Understanding Connective Tissue Functions and Types

Okay, we're going to continue on with chapter four, and we're going to begin to look at another tissue or type of tissue that is called connective tissues. Now, connective tissues are going to be organized as being cells that are surrounded by a substance we call the matrix, extracellular matrix, because it's outside of the cells. Now, this matrix is going to consist of... a type of fluidy substance that we call the ground substance and within this ground substance we're going to find fibers. Now these fibers are going to be composed of different types of protein. The connective tissue is going to be very broad in its spectrum for its functions and also that's going to show up. in a great variety in its structures. So connective tissue in our bodies is going to help serve as a structural component. So it's going to be considered part of our skeletal system. It's going to be involved in transportation of moving things from one area of the body to the other. Protection of our organs and parts of our body and connecting them. We store energy in connective tissue. It's also going to be involved in their immune system and defending our bodies against pathogens. Most connective tissue is vascularized. Now cartilage we will find out really isn't. But the whereas the epithelial tissue is avascular, the connective tissue does have a blood supply. And there's also going to be sensory function associated with this connective tissue as well. Let's look at that extracellular matrix. Okay, it's this substance that's going to surround the cells, and it is going to include what we refer to as that ground substance, and it has fibers within it. So the ground substance is this colorless, yet viscous. fluid that we would find surrounding the cell. So here's our phospholipid bilayer, the intracellular environment, our extracellular environment. What we see is the extracellular matrix here is surrounding it, and it is not just devoid of any components. It's going to have very specific structures associated with it and molecules as well. And in fact, The characteristics of the tissue is going to vary according to variations in this extracellular matrix. The particular nature and properties of the components within this matrix make each connective tissue different. We can see here the fibers and we can see glycoproteins. Now the different types of connective tissue that we're going to look at are going to be either referred to as connective tissue proper which can either be of the loose variety or dense and this is going to be based on the organization of the substances within the connective tissue now the next type of connective tissue is going to be the fluid connective tissue The fluid connective tissue is going to be when you have your cells surrounded by the matrix, but the matrix is going to be a fluid system. And the supporting connective tissue is going to be the type of connective tissue involved in providing structure for our body, such as the bones. And what we're going to see is a change in the number of cells and we're going to see more of the matrix with the fibers. Now in the connective tissue we're going to see different types of fibers. So the first and most common types of fibers that we are going to see are the collagen fibers. This is made of the protein we called collagen. These collagen fibers are very strong so they provide strength to the particular tissue that they are included in and to some degree some flexibility. So the collagen fibers are going to provide strength and resistance when pressure is placed on this tissue. one direction such as compression in a vertical plane. We find collagen fibers in tissues such as our tendons and ligaments. Tensins are going to connect muscle to bone and ligaments are going to connect bone to bone. Now another type of fiber that is going to be made of the collagen protein also are the reticular fibers. Now they're organized differently than we saw previously. The reticular fibers are going to create more of a network, almost like a mesh. And we call this the stroma. And we find this in organs such as our liver and our spleen. And this stroma is going to provide support for the functional component of those particular organs. And the functional component we refer to as the parenchyma. Now because of the organization of these reticular fibers in this mesh-like network, it's going to be able to absorb forces coming at it from many different directions, not just one plane of direction. And we're also going to see these type of fibers present in certain organs that have the surrounding tissue called the sheath around it that's going to be protective. Now another type of fiber that we will find is called elastic fibers. This is going to include the protein we called elastin. And as the name would imply, this type of fiber allows the property of being able to stretch and then recoil back into its original shape. This is just an illustration of a histology slide. showing these different types of fiber and we're going to look at these in the lab. These rather translucent fibers here, these are the collagen fibers. These have stained very nicely. It's almost like you can see through them. Now the darker thin lines that look like a hair may have fallen across your slide, these are the elastic fibers. made of the protein elastin. Now what we see these dark spots, these are going to be representing cells. Here we see a fibroblast. The fibroblast we'll look at