In this video, we're going to begin our introduction to the integumentary system. Recall from our previous lesson videos way back in chapter 1 that the integumentary system is one of many different organ systems found in the human body. It is actually made up of the skin, which covers the entire external surface of the body, as well as hair, nails, glands such as sweat glands and oil glands, and sensory receptors which allow for sensations such as touch, for example. The integumentary system contains all 4 of the primary types of tissues that we covered in our previous lesson videos, including epithelial, connective, muscle, and nervous tissues. The skin plays a huge role in the integumentary system. In fact, it is the largest organ in the human body in terms of both its surface area and its weight. If we were to flatten it and lay it out, the skin could cover an area of about 22 square feet or 2 square meters, which is a pretty big amount of space. In terms of its weight, the skin alone can weigh over 10 pounds or over 4.5 kilograms, which is pretty heavy. But again, the integumentary system includes more than just the skin. It is composed of these 3 different parts that you can see numbered below: 1,2,3. The first part of the integumentary system is the epidermis, the second part is the dermis, and the third part are the accessory structures. It's important to note that together the epidermis and the dermis technically make up the skin, which is also referred to as the cutaneous membrane. Notice this bracket here is indicating that the cutaneous membrane or the skin includes both the epidermis and the dermis. But technically the cutaneous membrane or the skin does not include accessory structures. Whereas, once again, the integumentary system includes both the cutaneous membrane or the skin, which includes the epidermis and dermis, as well as the accessory structures. Now, the epidermis is the outermost layer of the skin. Recall from our previous lesson videos on tissues that the epidermis, or the outer layers of our skin, is made up of epithelial tissue, which covers things, and we know that the skin covers the entire external surface of the body. More specifically, the epidermis or the outermost layer of the skin is made of stratified squamous epithelial tissue or many layers of these flat or squished cells. It's helpful to note that the root "epi," which is found in the word epidermis, means above. So, the epidermis does lie above as the outermost layer of the skin, and it comes into direct contact with the external environment. The epidermis does lie above the dermis, of course. The dermis is a layer of mostly connective tissue that lies under the epidermis. The dermis makes up most of the skin or the cutaneous membrane, and we'll be able to see that down below in our diagram. The accessory structures include hair, nails, sweat glands, and sebaceous glands as well. As we move forward in our course, we'll be able to talk a lot more about the epidermis, the dermis, and accessory structures. It's also important to note that beneath the cutaneous membrane, or beneath the skin, lies yet another layer referred to as the hypodermis. The hypodermis is also referred to as the subcutaneous layer. The roots "hypo" and "sub" both mean low or below. So, the hypodermis lies below the dermis, and the subcutaneous layer lies below the cutaneous membrane or the skin. Worthy of noting that in some contexts, the integumentary system will include the hypodermis or subcutaneous layer, in addition to the epidermis, dermis, and accessory structures. But in other contexts, it doesn't include the hypodermis or subcutaneous layer. In our lesson, we're going to say that the integumentary system includes only the epidermis, dermis, and accessory structures, but the hypodermis or subcutaneous layer is a separate layer that lies underneath. Let's take a look at this diagram down below where we can start to piece things together. This is a diagram of the integumentary system. Notice that the outermost layer of the skin here is the epidermis. Beneath the epidermis, we have this big pink area which is the dermis. Notice that the dermis makes up the vast majority of the skin. The epidermis is a relatively small layer in comparison to the dermis. Again, the epidermis and dermis collectively make up the cutaneous membrane or the skin. You can see that all of this here would be the cutaneous membrane or the skin. Notice that lying beneath the cutaneous membrane or the skin is the subcutaneous layer or the hypodermis, which is this layer here in yellow. Throughout this integumentary system, you can also find a bunch of accessory structures, including these hairs that you can see protruding through, and you can see some oil glands and some sweat glands as well. We'll be able to talk a lot more about, again, the epidermis, dermis, and hypodermis, and accessory structures as we move forward in our course. But for now, this here concludes our brief introduction to the integumentary system, and I'll see you all in our next video.
