't talk about a human body without having a little bit of understanding of chemistry. and the fact that atoms then work together. So atoms of elements like hydrogen and oxygen um react together to form things like water. Atoms form larger structures. So and this happens to be a water molecule. They show you here in this picture, but these are the hydrogens. That's the oxygen. So um H2O, there's the two hydrogens's and the one oxygen. But they uh react together to form larger molecules. Then molecules react together. So lots of molecules react together to make larger structures called macroolecules. So we'll be looking at those. So these are your things like proteins, your carbohydrates, your lipids, your nucleic acids. They're macroolecules. And it's those macroolelecules then that form together to make larger structures in our cells called organels. This happens to be um the mitochondria. mitochondrian is singular sorry and then mitochondria um plural. So this is a structure in our cells that undergo something called cellular respiration. So it utilizes nutrients we take in from our diet as well as the oxygen we breathe in to make a usable form of energy that we need ATP. So again ATP made by mitochondria in our cells. That's why we breathe in oxygen. We need that oxygen for cellular respiration that's occurring in our cells and most of those phases of that process are occurring in the mitochondria of our cells. You have lots of these little structures and so they're making that usable form of ATP that we need. Usable form of energy, excuse me, that's called ATP. Adenazine triphosphate is what that stands for. So we'll be hearing about ATP throughout the semester. But then lots of organels. So not just mitochondria, but maybe you've heard of the nucleus and the rough endopplasmic reticulum, the smooth endopplasmic reticulum. We're going to review some of those things in the um you have a little review labeling thing to do in the um orientation module, but then we'll kind of quickly go over that on day one um in the face toface classes. And then of course you're sending them to me um via email potentially as well. So those labeled cells, this is just a little review because we don't spend a lot of time on cell structures, but if I talk about the mitochondria or the Golgi apparatus, I just kind of want you to know what that's referring to. You do have a chapter in your book where you can look at some of that, too. But anyway, these all these organels make up our individual cells in the body. And then cells working together to perform a function. So, lots of cells will make up our tissues. And we do look at tissue groups uh in this class. Of course, you have four groups of tissues and they're grouped together based on their um functions and their structure, but cells working together make up tissues. And then each of the organs, now we have to remember this is showing you a stomach and that's what most students think of what's in the abdominal cavity or the heart. They think of those as the organs. I want to remind you or just let you know that muscles and bones, individual muscles and bones are organs as well, right? Because they're made up of tissues that are working together to perform a function. And that's what we call an organ by definition. So tissues working together to perform a function. And most of our organs are made up of several tissues um including, you know, bone. Bone is living tissue. Of course, bones are alive. That means they have blood vessels, they have nerves. Um so not just what we consider what the bone tissue is. So bone connective tissue, blood connective tissue. So lots of things in there. So again organs like bones, muscles, stomach, heart, lungs made up of several tissues. All right? And then your organs that work together make up an organ system. So because this is the stomach, they're showing you here the digestive system. Now systems then working together make up the complete organism. So in this class we do look at each system individually. So you'll see the textbook is uh separated out into systems and we look at those systems separately. But by all means our systems work together. So it's important that as we progress you think about form and function and you think about how systems work together. And so that's one of the the key takeaways that we'll try to um remind ourselves throughout the semester. We want to how does that work together? How does the um cardiovascular system and the respiratory system work together? Um how is digestive system affected by the nervous system? How is the muscular system affected by the nervous system? How is the skeletal system affected by the muscular system? So again, I want to keep I want you to keep that in mind that each system works with other systems. Even though we look at them individually, we do look at those system by system. So keep that in mind. All right. So when we're talking about the organism or any organism, um living versus non-living, how do you know if something's living or it's non-living? So we talk about in this chapter we're going to talk about the characteristics of life and living organisms but you know the difference but how do you know that inherently you could if I you know if I ask students in a face tof face class for example um this table you know is it alive or you know is it living or non-living they automatically know non-living but how do you know that what characteristics does the table have or not have that help you determine that it's non-living? So that's how do we know what characteristics determine determine a living organism from a non-living organism. And these are characteristics we share with all organisms that are living. Okay? So the characteristics of life, that's what we call these. The fundamental characteristics are traits shared by all organisms. And that's