are the cells that actually create the proteins that generate the fibers and a macrophage. And those are an immune type cell that are going to help clean up debris. Now The cells that are present in the connective tissue are a variety. So we'll just touch on each of these. So remember, the connective tissue is going to be cells surrounded by a matrix. So we see the first type of cell, the most common type of cell, are these fibroblasts. So here's a picture of fibroblasts. These are going to secrete the proteins that are used to make the fibers. Now the second most abundant type of cell that we find are fibrocytes. Now the fibrocytes are going to be involved in maintaining this connective tissue. We may see a certain type of connective tissue have cells called adipocytes. These are really just fat cells. This is a picture of adipocytes over here. We can see each of these is a cell. And what we see is the boundary of the cell membrane in pink. And the white part in the center may appear empty or clear, but it is actually a vacuole area that is filled with fat. So it's a fat droplet within this fat vacuole. Now we may also see stem cells which can regenerate and replace tissue that is being repaired or growing and these are called mesenchymal cells. Now we already looked at the presence of macrophages in the previous picture and those of course are the immune cells. that are going to be phagocytic and they can consume debris or pathogens. Mast cells are involved in inflammation, so they're going to release the substances histamine and hep. Lymphocytes we see here, an example of one type of lymphocyte, are going to be immune cells that are going to be involved in our specific immune system. So when we're finding specific pathogen with antibodies, it's going to involve lymphocytes. And here's our mast cell over here. Microphages are another type of phagocytic blood cell. They're just smaller. And we also will find melanocytes. Now we're going to spend a lot more time on melanocytes in chapter 5 when we cover the integument. Melanocytes, as we see in illustration here, are going to contain the pigment we call melanin. Melanin is found in various types of tissue in our body and has the ability to provide different color to different areas of our body such as our skin and our hair and our eyes. This is just a picture showing different components that you would find in the connective tissue. You're probably not going to find all these in one spot, but this is illustrating all of them. Now let's start by looking at connective tissue proper. Okay, connective tissue proper can be either categorized as loose connective tissue or dense connective tissue. This is going to be based on the organization of that particular tissue of the cells and the surrounding matrix. Now with the loose connective tissue, think of this as the packing material in your body. So if you get a box from Amazon and it's filled with the bubble packs or maybe styrofoam peanuts, they don't use those very much anymore. Or maybe you buy something, a new electronic piece, and it's got that big thick styrofoam around it, making sure that it's held securely into place. This can be thought of as the different types of loose connective tissue. And we're going to look at three different types. Areolar, adipose, and reticular. We're going to look at the first two in lab. Now the other type of connective tissue proper is going to be the dense connective tissue. And this can be classified as either dense regular connective tissue or dense irregular connective tissue, where the regular and irregular is going to refer to the collagen fiber organization we see in this particular connective tissue. Now, what you'll notice in the difference between the loose and the dense is that in the dense, you're going to see a high density of these fibers, not as much ground substance between the cells. The first loose connective tissue we're going to look at is the areolar connective tissue. This is the least specialized of all of the connective tissues. We find this kind of all over the body. As you can see, the organization is very loosely organized. Now, the different types of fiber in here, we have... collagen fibers, we have elastic fibers, and you can see the nuclei of many different types of cells. Now another type of loose connective tissue is the adipose tissue, which many of you may be familiar with is our fat tissue. The cells that we find within the fat tissue are going to be referred to as the adipocytes. So each of these is an adipocyte. Remember how we looked at that slide previously? The white area is not empty. This is the inside of the fat cell that is filled with a fat vacuole full of fat, and it's pushing all the structures to the periphery. So for instance, we see the nuclei pushed off to the side. Now, We can have different types of fat in our body. The white fat is the most common type of fat that we have as adults. We're going to store our fat energy here. It's going to work as insulation to help protect organs from impact and jostling, as well as temperature changes within the body. Brown fat you're going to find in a higher percentage in young children and infants. It has a higher metabolic rate. It helps generate more heat. I'm sure this is a protective measure in order to protect growing children from the cold. cold environment that they could potentially be subjected to. Now we also have the reticular tissue as one of the loose connective tissues and we can see here reticular means