Introduction to the Integumentary System - Video Tutorials & Practice Problems
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Introduction to the Integumentary System
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6m
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In this video, we're going to begin our introduction to the integumentary system. And so recall from our previous lesson videos, way back in chapter one, that the integumentary system is one of many different organ systems found in the human body. And it's actually made up of the skin, which we know 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. And so the integumentary system actually contains all four of the primary types of tissues that we covered in our previous lesson videos including epithelial connective muscle and nervous tissues. And the skin actually plays a huge role in the integumentary system. In fact, the skin is actually the largest organ in the human body in terms of both its surface area and its weight. And so if we were to flatten it and lay it all out, the skin could take up an area of about 22 square feet or two square meters, which is a pretty big amount of space. And in terms of its weight, the skin alone can be over £10 in weight or over 4.5 kg, which is pretty heavy. But again, the integumentary system includes more than just the skin. And it's actually composed of these three different parts that you can see numbered down below 12 and three. And so the first part of the integumentary system is the epidermis. The second part is the dermis. And the third part are the accessory structures. And so it's really important to note that together the epidermis and the dermis, technically make up the skin, which is also referred to as the cutaneous membrane. And so notice this bracket here is indicating that the cutaneous membrane or the skin actually 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 as well. Now, the epidermis is actually the outermost layer of the skin. And recall from our previous lesson, videos on tissues that the epidermis or the outermost layers of our skin is actually made up of epithelial tissue, which we know is tissue that covers things. And we know that the skin covers the entire external surface of the body. And recall that more specifically the epidermis or the outermost layer of the skin is actually made of stratified squamous epithelial tissue or many layers of these flat or squished cells. Now, it's helpful to note that the root epi, which is found in the word epidermis is a root that means above. And so the epidermis does lie above as the outermost layer of the skin. And so it comes into direct contact with the external environment. And it does, the epidermis actually does lie above the dermis, of course, and the dermis is a layer of mostly connective tissue that lies under the epidermis. And the dermis actually makes up most of the skin or most of the cutaneous membrane. And uh we'll be able to see that down below in our diagram. Now, the accessory structures includes hair, nails, sweat glands and sebaceous glands as well. And as we move forward in our course, we'll be able to talk a lot more details about the epidermis, the dermis and accessory structures as well. Now, it's also important to note that beneath the cutaneous membrane or beneath the skin lies yet another layer referred to as the hypodermis. And the hypodermis is also referred to as the subcutaneous layer. And so the root hypo and the root sub are roots that both mean low or below. And so you can think the hypodermis lies below the dermis and the subcutaneous layer lies below the cutaneous membrane or the skin. Now, it's also worthy of noting that in some contexts, the integumentary system will actually include the hypodermis or the subcutaneous layer in addition to the epidermis, dermis and accessory structures. But in other context, it doesn't include the hypodermic or subcutaneous layer. And so in our lesson, we're going to say that the integumentary system includes only the epidermis, dermis and accessory structures. But the hypodermic or subcutaneous layer is a separate layer that lies underneath. And so let's take a look at this diagram down below where we can start to piece things together. And this is a diagram of the integumentary system. And what you'll notice is that the outermost layer of the skin here is actually the epidermis. And notice that beneath the epidermis, we have this big pink area and this big pink area that you see here is the dermis and notice that the dermis actually makes up the vast majority of the skin and the epidermis is actually a small, relatively small layer in comparison to the dermis. And again, the epidermis and dermis collectively make up the cutaneous membrane or the skin. And so you can see that all of this here would be the cutaneous membrane or the skin. And notice that lying beneath the cutaneous membrane or the skin is the subcutaneous layer or the hypodermis, which is this layer here in yellow. Now notice that throughout this uh 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. And uh we'll be able to talk a lot more about again, uh the epidermis, dermis, and hypodermis and accessory structures as we move forward in our course. But for now, this year concludes our brief introduction to the integumentary system and I'll see you all in our next video.
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Integumentary System Functions
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3m
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In 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 body. 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 one, 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, uh 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 um 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 uh 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.
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Problem
Problem
What does the cutaneous membrane (skin) consist of?
A
Epidermis and accessory structures.
B
Dermis and accessory structures.
C
Epidermis and dermis.
D
Epidermis, dermis, and hypodermis.
4
concept
Map of the Lesson on Integumentary System
Video duration:
2m
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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 Carroo sites, 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, granulosa, spinosa and Bali. And then after we talk about the epidermis, we'll talk more about the dermis, including its two layers, uh 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 in 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, carrot 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 the different types, color and growth cycle. Then we'll talk about nails, sweat glands, including ecri and apple 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 ABC D 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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