how we determine something's alive. Okay? Living. That means that table didn't have these characteristics. We can't often um put that into words, but that's why you knew the table is non-living. So, what is it about it? So, um organization I there's if you look at different textbooks, you're going to have different characteristics of life. Different in that they just have different names. There's multiple ways to discuss this. They all really uh ultimately mean the same thing. So, just keep that in mind. This does follow your current textbook. So organization um this is the interactions of course um between all the parts of an organism. So we looked at that um picture that showed us the different levels of organization and I kind of mentioned you know where we're going to talk about some of those things but the atoms making up the molecules making up the macroolelecules that's organization that is the interactions that have to occur um to have a healthy individual. So between molecules, cells and the organs, all of that collectively is essential to that interaction to for proper function. So when I talked about the systems working together, yes, that's part of the organization that you must have in a human body in order for it to proper function to properly function. Excuse me. But it's the same in plants or bacteria. Any living organism has to have some level of organization. Maybe not as complex uh as animals for example or plants but absolutely there's some level of organization that has to occur. So that is a characteristic of life. So living organisms have to have some level of organization within. And then I mentioned uh previously that ATP is the usable form of energy in the body and that we make that using nutrients we bring in from our diet and oxygen. And so absolutely metabolism is the term. It means the sum of all the chemical reactions in the body. But we're using energy to perform functions in the body and that is your metabolism. So we'll see that ATP which is our usable form of energy that we need. Uh we'll see that throughout um the semester. So ATP adenazine triphosphate. Um again you'll see this throughout and it's just three letters ATP. And then an organism that has uh is considered living. Um an organism has the ability to respond to changes. So your body at the cellular level is monitoring changes both in the body and outside the body. So internally and externally. And then we're adjusting to those changes. So, we typically have a set range of values for things like our blood glucose levels, our blood calcium levels, um your body temperature, all of these things. So, we have a a range or a set point. So, with body temperature, it's a set point. Blood glucose levels and blood calcium levels, blood potassium levels, all of those are in a set range. So, there's a little bit of a high, you know, as long as you're within the range, right? Well, anyway, um monitoring those changes internally, externally, and then making adjustments. So, let's say it is body temperature, the room gets warm, your uh receptors in your skin monitor that change, and they send a signal to the brain. Typically, for temperature, it is the brain. So, we're sending that signal to the brain and uh through the nervous system. And then that value is determined is it high, low. So if it's too high, you're getting hot, then the uh nervous system from the brain will send a signal to, for example, sweat glands to begin to release sweat and then that's evaporation. So as we sweat, that evaporates, that cools us off. And so once that cools us off, we stop sweating, right? So once we get our body temperature back down to normal. So again, that's our ability to respond to changes. That's called responsiveness. And living organisms have that. Now that's an example for humans. You can also think about plants or anything else for that matter. But plants for example, you know, if you set them in the window or close to a window, they're going to grow toward they start to bend toward the light. Correct? And then you kind of turn them every once in a while so they don't just continue to bend in that direction. But if you turned it, it's going to bend again toward the light. So again, they're uh responding to they need that light to produce um the food that they need and so they're going to move toward that light. So another example of a living organism and we'll be talking you know going through these as we progress as well. So three more growth is referring to so organisms that are living should have the ability to increase in the size of the cells that they have or in the number of cells. So when you have a growth of a cell or growth of the number of cells um that is happening only in living organisms. So uh for example um let me think well during growth and development in the human body of course you are growing the number of cells. Another example we'll see throughout the semester and when we study the blood you know the size of the cells will change as we go through the steps to develop blood cells. So um arythraittes for example uh or um any of well lymphosytes they do grow in size to a certain extent. Now interestingly enough things like our platelets that cell is really large and then it breaks down into small pieces and that's how we form platelets. So growth and then of course they end up being smaller at the end. That's showing um that it's a living organism if you can show growth is occurring. Development involves growth but also differentiation. So this is talking about the fact that cells can grow but also differentiate. So the example I used of the ariththraittes and the lucasytes. So the red blood cells and the white blood cells andor the platelets those are the thrombocytes. As they grow and develop they change. So you start out with an immature arythraite for example it has a nucleus