network within the tissue so we see here that these fibers have formed a very mesh-like appearance and as we mentioned before this is going to be the tissue that comprises that support system we call a stroma, which is going to help support the functional tissue called the parenchyma in various organs such as the spleen and liver. Now we will not look at reticular tissue in the lab. Now let's look at the dense connective tissues. So the T. Dense regular connective tissue is going to have tightly organized collagen fibers that are almost parallel. Sometimes they are wavy. So let's go to the next picture. Here would be an illustration and supported by a histology slide of dense regular connective tissue. The pink here is going to be all your collagen fibers. Almost completely parallel, very organized, very tight. The fibroblast cells are going to have these nuclei which we see stained the dark purple. They are not as numerous as we find in other tissues. Now if we compare that to the dense irregular connective tissue, we find this in areas such as a layer of our skin. Notice how the collagen fibers, although they're tightly packed together, they're not organized in that very unique parallel fashion. They're a little bit more irregularly placed. We also see the nuclei stain the dark purple once again throughout the collagen fiber bundles. Now, if we go back here, there is also a... type of dense regular connective tissue called elastic tissue we find in certain areas of our body such as within our vertebrae elastic tissue is going to have the elastic fibers within it we see the squiggly lines okay they're going to contribute the property of elasticity to this particular connective tissue Okay, so let's look at another type of connective tissue. This is fluid connective tissue, and this is going to be including the fluid in our body we call blood. Most of us are probably familiar with that, but another fluid we have in our body is called lymph. Now, lymph is part of our lymphatic system, and it's going to function with our immune system. It's also going to have other functions such as regulating the fluid levels in different areas of our body. Now we remember that connective tissue consists of cells within a matrix. So the matrix of the fluid connective tissue is going to be a liquid component, which in blood is going to be the plasma. Now the cells, quote unquote, cells that we find in this blood, fluid connective tissue, are really called formed elements. These formed elements are going to consist of the red blood cells, also known as erythrocytes. They're going to consist of white blood cells, also known as leukocytes, and of platelets that are actually cell fragments. So we call these quote-unquote cells formed elements because they're going to be formed. The red blood cells and the platelets are not truly cells, they're just portions of cells in their mature form. Now, the matrix, or the extracellular fluid that we find in the different types of these fluids within our body, we have the plasma for blood, interstitial fluid is the fluid that we find in our tissues. And lymph is the fluid that we find in our lymphatic system. Now, just to expand a little bit on the lymph, we touched a little bit previously on the functions of the lymph. It's in the space between your cells and your tissue space called the interstitial space. The immune system is going to be involved with the lymphatic system, and the lymphatic fluid is also going to be a component of circulation with the circulatory system. So these are the comparison of your lymphatic system, we can see the lymphatic system is often depicted in green in how the vessels extend throughout the body. As compared to your cardiovascular system, the cardiovascular system is composed of your heart and the blood vessels that carry blood to your tissues and back to your heart again. We can see that there's quite a bit of similarities between the areas where they meet. flow. Now the next type of connective tissue is the supporting connective tissue. So this is going to support the structure of our body. So this is probably going to make sense that is going to include our skeleton which is going to be comprised of the tissue we call bone. Most of us are pretty familiar with that. Now we also have another type of tissue that is called cartilage. Now let's start with the cartilage. Cartilage is going to have the cells that are in the matrix that's more of a gel like. So cartilage is going to be involved in absorbing the impact of shock. We're going to find it in specific areas in our skeleton such as at the end of some long bones. at joints to help absorb shock. Bone is going to have a matrix that is calcified, so it's hard, it's rigid, and this is because we have the deposition of calcium salts and also some minerals within it. So as we mentioned previously, that each tissue varies because of differences of the constituents of the matrix. We can see this here. Think of the matrix for our fluid connective tissue compared to the connective or the matrix of the bone connective tissue. Very different. Let's take a closer look at the cartilage. Now the cartilage matrix is going to include some proteoglycans. So remember those proteins with carbohydrates attached to it contributing the characteristic viscosity. The matrix we can see is going to be what appears to be clear, almost glass-like around these structures, the cellular structures. Now the cells that are associated with cartilage are called