Introduction to the Integumentary System - Video Tutorials & Practice Problems
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Introduction to the Integumentary System
Video transcript
Integumentary System Functions
Video transcript
This video we're going to talk about integumentary system functions. And so it turns out the integumentary system has a lot of different functions and so here in this video we're only going to talk broadly about some of its most important functions. And so again the integumentary system has several different functions including the following broad functions that we have numbered down below. And so the first broad function that we have here in our lesson is that it provides protection. And so this is probably its most notable function. Recall that the integumentary system includes our skin and we know that our skin covers the entire external surface of our body. So it separates the outside world or the outside environment from the inside of our bodies. And it can protect us against mechanical stresses such as friction for example, and it can serve as a barrier to many different substances including chemicals, UV light, or ultraviolet light from the sun protecting us from the sun. And it can serve as a barrier to microbes preventing microbes, bacteria, and viruses from entering into our body and causing us disease.
Now, the second main function that we have here in our lesson is that it helps to maintain homeostasis. And so recall from way back in our previous lesson videos back in chapter 1 that homeostasis is just the process of maintaining internal stable conditions despite the fact that the outside conditions could be changing drastically. And so this is going to include regulating body temperature, making sure that our internal body temperature stays stable despite the fact that the outside temperatures can be changing drastically in the environment. Also, the integumentary system plays an important role in the early steps of vitamin D synthesis. And vitamin D is a critical nutrient that's important for bones, for example. And also, the integumentary system allows for excretions from the body releasing wastes via sweating for example.
Now, the third main function that we have here in our lesson is that the integumentary system allows for sensations. Such as for example, touch and detecting temperatures and also feeling pain for example. And so, this is because the integumentary system is going to contain nervous tissue and that nervous tissue can allow for these sensations.
Now, the fourth and final function that we have here in our lesson is that the integumentary system allows for expressive nonverbal communication and emotions as well. And so for example notice that the left side of this person's face here looks like a very serious person and we can tell that just by the looking at the person's skin, which is part of the integumentary system. And notice that on the right side, you can tell that this person is actually a lot happier. And so, you can detect the emotions just by looking at the facial expressions. And so beneath the skin are skeletal muscles that allow for facial expressions and, can bend and have that skin be flexible, and that can allow for again, nonverbal communication and emotions. And so this here concludes our brief lesson on integumentary system functions, and as we move forward in our course we'll be able to learn more and apply these concepts in practice. So I'll see you all in our next video.
What does the cutaneous membrane (skin) consist of?
Epidermis and accessory structures.
Dermis and accessory structures.
Epidermis and dermis.
Epidermis, dermis, and hypodermis.
Map of the Lesson on Integumentary System
Video transcript
In this video, we're going to introduce our map of the lesson on the integumentary system, which is down below right here. And so because this is a map of our lesson, it is essentially a table of contents that you can continuously use to help guide you through our lessons on the integumentary system. And so you can use it to make predictions about what topics we're going to cover next and you can use it to help you figure out where you are within the lesson and how much is left within the lesson. And so the way that we're going to follow this map is from top to bottom, but also from left to right. And so notice at the very top we have the introduction to the integumentary system which is where we are currently and this is going to include talking about the functions of the integumentary system.
And then notice we have the cutaneous membrane or the skin, which we know from our previous lesson videos includes the epidermis and the dermis. Then we'll talk about epidermal cells including keratinocytes, melanocytes, dendritic cells, and tactile epithelial cells. And then we'll talk about epidermal layers or the layers of the epidermis, including the stratum corneum, lucidum, granulosum, spinosum, and basale. And then after we talk about the epidermis, we'll talk more about the dermis, including its two layers, the papillary layer, and talk about friction ridges, as well as the reticular layer of the dermis, and talk about cleavage lines. Once we talk about the cutaneous membrane or the skin then we'll focus on the subcutaneous layer or the hypodermis.
After that, we'll move on to talk about skin pigmentation or skin color, including factors such as melanin, keratin, and hemoglobin, and we'll also talk about the evolution of skin color. After skin pigmentation, we'll talk about accessory structures, including hair such as the different types, color, and growth cycle. Then we'll talk about nails, sweat glands including eccrine and apocrine sweat glands, and ceruminous and mammary glands, then we'll talk about sebaceous glands or oil glands. After talking about those accessory structures then we'll move on to talk about skin pathology including burns and the rule of nines, cancer including basal cell carcinoma, squamous cell carcinoma, and melanoma, and the ABCD method as well.
And then we'll finally talk about wrinkles and aging. And so really that is the flow of our lesson here on the integumentary system. And again, hopefully, you can see that this is a map and can be helpful for you to reference as we move forward in our course. So that concludes this video and I'll see you all in our next one.
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