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Biology: Animal Tissues: Loose Connective Tissue


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About this Lesson

  • Type: Video Tutorial
  • Length: 13:44
  • Media: Video/mp4
  • Use: Watch Online & Download
  • Access Period: Unrestricted
  • Download: MP4 (iPod compatible)
  • Size: 148 MB
  • Posted: 07/01/2009

This lesson is part of the following series:

Biology Course (390 lessons, $198.00)
Biology: Animal Systems and Homeostasis (63 lessons, $84.15)
Biology: Intro to Animal Systems and Homeostasis (6 lessons, $18.81)

Taught by Professor George Wolfe, this lesson was selected from a broader, comprehensive course, Biology. This course and others are available from Thinkwell, Inc. The full course can be found at The full course covers evolution, ecology, inorganic and organic chemistry, cell biology, respiration, molecular genetics, photosynthesis, biotechnology, cell reproduction, Mendelian genetics and mutation, population genetics and mutation, animal systems and homeostasis, evolution of life on earth, and plant systems and homeostasis.

George Wolfe brings 30+ years of teaching and curriculum writing experience to Thinkwell Biology. His teaching career started in Zaire, Africa where he taught Biology, Chemistry, Political Economics, and Physical Education in the Peace Corps. Since then, he's taught in the Western NY region, spending the last 20 years in the Rochester City School District where he is the Director of the Loudoun Academy of Science. Besides his teaching career, Mr. Wolfe has also been an Emmy-winning television host, fielding live questions for the PBS/WXXI production of Homework Hotline as well as writing and performing in "Football Physics" segments for the Buffalo Bills and the Discover Channel. His contributions to education have been extensive, serving on multiple advisory boards including the Cornell Institute of Physics Teachers, the Cornell Institute of Biology Teachers and the Harvard-Smithsonian Center for Astrophysics SportSmarts curriculum project. He has authored several publications including "The Nasonia Project", a lab series built around the genetics and behaviors of a parasitic wasp. He has received numerous awards throughout his teaching career including the NSTA Presidential Excellence Award, The National Association of Biology Teachers Outstanding Biology Teacher Award for New York State, The Shell Award for Outstanding Science Educator, and was recently inducted in the National Teaching Hall of Fame.

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Recent Reviews

loose connective tissue
~ Jenny6

all day I have been trying to find a video on the internet to help explain connective tissue in the thank you very much!!!................I really liked it.

loose connective tissue
~ Jenny6

all day I have been trying to find a video on the internet to help explain connective tissue in the thank you very much!!!................I really liked it.