chondrocytes. So when you see this term chondro As the semester and actually both semesters of this class continue, that is going to tell you that you are working with cartilage. So you want to hang on to that chondro. Cite tells you cells. The chondrocytes are going to be the cells that we find within these chambers. So here is a chondrocyte, here is... Chondrocyte and probably what we're seeing is the nuclei stained. Here is a chondrocyte. Now the chondrocytes are found in these chambers. If you notice, they kind of look like eyeballs. The chamber is called a lacunae. So the lacunae is going to be this white chamber around each chondrocyte. So there's a lacunae. So they look kind of like eyes staring out of you, maybe eyeballs in some clear jello. So if we're thinking about Halloween-y type things. Now notice here that this says there are no blood vessels. As mentioned previously, the cartilage is avascular, meaning that if you have an injury to cartilage, it is not going to heal. heal very quickly or very well. The cartilage is also surrounded by a layer, a membranous layer, we call the perichondrium. So peri telling you. you that it means around around and the chondro is telling you it just wants to skip on me chondro is telling you that it's the cartilage this perichondrium consists of outer and inner later layer so the outer layer is going to be more fibrous the inner is going to be more cellular so you're going to have more growth there Now, there are three different types of cartilage in our body. The first type we're going to look at is hyaline. Hyaline is the most common cartilage in our body. And we're going to find this in areas such as joints we call synovial joints, such as at our knee. We're going to see it at our trachea. How you see or feel your trachea is ridged, that's because it has hyaline cartilage around it for support. There is also... a type of cartilage we call elastic cartilage. We find this around our ears, so the top part of your ear is kind of bendy, and fibrocartilage. Fibrocartilage is quite strong. We're going to find this in various areas such as the pubic symphysis. So this illustration is showing us where we find different types of cartilage. So we see the elastic cartilage around in our ear. So your ear will bend, and return back to its original shape. Fibrocartilage we can find associated with the vertebrae. I like the example of a pubic symphysis which is going to be a piece of cartilage connecting your two pelvic bones in the anterior side. Hyaline cartilage you can find at the end of long bones at joints. We can also find hyaline cartilage and the cartilage associated with our rib cage. And this is the different appearances. We will look at the hyaline cartilage in lab and then we have the bone or the osseous tissues. So when you see osseo or osteo that's going to tell you you're looking at bone. As we know bone is very strong. So remember connective tissue. is cells surrounded by a matrix. The cells that we find in the bone tissue are called osteocytes. So osteo for bone, site for cell. Now once again, similar to the cartilage, we are going to find these osteocytes housed within chambers that we call lacunae. The lacunae are going to be these dark structures we find circling around the central portion of the bone. They look kind of like ants or a little spider with legs sticking out. So the osteocytes are going to be housed in these lacunae. Now we're not going to be able to see the osteocyte on slides and lab. It's too small. These Spider legs that extend out from each lacunae, we can see these, these are canaliculi. They are going to be the mechanism, or here's a good spot, we can see a lot of the canaliculi extending here. This is the structures that allow the osteocytes to communicate with each other. Now in the center here we see a large circle. This is our central canal. This is where we're going to find the blood vessels, the artery and vein that are going to supply blood to the bone tissue. Now as we will continue on and learn, we are going to see that bone tissue is organized in these larger functional units we call osteons. And this one's can cut off a little bit. We can see one here. They look like a tree trunk that has been cut off. So if you're looking down at a tree stump and you see the tree rings, that is similar to what we're looking at. The osteon. We see the central canal and we see the ring-like structures, these circular ring-like structures. These are lamellae and we see the lacunae are centered. on the lamellae. The periosteum, similar to the perichondrium, is going to be that membranous layer surrounding the bone tissue. So let's look here at another illustration of the bone tissue. We can see from this histology slide that functional unit of the bone that we call the osteon. It looks like a tree trunk. The central canal It's going to be in the middle, and it's going to have the blood vessels associated with it that are going to provide the nutrition to the bone. Each of these concentric rings is a lamellae, and the dark spots are going to be the lacunae that has the osteocytes housed within it. The legs extending off of these lacunae are called the canaliculi. You can see this from this illustration, the canaliculae, and you can see the little osteocyte within the lacunae on this picture. The periosteum is this layer, membranous layer, surrounding the outside of the bone. We have the outer fibrous layer, the intercellular layer, similar to what we saw with the cartilage structure.

