Introduction to the Integumentary System - Online Tutor, Practice Problems & Exam Prep

Introduction to the Integumentary System

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's 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, the skin 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 all 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 and a half kilograms, which is pretty heavy.

But the integumentary system includes more than just the skin. It's composed of these 3 different parts that you can see numbered down below: 1, 2, and 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. This bracket here indicates that the cutaneous membrane, or the skin, includes both the epidermis and the dermis.

However, the cutaneous membrane, or the skin, does not include accessory structures. The integumentary system includes both the cutaneous membrane, or the skin, which includes the epidermis and dermis, as well as the accessory structures. The epidermis is the outermost layer of the skin. From our previous lesson videos on tissues, the epidermis or the outermost layers of our skin is made up of epithelial tissue, which covers the entire external surface of the body. More specifically, the epidermis is made of stratified squamous epithelial tissue, or many layers of flat or squished cells.

The root "epi," found in the word epidermis, means above, so the epidermis lies above as the outermost layer of the skin, and it comes into direct contact with the external environment. It lies above the dermis, of course, which is a layer of mostly connective tissue that lies under the epidermis and makes up most of the skin or the cutaneous membrane.

As we move forward in our course, we'll be able to talk a lot more about the epidermis, the dermis, and accessory structures as well. It's also important to note that beneath the cutaneous membrane, or beneath the skin, lies another layer referred to as the hypodermis, also known 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. In some contexts, the integumentary system will include the hypodermis or the 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. You'll 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. The dermis makes up the vast majority of the skin. The epidermis and dermis collectively make up the cutaneous membrane, or the skin. Lying beneath the cutaneous membrane or the skin is the subcutaneous layer or the hypodermis, which is this layer here in yellow.

Throughout the integumentary system, you can also find a bunch of accessory structures, including hairs that you can see protruding through. You can see some oil glands and some sweat glands as well. We'll be able to talk a lot more about the epidermis, dermis, hypodermis, and accessory structures as we move forward in our course. But for now, this concludes our brief introduction to the integumentary system, and I'll see you all in our next video.

Integumentary System Functions

This video we're going to talk about integumentary system functions and it turns out the integumentary system has a lot of different functions. Here in this video, we're only going to talk broadly about some of its most important functions. The integumentary system has several different functions including the following broad functions that we have numbered down below. The first broad function that we have here in our lesson is that it provides protection. This is probably its most notable function. Recall that the integumentary system includes our skin.

We know that our skin covers the entire external surface of our body. It separates the outside world, or the outside environment, from the inside of our bodies. It can protect us against mechanical stresses such as friction, 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. 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. 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. This includes 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. Vitamin D is a critical nutrient that's important for bones.

Also, the integumentary system allows for excretions from the body releasing wastes via sweating. 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. This is because the integumentary system contains nervous tissue that 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.

For example, notice that the left side of this person's face here looks like a very serious person. We can tell that just by looking at the person's skin, which is part of the integumentary system. Notice that on the right side, you can tell that this person is actually a lot happier. You can detect the emotions just by looking at the facial expressions. 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.

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?

• A. Epidermis and accessory structures.
• B. Dermis and accessory structures.
• C. Epidermis and dermis.
• D. Epidermis, dermis, and hypodermis.

Map of the Lesson on Integumentary System

In this video, we're going to introduce our map of the lesson on the integumentary system, which is down below right here. 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. You can use it to make predictions about what topics we're going to cover next and to help you figure out where you are within the lesson and how much is left within the lesson. We will follow this map from top to bottom, but also from left to right. Notice at the very top we have the introduction to the integumentary system, where we are currently.

This will include talking about the functions of the integumentary system. Notice we have the cutaneous membrane or the skin, which we know from our previous lesson videos includes the epidermis and the dermis. We will then talk about epidermal cells including keratinocytes, melanocytes, dendritic cells, and tactile epithelial cells. We will discuss the epidermal layers or the layers of the epidermis including the stratum corneum, lucidum, granulosum, spinosum, and basale. After discussing the epidermis, we will talk more about the dermis, including its 2 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 discuss the cutaneous membrane or the skin, we'll focus on the subcutaneous layer or the hypodermis. We will then move on to talk about skin pigmentation or skin color, including factors such as melanin, keratin, and hemoglobin, and we'll also discuss the evolution of skin color. After skin pigmentation, we will talk about accessory structures including hair, such as the different types, color, and growth cycle. We will discuss nails, sweat glands including eccrine and apocrine sweat glands, and ceruminous and mammary glands. We will also talk about sebaceous glands or oil glands.

After discussing those accessory structures, we will 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. Finally, we will discuss wrinkles and aging. 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.