In this video, we're going to talk about the second type of dense connective tissue in our lesson, which is dense irregular connective tissue, which is pretty much made of the same structural components as dense regular connective tissue. And the biggest difference is that the protein fibers in the extracellular matrix are going to form an irregular or a random protein fiber arrangement. And so we can say that dense irregular connective tissue is going to have really densely packed protein fibers in the extracellular matrix that form an irregular or a random protein fiber arrangement instead of being in a parallel arrangement like dense regular connective tissue. Now, in terms of the composition, again, it's mostly going to be collagen protein fibers that make up the fibers in the extracellular matrix. However, there can be a smaller amount of elastic protein fibers as well.
But, again, it's mostly collagen fibers. And so recall that the collagen fibers are made up of smaller collagen proteins, which are non-elastic proteins that are designed for strength. And so recall that these collagen fibers are going to be relatively long, thick, unbranched, and straight protein fibers, which give them a lot of strength. However, the collagen fibers are not completely stiff, and they have a little bit of a wave to them, which gives them a little bit of flexibility. But, again, once those fibers have been straightened out, that is when their strength truly shows because they are going to, again, resist pulling forces and tension.
Now in terms of the function, because the collagen fibers are randomly arranged in all kinds of directions, this means that dense irregular connective tissue is going to be specialized for strength, but actually in multiple different directions, unlike being specialized for strength in just one particular direction along the axis of the parallel fibers in dense regular connective tissue. And so because these fibers are, again, randomly arranged in dense irregular connective tissue, that means that all of the fibers are not going to be working together in the same direction. And so that means that it's not going to be quite as strong as dense regular connective tissue, which has parallel arranged collagen fibers that are all working in the same direction. And so in terms of its functions, it is going to provide structural strength and protection, again, because it can resist forces in multiple directions. And so we can expect to find it in locations of the body where they need to be able to resist forces in multiple directions.
For example, dense irregular connective tissue is actually going to be found beneath the areolar loose connective tissue in our skin. And so, dense irregular connective tissue actually makes up the larger portion of the dermis, which is part of our skin. And there, it's going to help prevent the tearing of the skin, again, because it can resist forces in multiple directions. Dense irregular connective tissue can also be found wrapping joints, organs, such as the heart, for example. It makes up the pericardium around the heart or part of it, and it can be found wrapping around bones as well.
Notice here we have an image showing a diagram of the skin. Recall from our previous lesson videos that the outermost layers of the skin are made of an epithelial tissue known as stratified squamous epithelia, which is this outer layer that you can see highlighted right there. And then beneath that, this light blue layer that's very thin represents the areolar connective tissue, a type of loose connective tissue that we talked about in our previous lesson videos. And then beneath the areolar connective tissue, as we indicated over here in the text, is going to be where the dense irregular connective tissue can be found in the skin. And so that's going to be represented by this darker, larger blue region that you can see indicated here.
The dense irregular connective tissue makes up the vast majority of the layer of the skin known as the dermis. And there, it's going to provide, again, resistance to forces in multiple directions, which are really important for the skin to have. In fact, an interesting note is that the product leather is made from the dermis of animal skins. And in the dermis, again, it's made of mostly dense irregular connective tissue. And the ability for dense irregular connective tissue to resist forces in multiple directions is what gives the product leather its durability.
Now, beneath the dense irregular connective tissue is a layer known as the subcutaneous layer, which is mostly made of adipose tissue. Later in our course, in a different chapter when we're talking about the integumentary system, we're going to talk a lot more details about the skin and so we'll revisit all of this again. Dense irregular connective tissue, again, can also be found wrapping joints. Notice here, we can see the dense irregular connective tissue wrapping the joints, again, allowing it to resist forces in multiple directions, which are important for joints. Notice here, we have a micrograph of the dense irregular connective tissue.
What you'll notice is that the fibers are going to be very thick fibers. And the darker spots that you can see in a purplish or bluish color, those are the fibroblasts. And so notice that, again, the fibers are going to be made of mostly collagen fibers. And you can see that they have some regions here that are kind of longitudinal, you know, collagen fibers. But then there are other regions that you can clearly see are more dense and irregularly shaped, collagen fibers.
These irregularly shaped collagen fibers that have this random arrangement allow this entire dense irregular connective tissue to resist forces again in multiple different directions. And so this here concludes our lesson on dense irregular connective tissue. Moving forward, we'll be able to apply these concepts and talk about the last type of dense connective tissue. I'll see you all in our next video.