Now these fibers are going to be composed of different types of protein. The connective tissue is going to be very broad in its spectrum for its functions and also that's going to show up. in a great variety in its structures. So connective tissue in our bodies is going to help serve as a structural component.

So it's going to be considered part of our skeletal system. It's going to be involved in transportation of moving things from one area of the body to the other. Protection of our organs and parts of our body and connecting them.

We store energy in connective tissue. It's also going to be involved in their immune system and defending our bodies against pathogens. Most connective tissue is vascularized.

Now cartilage we will find out really isn't. But the whereas the epithelial tissue is avascular, the connective tissue does have a blood supply. And there's also going to be sensory function associated with this connective tissue as well.

Let's look at that extracellular matrix. Okay, it's this substance that's going to surround the cells, and it is going to include what we refer to as that ground substance, and it has fibers within it. So the ground substance is this colorless, yet viscous. fluid that we would find surrounding the cell.

So here's our phospholipid bilayer, the intracellular environment, our extracellular environment. What we see is the extracellular matrix here is surrounding it, and it is not just devoid of any components. It's going to have very specific structures associated with it and molecules as well.

And in fact, The characteristics of the tissue is going to vary according to variations in this extracellular matrix. The particular nature and properties of the components within this matrix make each connective tissue different. We can see here the fibers and we can see glycoproteins. Now the different types of connective tissue that we're going to look at are going to be either referred to as connective tissue proper which can either be of the loose variety or dense and this is going to be based on the organization of the substances within the connective tissue now the next type of connective tissue is going to be the fluid connective tissue The fluid connective tissue is going to be when you have your cells surrounded by the matrix, but the matrix is going to be a fluid system.

And the supporting connective tissue is going to be the type of connective tissue involved in providing structure for our body, such as the bones. And what we're going to see is a change in the number of cells and we're going to see more of the matrix with the fibers. Now in the connective tissue we're going to see different types of fibers.

So the first and most common types of fibers that we are going to see are the collagen fibers. This is made of the protein we called collagen. These collagen fibers are very strong so they provide strength to the particular tissue that they are included in and to some degree some flexibility.

So the collagen fibers are going to provide strength and resistance when pressure is placed on this tissue. one direction such as compression in a vertical plane. We find collagen fibers in tissues such as our tendons and ligaments. Tensins are going to connect muscle to bone and ligaments are going to connect bone to bone. Now another type of fiber that is going to be made of the collagen protein also are the reticular fibers.

Now they're organized differently than we saw previously. The reticular fibers are going to create more of a network, almost like a mesh. And we call this the stroma. And we find this in organs such as our liver and our spleen.

And this stroma is going to provide support for the functional component of those particular organs. And the functional component we refer to as the parenchyma. Now because of the organization of these reticular fibers in this mesh-like network, it's going to be able to absorb forces coming at it from many different directions, not just one plane of direction. And we're also going to see these type of fibers present in certain organs that have the surrounding tissue called the sheath around it that's going to be protective. Now another type of fiber that we will find is called elastic fibers.

This is going to include the protein we called elastin. And as the name would imply, this type of fiber allows the property of being able to stretch and then recoil back into its original shape. This is just an illustration of a histology slide.

showing these different types of fiber and we're going to look at these in the lab. These rather translucent fibers here, these are the collagen fibers. These have stained very nicely.

It's almost like you can see through them. Now the darker thin lines that look like a hair may have fallen across your slide, these are the elastic fibers. made of the protein elastin.

Now what we see these dark spots, these are going to be representing cells. Here we see a fibroblast. The fibroblast we'll look at are the cells that actually create the proteins that generate the fibers and a macrophage. And those are an immune type cell that are going to help clean up debris.

Now The cells that are present in the connective tissue are a variety. So we'll just touch on each of these. So remember, the connective tissue is going to be cells surrounded by a matrix.

So we see the first type of cell, the most common type of cell, are these fibroblasts. So here's a picture of fibroblasts. These are going to secrete the proteins that are used to make the fibers. Now the second most abundant type of cell that we find are fibrocytes.