but then it differentiates it becomes specialized to carry out its function of carrying oxygen and so in that process we get rid of the nucleus. So that is that change that occurs. So differentiation is the term that means specialization changing from a immature cell that's not ready to function to a specialized cell that is ready to function. It's a mature cell. So that changing of the cell um through several stages usually is called differentiation. So while the red the red bone marrow produces that red blood cell the cell that it begins as that's not ready to function yet. It has to differentiate. So we have growth and development that does occur before those cells are ready to function. And then reproduction formation of new cells or the new organism altogether. So for us in humans we know that requires the oytes in the female those are the egg cells in the female and the sperm cells in the male uh to form new cells and to form new organisms. So for reproduction of the whole organism that is specific to those oytes and spermatocytes or sperm cells for us. All right and again these are the essential characteristics of life. uh not only humans have this of course all living organisms uh represent these six characteristics or have these six characteristics that table did not have these characteristics and that's how you knew inherently you you did know that that was a non-living um organism. What are the basic needs of a living organism? This isn't covered in your textbook but this is something that we should um discuss just a little bit. Um, all living organisms including humans need some basic things. So for the maintenance of life, that's what that just says at the top, maintenance of life. You do need some specific requirements. You have a requirement of water and food, which you guys probably already knew that. Um, but also oxygen. We have to have oxygen. And then heat. So um, heat in that, um, we actually produce heat, uh, during our metabolism. And so at the cellular level, chemical reactions that are occurring can produce some heat. Uh and then of course uh we need a certain amount of body temperature to remain alive. So you know if your heat uh your body temperature drops too low, hypothermia uh you can start losing you know digits things like that but you can die from hypothermia. So again we have to have that heat. Now this is just showing you the term temperature means something else. So that term uh temperature means the measure of the degree of heat. So body temp is a measure of how much heat we have in the body and we can generate some of that heat ourselves obviously muscle contractions how we're doing some of that. All right. And then pressure. So atmospheric pressure hydrostatic pressure important both for human beings but other organisms as well. And these are the requirements that we have. So atmospheric pressure and hydrostatic when we start looking at the cardiovascular system hydro means water. So we're made up mostly of water blood pressure right hydrostatic pressure is contributing to our blood pressure and we do have to have a certain u blood pressure to transport uh that blood throughout the body and it carries lots of important things for us as we'll discover in this class. So, not only the quantity of all of these uh requirements, but the quality is important, and that's probably pretty easy to understand when you look at things like water. If you're drinking contaminated water, it's probably not going to be beneficial to you. Um, so things like that. So, um, I've probably talked a little more than usual. I did start this out, um, because this is the first chapter. I promise that I won't, um, talk so much at the beginning of the chapter. uh lectures for the other chapters. I'm just trying to get everybody used to what you're doing here. But the last part of the lecture for chapter 1 has to do with homeostasis. And so by definition, homeostasis is of course maintaining that stable internal environment. And we do that by resisting change. Now we have change is constant in the body. So whether it's the environment you're in or you're drinking coffee or you know whatever you're doing you're getting up moving around those are all creating changes in that internal environment for example and so we try to maintain a balance or stable internal environment by responding either responding to the change and or trying to resist that change. So we're trying to maintain equilibrium in the body. We don't stay at equilibrium. It's constant. We're being bombarded by variables constantly. Like I said, getting up and moving around, you're changing your position of the body. You're changing your external environment going outside into the heat, coming in uh to the cool air, ingesting things, etc. So to try to maintain this stable environment and resist some of these fluctuations that are occurring, we have uh control systems in place. So we have receptors. We mentioned um receptors in the skin earlier when we talking we were talking about responding to external temperature but we have receptors throughout the body that are monitoring these changes. We have a set point or I also said a range that's another way to say that some things are set point like the body temperature. Your blood pH is at a set point. You don't want to vary around that set point very much at all or you'll become sick. Uh and then other things like your blood glucose levels um those are in ranges. And then we have aectors. Aectors are the uh when we're trying to um maintain the stable environment, resist the change that's occurring, we send out signals toectors. So in the scenario I used earlier, our aector was a sweat gland. We sent out a signal to the sweat gland to tell it to start releasing sweat so that it could evaporate and cool the body. So that's the aector. Whatever organ you're having an