Are you remembering something? Are you remembering that in order to maintain homeostasis in a multi-cellular organism you need to specialize? Because if you're remembering that, you're right on. The bottom line is that as multi-cellular organisms got thicker and put their cells further and further from the environment, cells had to take on specialized jobs. I also hope you're remembering that there are four basic types of tissue.
Now we want to talk about a different type of tissue--a tissue called "connective tissue." Now, connective tissue, I've got to tell you, there's not much fancy about this. Guess what connective tissue does. I'll bet you said, "connects." Well, you're partly right. That is one of the jobs of connective tissue. Now, here comes a theme. During this whole talk I want you to remember something. There were four types of tissues: epithelial tissue, which I'm sure you know all about--the skin, the linings, everything else--epithelial, connective--remember that one for a second--muscle and nerve. So epithelial, muscle, nerve. Everything else is connective. What about blood? Connective. What about cartilage? Connective. What about bone? Connective. So it does a lot more than connect, but connecting is something it does.
Let's talk a little bit about why connective tissue is different. Epithelial tissue, if you recall, is something that was all cells. I mean, it was mostly cellular. On the other hand, connective tissue is not mostly cellular. In fact, it is mostly acellular or extra-cellular materials. Does that mean there are no cells? No, there are cells, obviously. This is a tissue and cells together make tissue, but it's mostly extra-cellular material. Now, we call those extra-cellular materials "the matrix," and a matrix--I always think of a matrix of something like concrete in a sidewalk. The concrete is the matrix and the steel rods going through the sidewalk is the not-matrix. The matrix consists of this kind of like gooey material--now, you can't write "gooey" on an essay. It's kind of a gooey material but we have a name for it and that name is called the "ground substance." See, you thought biologists always made up big, long names just to make things hard. No, it's called the ground substance. The other stuff that's in this matrix is protein fibers. Fibers are big in connective tissue. Well, where are the cells? Well, I said it consists of two things. One, matrix; two, cells. I want to talk about the cells because they are the things that are going to specialize, and they're going to give the jobs to the different types of connective tissues, so if you get those, everything else will be easy. So let's take a look at the different types of cells, and mostly let's talk about what they do. I'll give you names later, okay?
First of all, let's take a look at the functions of connective tissue in general, besides connecting. Well, we'll start with connecting. The first thing that connective tissue does is it forms a structural framework for the body. So later on when we start talking about bone you'll think of structure and solidity and holding yourself together--that's connective tissue. Second thing--it transports. It transports fluids. So the second major function of connective tissue is not connecting, but transporting fluids and dissolved substances. A third thing is protection. Like epithelium, there are some things, for example, like brain, that needs to be protected, so I have bone to do that. That's a type of connective tissue that we'll see later. A fourth function--it does what we call "tissue-tissue support," tissue to tissue support and communication. So I'm going to link these two things. So, for example, when one tissue is connected to another tissue, say a muscle to a bone, that's going to be connected by connective tissue.
One of the things it does is it stores energy. You may have heard of fat. I've been working on that over my life, just trying to store that stuff because it's so crucial to life. Defending the body is number six. The whole immune system, pretty much, is connective tissue. So defending the body, and remember what I said--if it ain't epithelium and if it ain't muscle and if it ain't nerve, it's connective.
I want to show you the generic connective tissue, and we call that "loose." It's the first type of several types of connective tissue. It falls under this lump term of what we call "connective tissue proper." Why "connective tissue proper"? Do you think there's connective tissue improper? No, but it's pretty much saying it's the generic connective tissue. And the first kind of connective tissue proper I want to tell you about is called "loose connective tissue," otherwise known in anatomy and biology textbooks as areola connective tissue.
This is a good starting place because it is kind of a generic thing, and it's got just about everything all the other connective tissues have it in, but they're going to have these things in different ratios. So we're going to really work a lot with this diagram right here. Here is a schematic, an artist's representation. Now, where would I find something like this? This is a connective tissue. It's probably the most common connective tissue in your body. It's the space-filler in your body. You know, you don't have a lot of air pockets in your body. Why? Because your stuff's connected. My skin is connected to my muscles and bones by this type of connective tissue, so let's see what it has in it.
First of all, we said that there's ground substance, the matrix, and if you just look at this white material in here, that's going to be your ground substance. Now, within the ground substance we said there would be fibers, and you see that there are probably two types of fiber in here. There are, at least for our diagram, we have these very kind of tough, strong, thick fibers made out of a protein called "collagen." Collagen is probably the most common protein in the animal kingdom. It makes up all other connective tissues--it's in all of your connective tissues, and it literally holds you together. Now, there's another type of connective tissue that we've shown here as the thinner ones, and that's an elastic fiber. So we have fibers that are tough and fibers that are elastic. Those are going to be important. There's even a third type of fiber that is a collagen relative that we haven't put in here but may come back and talk a little bit about it later called a reticular fiber. It's made out of the same subunits that collagen is, but it networks more, and since it networks more it's called "reticular fiber," and that's going to like just hold on to things. You'll see that later. But it's pretty much biochemically collagen, just organized differently.
Now, what makes these fibers? Well, anytime you see the word "blast" at the end of a cell it means "creator of." There's a group of cells in here called fibroblasts. Now, fibroblasts, guess what? Make fibers. So if we think about a fibroblast and what it would do, we could simply say that a fibroblast is going to be the thing that is going to make the collagen fibers, and they're going to make the elastic fibers. We'll call that a fibroblast right there.
White blood cells--a lot of them floating around your body. You know what? People think white blood cells are in your blood. That's why they're called blood cells. Well, guess what? They're everywhere. They crawl around. They're looking all the time. There are several different types of white blood cells. Some of these are free and some of them cruise, and we call these macrophages--big--phage means eaters. These are phagocyte white blood cells. They engulf foreign materials that come into your body. So that would be a macrophage, these big old green guys here.
Another one that's an important type of cell is called a "mast cell." A mast cell is going to be--did you ever hear of antihistamines? Antihistamines are drugs that fight a chemical called histamine. Histamine is a chemical made by mast cells. Mast cells and histamines make your membranes leaky. That's why when you get a cold, you produce more histamines because you want leaky membranes so that the white blood cells can't get in there. So what do you do to treat your cold? You take antihistamines. Go figure. Not a lecture on medication, but I just had to do that. So let's talk about mast cells. Mast cells make histamines. That would be one of those.
A few other cells. See this yellow one right here. That's an adipose cell. An adipose cell stores fat. We'll talk more about fat later. Little cells--look at these guys. I'll do this one first--brown. That is called a melanocyte. Did you ever hear of melanin? Melanocyte. Melanin gives you pigment in your skin and it's also found scattered throughout your connective tissue, too. It's also obviously in some of your epidermal cells. And last but not least, a group of small cells called, mesenchyme cells. Now a mesenchyme cell is a very important kind of cell because it's a cell that's referred to as a stem cell. Stem cells are getting big attention these days. There are a lot of different types of stem cells. The different types of stem cells give rise to other cells. So this particular type of stem cell is what's going to be the precursor to the fibroblast or it may also give rise to a macrophage or a variety of other cells. We call those cells the etcetera cells.
There are so many cool different types of cells in here. Let me tell you about one more--different types of connective tissue. I want to talk to you about a type of connective tissue that has a lot of those adipose cells in it. What did I say an adipose cell was? This is a second type of loose connective tissue proper. And this particular type if tissue is fat. You know, a lot of us fight the battle of the bulge. Did you ever notice that the first time you gained weight it was like really hard to do? You can see that these fat cells are mostly yellow, and inside of them they just have this small nucleus and not much cytoplasm, and here's why. Yu see, under your skin is a layer of fat. Fat is actually stored in cells, and so this would be an example of adipose tissue. The first time you gained weight it was really hard to do. Why? Because you had to add fat cells. But then what did you do? You lost the weight, but did you lose the cells? No, you did not. Since you didn't lose those cells, it was just real easy to refill them. So that's adipose tissue.
There are a couple of other kinds. There's a type of tissue called "reticular tissue," which is found in the reticulum. It's going to form a network, and that's going to be found in your spleen and liver. That's another connective tissue proper. Now we're really going to get into the connective types of tissues, but that's going to be a topic for another lecture.
Animal Systems and Homeostasis
Introduction to Animal Systems and Homeostasis
Animal Tissues: Loose Connective Tissues Page [2 of 2]

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