Now the fibrocytes are going to be involved in maintaining this connective tissue. We may see a certain type of connective tissue have cells called adipocytes. These are really just fat cells. This is a picture of adipocytes over here.

We can see each of these is a cell. And what we see is the boundary of the cell membrane in pink. And the white part in the center may appear empty or clear, but it is actually a vacuole area that is filled with fat. So it's a fat droplet within this fat vacuole.

Now we may also see stem cells which can regenerate and replace tissue that is being repaired or growing and these are called mesenchymal cells. Now we already looked at the presence of macrophages in the previous picture and those of course are the immune cells. that are going to be phagocytic and they can consume debris or pathogens.

Mast cells are involved in inflammation, so they're going to release the substances histamine and hep. Lymphocytes we see here, an example of one type of lymphocyte, are going to be immune cells that are going to be involved in our specific immune system. So when we're finding specific pathogen with antibodies, it's going to involve lymphocytes. And here's our mast cell over here. Microphages are another type of phagocytic blood cell.

They're just smaller. And we also will find melanocytes. Now we're going to spend a lot more time on melanocytes in chapter 5 when we cover the integument. Melanocytes, as we see in illustration here, are going to contain the pigment we call melanin.

Melanin is found in various types of tissue in our body and has the ability to provide different color to different areas of our body such as our skin and our hair and our eyes. This is just a picture showing different components that you would find in the connective tissue. You're probably not going to find all these in one spot, but this is illustrating all of them. Now let's start by looking at connective tissue proper. Okay, connective tissue proper can be either categorized as loose connective tissue or dense connective tissue.

This is going to be based on the organization of that particular tissue of the cells and the surrounding matrix. Now with the loose connective tissue, think of this as the packing material in your body. So if you get a box from Amazon and it's filled with the bubble packs or maybe styrofoam peanuts, they don't use those very much anymore.

Or maybe you buy something, a new electronic piece, and it's got that big thick styrofoam around it, making sure that it's held securely into place. This can be thought of as the different types of loose connective tissue. And we're going to look at three different types. Areolar, adipose, and reticular. We're going to look at the first two in lab.

Now the other type of connective tissue proper is going to be the dense connective tissue. And this can be classified as either dense regular connective tissue or dense irregular connective tissue, where the regular and irregular is going to refer to the collagen fiber organization we see in this particular connective tissue. Now, what you'll notice in the difference between the loose and the dense is that in the dense, you're going to see a high density of these fibers, not as much ground substance between the cells.

The first loose connective tissue we're going to look at is the areolar connective tissue. This is the least specialized of all of the connective tissues. We find this kind of all over the body.

As you can see, the organization is very loosely organized. Now, the different types of fiber in here, we have... collagen fibers, we have elastic fibers, and you can see the nuclei of many different types of cells.

Now another type of loose connective tissue is the adipose tissue, which many of you may be familiar with is our fat tissue. The cells that we find within the fat tissue are going to be referred to as the adipocytes. So each of these is an adipocyte.

Remember how we looked at that slide previously? The white area is not empty. This is the inside of the fat cell that is filled with a fat vacuole full of fat, and it's pushing all the structures to the periphery. So for instance, we see the nuclei pushed off to the side. Now, We can have different types of fat in our body.

The white fat is the most common type of fat that we have as adults. We're going to store our fat energy here. It's going to work as insulation to help protect organs from impact and jostling, as well as temperature changes within the body. Brown fat you're going to find in a higher percentage in young children and infants.

It has a higher metabolic rate. It helps generate more heat. I'm sure this is a protective measure in order to protect growing children from the cold.

cold environment that they could potentially be subjected to. Now we also have the reticular tissue as one of the loose connective tissues and we can see here reticular means network within the tissue so we see here that these fibers have formed a very mesh-like appearance and as we mentioned before this is going to be the tissue that comprises that support system we call a stroma, which is going to help support the functional tissue called the parenchyma in various organs such as the spleen and liver. Now we will not look at reticular tissue in the lab.

Now let's look at the dense connective tissues. So the T. Dense regular connective tissue is going to have tightly organized collagen fibers that are almost parallel. Sometimes they are wavy.

