Human physiology is a one semester course during which time we will go through all of the major organ systems in the body. We will start off by reviewing or perhaps learning for the first time some cellular physiology. And then once we are grounded in that information, we will then go ahead and jump into learning about specific organs and structures within the body and how they function. This class is one that as we work through the semester, each... topic that we learn typically is building upon the information that we have covered previously.
So perhaps unlike other classes that you had where material can be broken up into different units and they are disjointed or unrelated, everything we talk about this semester will build upon previous information. So it's interesting that in reality perhaps by the time we get halfway through with the semester you will have learned all of the basic physiologic principles that you need to know, but as we learn different organ systems, it will be those same principles that are applied to a different organ system. So it's real important that you are keeping up with material.
If you fall behind, it's very difficult to catch back up. So be sure as you're preparing for our class time together that you're coming having reviewed your lecture slides prior to class. Review them on your own. and then when you come to class what we will do is we will use that time to review concepts to make sure that your understanding is correct.
My goal in this class is that you will learn this material and be able to apply this material. So application is the key. Simple regurgitation of content will not get you very far in this class. You need to make sure that you understand this content at a level that you can actually apply it when it is presented to you in a bit of a different way than what you're used to seeing.
So we're going to start off with first being introduced to this term. homeostasis. This was a term that was coined by Dr. Cannon, and what he was describing with this term is the body's ability to maintain a relatively stable internal environment through a variety of physiologic responses. So what we'll see is that as we're studying physiology, studying physiology is actually understanding the intricacies of how we maintain homeostasis. This slide shows some various factors that are constantly being monitored by our body.
This is not a slide that you need to be memorizing these numbers. The purpose of this slide is just to give you concrete examples of some of the things that are body is constantly monitoring. So all of these variables are things that have a relatively tight range that we need to keep within.
If we get outside of that range then that would signify some type of pathogen. pathology, some type of disease process. So our body is constantly working to try and keep these things within a normal range. Now one way that we can picture how homeostasis works is to imagine the state of homeostasis being a state of balance. I've indicated that by our balance at the bottom of this slide.
So in order to maintain homeostasis, we have to be constantly monitoring what's going on within our body. So we have receptors that we'll learn about, and these receptors are monitoring. for change.
They're going to take this information that they're receiving and they're going to send that information to the integrating center. If everything is within normal ranges, then the integrating center will just keep on rocking along, keeping things functioning as normal. However, if the integrating center receives information signifying that something has moved out of the normal ranges, then it's going to send information to effector organs. And it's the effector.
then are going to bring about changes to bring us back into balance or to bring us back into homeostasis. Now a simplistic way to look at this is again to think of this idea of homeostasis as being in balance. So if we have some type of change that occurs that causes imbalance, then that's going to cause our scale to tip. So in this example, this red circle just simply indicates that something has changed.
Something has thrown our system out of balance. balance. So there's basically three different ways that our body might respond to that.
One is, is it may simply just get rid of the thing that has caused the imbalance, thereby bringing us back to level. In other situations, we may see that our body will work to create another substance, a response that's basically going to counterbalance what initially threw us out of balance. And then the third way is basically a combination of of these two by getting rid of the initial problem to some degree, and then perhaps if we're not completely in balance, producing another response that's going to bring us back into balance. So as we go through these different organ systems, one thing to constantly think of is that our body is constantly going to be working to try and maintain balance or maintain homeostasis.