effect upon is one way to remember that. Oh, sorry. Um, okay. So, in this visual aid, and I don't I think this is not in your textbook anymore. Um, so make sure you see this one here. And I did add to it. So, um, this is looking at if you look at number one, some stimulus produces a change in a variable. So, if we use the body temperature example again, it's that room temperature that you're in. Okay? So, or maybe you stepped outside the environment. So, external environment, the heat is the stimulus. uh produces a change in the variable. So it's causing your body temperature to rise because you're in a hot environment whether it's inside the air conditioning is not working or you've stepped outside. So then that causes an imbalance and you can see that they're using a teeter totter to kind of represent. So we want to stay at homeostasis. Something has caused a change in that caused this imbalance. Then we have receptors that respond. So they're monitoring this change. Oh, they're going to take this message to the brain. So receptors can be simple or they can be very specialized. They're monitoring depends on the system they're in. They're going to send this information through the nervous system. So this is sensory information. It's going into the control center which is typically the brain. So I added the brain up here. It's not always the brain but the majority of the time it is. So this word aphrant means into always. Afrant pathway sensory information, sensory neurons are carrying information always into the brain and spinal cord. So that's why it's called the afrant pathway. The term afrant always means into and you'll see this throughout the semester. So number three says information sent along the afrant pathway to the control center in the brain. So then uh body temperature uh is being you know determined is this too high or what? So when it goes in the control center, decision is made and output happens. So information through the nervous system. This is usually motor information, motor ner neurons, excuse me. Um, same thing, but motor neurons coming out. So sensory neurons carried information into the brain and then a motor neuron is going to carry it out. So ephrit, you may have already guessed, ephrant always means out of. So we're going to see this in different places, not just the nervous system. Lymphatic system for example aphrant means into ephrant means out of. So motor information coming out it's going to cause something to happen. So the output is information sent out to the aector. The scenario we used uh the aector would be sweat glands. So then the response of the aector feeds back to uh reduce the effect of the stimulus. So we had a rise in body temperature. We stimulate our sweat glands to release sweat. By the way, this is not the primary way we get rid of heat from the body. Just letting you know. Um, but sweat glands release sweat that evaporates. That's evaporation to cool the body, brings it back down hopefully um to normal range. And then that would take us back to homeostasis or equilibrium. So, we would stop sending that information into the brain and stop stimulating the the uh sweat glands once we have cooled the body back. Okay. Now, you can see how if you remained in a really high heat situation and you kept sweating that eventually you could, you know, become dehydrated, right? If you're not replacing some of the water you're losing because we're evaporating the water to cool the body. You know, that's where people get in trouble with dehydration. So, anyway, you can make some of those connections there. But, this is a nice little visual aid to help you remember what's happening. You've got receptors, control center,ectors, um, functioning to help maintain homeostasis and that's what our body systems are doing constantly trying to maintain homeostasis. So negative feedback systems um, negative feed so we have two ways to help maintain homeostasis and uh, we have two feedback mechanisms. Negative feedback systems reverse a change in a controlled condition, which is what we just did with the body temperature. Another example is regulating our blood glucose levels. When we um eat something that is high in carbohydrates, then we're going to have an increase in our blood glucose levels. If it goes outside of our normal range for glucose, then receptors, chemo receptors are monitoring that. They send that information into the brain and then we send a signal out um for the glucose to be removed from the blood and we do this by sorry send a signal to the pancreas to release um insulin and pull that glucose out of the bloodstream. So again u we're monitoring and going to reduce that um blood glucose level back to normal. So we store that glucose. We remove it from the blood and store it for later use. Positive feedback systems on the other hand. So by the way the majority of our body systems function through negative feedback mechanisms meaning that you reverse a change that's happened in a control condition. Then we do have a few um systems that function through positive feedback. This is typically happening um either special circumstances we're going to see like pregnancy or when you've had some kind of trauma to the body for example. It's not the only examples but that you know that's a couple of examples. But positive feedback systems function to reinforce a change that has occurred. So the change has occurred. We're not going to stop it. We're going to help that change. We're going to make it continue. So example with the uh child birth once um the uh muscles in the uterine wall are you know they're stretched of course and it's about time for child birth to occur we start having contractions. Those contractions of that muscle then send a signal to the pituitary gland to release a hormone called oxytocin. Oxytocin then travels to the target is