So let's go to the next picture. Here would be an illustration and supported by a histology slide of dense regular connective tissue. The pink here is going to be all your collagen fibers.

Almost completely parallel, very organized, very tight. The fibroblast cells are going to have these nuclei which we see stained the dark purple. They are not as numerous as we find in other tissues.

Now if we compare that to the dense irregular connective tissue, we find this in areas such as a layer of our skin. Notice how the collagen fibers, although they're tightly packed together, they're not organized in that very unique parallel fashion. They're a little bit more irregularly placed.

We also see the nuclei stain the dark purple once again throughout the collagen fiber bundles. Now, if we go back here, there is also a... type of dense regular connective tissue called elastic tissue we find in certain areas of our body such as within our vertebrae elastic tissue is going to have the elastic fibers within it we see the squiggly lines okay they're going to contribute the property of elasticity to this particular connective tissue Okay, so let's look at another type of connective tissue. This is fluid connective tissue, and this is going to be including the fluid in our body we call blood.

Most of us are probably familiar with that, but another fluid we have in our body is called lymph. Now, lymph is part of our lymphatic system, and it's going to function with our immune system. It's also going to have other functions such as regulating the fluid levels in different areas of our body. Now we remember that connective tissue consists of cells within a matrix. So the matrix of the fluid connective tissue is going to be a liquid component, which in blood is going to be the plasma.

Now the cells, quote unquote, cells that we find in this blood, fluid connective tissue, are really called formed elements. These formed elements are going to consist of the red blood cells, also known as erythrocytes. They're going to consist of white blood cells, also known as leukocytes, and of platelets that are actually cell fragments. So we call these quote-unquote cells formed elements because they're going to be formed.

The red blood cells and the platelets are not truly cells, they're just portions of cells in their mature form. Now, the matrix, or the extracellular fluid that we find in the different types of these fluids within our body, we have the plasma for blood, interstitial fluid is the fluid that we find in our tissues. And lymph is the fluid that we find in our lymphatic system.

Now, just to expand a little bit on the lymph, we touched a little bit previously on the functions of the lymph. It's in the space between your cells and your tissue space called the interstitial space. The immune system is going to be involved with the lymphatic system, and the lymphatic fluid is also going to be a component of circulation with the circulatory system.

So these are the comparison of your lymphatic system, we can see the lymphatic system is often depicted in green in how the vessels extend throughout the body. As compared to your cardiovascular system, the cardiovascular system is composed of your heart and the blood vessels that carry blood to your tissues and back to your heart again. We can see that there's quite a bit of similarities between the areas where they meet.

flow. Now the next type of connective tissue is the supporting connective tissue. So this is going to support the structure of our body. So this is probably going to make sense that is going to include our skeleton which is going to be comprised of the tissue we call bone. Most of us are pretty familiar with that.

Now we also have another type of tissue that is called cartilage. Now let's start with the cartilage. Cartilage is going to have the cells that are in the matrix that's more of a gel like. So cartilage is going to be involved in absorbing the impact of shock. We're going to find it in specific areas in our skeleton such as at the end of some long bones.

at joints to help absorb shock. Bone is going to have a matrix that is calcified, so it's hard, it's rigid, and this is because we have the deposition of calcium salts and also some minerals within it. So as we mentioned previously, that each tissue varies because of differences of the constituents of the matrix.

We can see this here. Think of the matrix for our fluid connective tissue compared to the connective or the matrix of the bone connective tissue. Very different. Let's take a closer look at the cartilage. Now the cartilage matrix is going to include some proteoglycans.

So remember those proteins with carbohydrates attached to it contributing the characteristic viscosity. The matrix we can see is going to be what appears to be clear, almost glass-like around these structures, the cellular structures. Now the cells that are associated with cartilage are called chondrocytes. So when you see this term chondro As the semester and actually both semesters of this class continue, that is going to tell you that you are working with cartilage.

So you want to hang on to that chondro. Cite tells you cells. The chondrocytes are going to be the cells that we find within these chambers.

So here is a chondrocyte, here is... Chondrocyte and probably what we're seeing is the nuclei stained. Here is a chondrocyte.

