Levels of Organization

As you go through this course, you're likely to realize that you're learning things at all sorts of different levels from the molecular, all the way up to the whole organism. We're gonna go through those levels now and we're gonna use this diagram to do so. Now I realize this may look a little convoluted. Don't worry, we're gonna take it step by step at the smallest level. We have the atomic and the molecular level. This is really the chemistry of the body. Don't worry, you do not need to be an expert chemist to do well in this class, but you do need to know the basics to understand how the nervous system works. For example, you need to understand the properties of ions early on. In this course, you're gonna be responsible for knowing some of that material, but there's a view chapter to get you up to speed. If you need it as we move up, we're gonna reach the macromolecule level. The macromolecule level is the biochemistry of life. The large biomolecules, things like proteins and enzymes, lipids, DNA, and RN A. Again, you do not need to be an expert biochemist to do well in this class, but you need to know the basics. A lot of physiology is based on how enzymes work or how molecules interact with lipid bi layers. Again, you are gonna be responsible for some of this material in this class. But early on there's gonna be a chapter that reviews it to get you up to speed if you need it. As we move up a level, we reach the cellular level, the cellular level with all the organelles and all the cell parts, we usually call the basic unit of life. And we say that because we usually say that nothing smaller than a cell is alive and you are alive because you're made of trillions of cells. The cell is the smallest thing that performs all of life's functions. Again, you're gonna be responsible for understanding the basics of cellular function and cell parts. But early on in the course, we'll review that material and get you up to speed if you need it. If you study anatomy and physiology at the cellular level, we say that you are doing cytology and being a psychologist is a career that you could pursue. Now, as we move up, we're gonna reach the tissue level. And this is probably the first level that you're gonna study in a way that you've never seen before. The tissue level is when you take groups of cells that are all doing the same thing, put them together and they're performing a common function. Now, when you study anatomy and physiology at the tissue level, we say that you are doing histology, there's only a few types of tissues in the body and the different little tweaks that you make to them and the different ways that you put them together, you can create different organs, the organ level we're going to define as groups of tissues that are bound together, working together to perform a common function. Now, you have lots of organs in your body, but of course, they don't work on their own organs, work in organ systems. We're gonna say that an organ system is a group of organs that are working together to perform one common function. Now, the organ system level, that's how we're going to break up a lot of this course, chapter by chapter will be one organ system and then often the next chapter will be a different organ system. Of course, no organ system works completely on its own. When you put a bunch of organ systems together, you are going to reach the organism level that's gonna be you and people like you. Now, you'll notice that I have this bracket around these largest levels here. This bracket represents the study of gross anatomy. Gross anatomy is study of anatomy that you don't need a microscope for things that you can just see and dissect. If you're taking an anatomy lab or you're doing dissections, that's probably a gross anatomy lab. Now gross here means this larger scale. But you can remember it because if you're taking a gross anatomy lab, you're doing dissections, things may squirt on you. Some people think that's gross. Be careful an important thing to remember. We've been talking about the structure function relationship. This structure function relationship is going to exist at all levels of organization. Why do enzymes function the way they do they function the way they do because of the way they're structured. Why do organ systems function the way they do they function the way they do because of how they're structured. And also it's important to remember that all levels of organization are connected. A change at the macromolecule level is gonna have ripple effects all the way up to how organ systems function. If you change the anatomy of an organ system, that was gonna change a lot of things in the body and it will ripple down and could even have effects down to the molecular level. So as you're learning this material, remember the structure functioning relationship works at all levels. All things are connected, the more you integrate this stuff together. Remember that all these levels, all these connections exist, the more you'll understand this material in a rich and important way with that. We have another example below. Practice problems to follow and I'll see you in the next video.

The example tells us that statins are some of the most prescribed medications in older adults. And then it tells us that the following statements explain how statins work. So there's gonna be 1234 statements. And then we have two questions. A at what level of organization do statins work most directly? And b what other levels of organization do statins affect physiologically. So keep those questions in mind as we go through these statements. First off, we have statins share a chemical similarity to the molecule. HMG Coenzyme A leading them to inhibit the enzyme. HMG coenzyme a product base. All right, inhibiting an enzyme sharing a chemical similarity that seems like it's happening at the molecular level or maybe you could say macromolecule level. But all right, molecular for now, uh the next statement says inhibiting HMG coenzyme reductase lowers overall cholesterol production in the liver. All right. Now, we're talking about how an organ is functioning. That's another level. Next, it says lowering cholesterol production in the liver leads to lower blood cholesterol levels and less plaque formation on artery walls. All right. Now, we're talking about whole different parts of an organ system blood and artery walls and how plaque formation comes about. And then finally, we have reducing plaque formation, reduces the risk of death from heart attack, stroke and other causes. All right, I can't think of anything that affects the whole organism more than death. So I think I'm gonna say at the end, it affects the whole organism. So at what level does it seem to work most uh directly, I'm gonna say molecular, right? It's inhibiting an enzyme. But what other levels does it affect? I'm gonna say all of them, right? We talked about the liver, we talked about a whole organ system, blood and blood vessels and artery walls and then we're talking about death, something that definitely affects a whole organism. So this relationship between different levels is really important to remember as you go on. Yes, you can focus on studying a a specific level. Some people are molecular physiologists, people, some other people do more gross anatomy, but all of these levels affect each other and are intertwined and are really impossible to completely separate. So with that, we have a few more problems below and I'll see you in the next video.

Given the following 5 levels of organization, which represents the correct hierarchy from smallest to largest?

A) Tissue B) Organ C) Molecule D) Cell E) Organism

• A. A, D, C, E, B.
• B. B, E, D, A, C.
• C. C, D, A, B, E.
• D. C, A, B, D, E.

Which statement about the levels of organization in anatomy and physiology is most correct.

• A. To understand any other level, you must be an expert in atoms & molecules because they are the most basic. 
• B. The molecular and organ system levels are most closely related.
• C. Changes to anatomy or physiology at one level are likely to affect function at many other levels.
• D. People who study whole organ systems are unlikely to need to understand the behavior of atoms.

During a cancer screening a doctor may choose to screen using histological or cytological methods. Cytological methods are often less invasive than histological methods. Why do you think this may be?

• A. Histology usually requires intact tissue gathered from a biopsy or dissection, while cytology usually looks at individual cells which can be collected without greatly disturbing the entire tissue.
• B. Histology often requires imaging of the whole body, while cytology requires an external exam of the body without any imaging tools.
• C. Histology involves surgery so that whole organs can be examined, while cytology can be performed using genetic or molecular analysis of bodily fluids such as saliva or urine.
• D. Histology requires removing and analyzing single cells from an intact tissue, while cytology can be performed using imaging techniques such as MRI and therefore does not require removing cells or tissue from the body.