the muscles in the uterus and causes more contractions to occur. So that's a positive feedback system that is reinforcing that change to help with that child birth. Okay. The other example and we'll talk about this one later in the semester as well is forming a platelet plug. So for blood clotting. So we have a break in a blood vessel that's going to go through a series of changes to create a platelet plug. So platelets become sticky and they start sticking to each other. Red blood cells start sticking to them. They form a platelet plug. We don't want to stop that change. We want to help reinforce that change until we we actually create a clot that stops the the bleeding. So positive feedback is going to those as the platelet plug starts forming those platelets become sticky. They are going to continue to have more platelets become sticky. So positive feedback until we get that clot formed to block the the blood vessel um bleed. If you know that's going to happen obviously in some major traumas that's not going to happen but this is the normal in this class. Remember we do look at what's supposed to happen. How does our body take care of us? Uh what's the normal response? We do look at a few conditions where you know this is um happened in the body. We try to fix the problem but we can't. So hemorrhaging, for example, is something where we increase our heart rate to try to get more blood flowing, but if we've got a hemorrhage or a big break, excuse me, increase in heart rate just causes more blood to pump out the break. So again, we're not always, that's why we have doctors and nurses and hospitals. The body can't take care of it itself. But in this class, we're looking at what's supposed to happen so that when you go into those programs, you can go like, "Oh, I know how it's supposed to work. Now I'm going to apply like now it's not working." what what do I need to do to help the body for example so many of the body's um and again I said this already but many of the body's homeostatic controls are negative feedback mechanisms so the majority are functioning through negative feedback we do have a few things happening with positive feedback so what's an everyday example so we talked about the body but also you can see this in the world around you too so you know anatomy and physiology is not that different from other mechanisms, mechanics, um you know the things that the machines are doing etc. So everyday example of negative feedback um often in a textbook they'll use the thermostat in a room. So it's set at a certain temperature and when you get above that temperature in the room so it's monitoring what's happening. That's your receptors. the temperature goes above, let's say the thermostat is set at 70 and it creeps up to 71, 72, it's getting warmer than 70 in there, then that sends a signal to the, in this case, air conditioning to turn on. That should kick on and when it brings the temperature back down to 70, it'll kick off. And the same thing for heat. Um, but you can see these things um in multiple areas. So each individual uses homeostatic mechanisms to keep body levels within a normal range. Normal ranges can vary from one individual to the next. So we do study um set points of things, but it is important that you know your own normal range or your set points. So for example, blood pressure. We're going to study and we're going to look at the fact that size of a person does affect their blood pressure. So a very large person is not going to have the same blood pressure on an every you know everyday basis as a very small person. Um and that's just the nature of the difference in the individuals. So we what we study in our textbook by the way this is what's occurring in 60 to 70% of the population. And when it comes to certain things like the shape of the stomach, you know, we're talking about the organ, the stomach, not the belly, but the shape of our organs or, you know, how many sections to that muscle we have, there can be some variation in the population. So 60 to 70% of the population will have exactly what we see in the textbook. But then remember, there's always outliers and there's always some variation in that population and that's okay and you should expect those things. Um, and then the same thing is we don't all have 120 over 80 blood pressure. And um, you know, that's why you want to know what you're what's what's normal for you. And so even if you're on blood pressure medication, you may never you may not get down to 120 over 80 exactly. And that may not be the goal. So again, individually, it can vary from one person to another. All right, that's the end of the lecture material for chapter 1. you can see in your textbook that takes you through a couple of pages and you do have some different uh visuals. Uh so for example, figure 1.4 in your textbook um does have the um positive feedback. And I do apologize. I try to stay away from numbers a little bit because if the textbook changes something, it might not be 1.4. But look for a figure for uh positive feedback example as well as negative feedback. There's one on the page before that. So you do have some examples, some visual aids for positive and negative feedback mechanisms and they will differ. You know, sometimes your pictures will differ from mine and that's just meant to give you uh additional, you know, study tools. So keep that in mind. So that's it for chapter 1 for lecture. The rest of the chapter 1 material will you'll utilize that as a resource when you're working through your lab for lab one in the lab manual. So, you use the textbook chapter 1 and you can see that in your schedule for the lab manual lab one activities um the prelab for example where you going to look up those words from chapter 1 or your index uh glossery in your textbook. Reach out if you have questions about this material.