Now the chondrocytes are found in these chambers. If you notice, they kind of look like eyeballs. The chamber is called a lacunae.

So the lacunae is going to be this white chamber around each chondrocyte. So there's a lacunae. So they look kind of like eyes staring out of you, maybe eyeballs in some clear jello. So if we're thinking about Halloween-y type things. Now notice here that this says there are no blood vessels.

As mentioned previously, the cartilage is avascular, meaning that if you have an injury to cartilage, it is not going to heal. heal very quickly or very well. The cartilage is also surrounded by a layer, a membranous layer, we call the perichondrium.

So peri telling you. you that it means around around and the chondro is telling you it just wants to skip on me chondro is telling you that it's the cartilage this perichondrium consists of outer and inner later layer so the outer layer is going to be more fibrous the inner is going to be more cellular so you're going to have more growth there Now, there are three different types of cartilage in our body. The first type we're going to look at is hyaline.

Hyaline is the most common cartilage in our body. And we're going to find this in areas such as joints we call synovial joints, such as at our knee. We're going to see it at our trachea. How you see or feel your trachea is ridged, that's because it has hyaline cartilage around it for support. There is also...

a type of cartilage we call elastic cartilage. We find this around our ears, so the top part of your ear is kind of bendy, and fibrocartilage. Fibrocartilage is quite strong. We're going to find this in various areas such as the pubic symphysis. So this illustration is showing us where we find different types of cartilage.

So we see the elastic cartilage around in our ear. So your ear will bend, and return back to its original shape. Fibrocartilage we can find associated with the vertebrae.

I like the example of a pubic symphysis which is going to be a piece of cartilage connecting your two pelvic bones in the anterior side. Hyaline cartilage you can find at the end of long bones at joints. We can also find hyaline cartilage and the cartilage associated with our rib cage.

And this is the different appearances. We will look at the hyaline cartilage in lab and then we have the bone or the osseous tissues. So when you see osseo or osteo that's going to tell you you're looking at bone. As we know bone is very strong. So remember connective tissue.

is cells surrounded by a matrix. The cells that we find in the bone tissue are called osteocytes. So osteo for bone, site for cell. Now once again, similar to the cartilage, we are going to find these osteocytes housed within chambers that we call lacunae. The lacunae are going to be these dark structures we find circling around the central portion of the bone.

They look kind of like ants or a little spider with legs sticking out. So the osteocytes are going to be housed in these lacunae. Now we're not going to be able to see the osteocyte on slides and lab. It's too small. These Spider legs that extend out from each lacunae, we can see these, these are canaliculi.

They are going to be the mechanism, or here's a good spot, we can see a lot of the canaliculi extending here. This is the structures that allow the osteocytes to communicate with each other. Now in the center here we see a large circle.

This is our central canal. This is where we're going to find the blood vessels, the artery and vein that are going to supply blood to the bone tissue. Now as we will continue on and learn, we are going to see that bone tissue is organized in these larger functional units we call osteons. And this one's can cut off a little bit.

We can see one here. They look like a tree trunk that has been cut off. So if you're looking down at a tree stump and you see the tree rings, that is similar to what we're looking at. The osteon.

We see the central canal and we see the ring-like structures, these circular ring-like structures. These are lamellae and we see the lacunae are centered. on the lamellae. The periosteum, similar to the perichondrium, is going to be that membranous layer surrounding the bone tissue.

So let's look here at another illustration of the bone tissue. We can see from this histology slide that functional unit of the bone that we call the osteon. It looks like a tree trunk.

The central canal It's going to be in the middle, and it's going to have the blood vessels associated with it that are going to provide the nutrition to the bone. Each of these concentric rings is a lamellae, and the dark spots are going to be the lacunae that has the osteocytes housed within it. The legs extending off of these lacunae are called the canaliculi. You can see this from this illustration, the canaliculae, and you can see the little osteocyte within the lacunae on this picture.

The periosteum is this layer, membranous layer, surrounding the outside of the bone. We have the outer fibrous layer, the intercellular layer, similar to what we saw with the cartilage structure.

Transcript for:Understanding Connective Tissue Functions and Types

Transcript for:
Understanding Connective Tissue Functions and Types