Integument 1 Intro and skin cells

Summary

In "Integument 1 Intro and Skin Cells," Lynnea McFadden takes us on an intriguing journey under our own skin to explore this vital organ. She explains the protective and sensory functions of skin and its role in vitamin D synthesis and temperature regulation. McFadden delves into the layer structure of the skin and describes various skin cells such as stem cells, keratinocytes, melanocytes, tactile cells, and dendritic cells, explaining their functions and importance in maintaining skin health.

Highlights

• Your skin, or integument, is a familiar organ that acts as a barrier protecting your body from harm. 🛡️
• Skin is crucial for vitamin D synthesis, which is essential for healthy bone development and maintenance. 🌞
• Various skin layers and cells work together to protect, sense, and interact with the environment, illustrating the dynamic role of the skin. 🧬

Key Takeaways

• Our skin is more than just a covering; it acts as a protective shield against trauma and infection, helps regulate body temperature, and even assists in vitamin D synthesis! 🛡️
• Skin color is dictated by the production of melanin by melanocytes, with evolutionary adaptations influencing the amount of melanin based on geographical and environmental needs. 🌞
• Cells like keratinocytes, tactile cells, and dendritic cells all play unique roles, from forming protective barriers to providing sensory feedback and immune protection. 🧬

Overview

Our skin might be one of the most familiar sights to us, but there's more to it than just what meets the eye. As Lynnea McFadden shares, it's an incredible organ that offers protection against impacts and infections. It plays a role in vitamin D synthesis, which is crucial for both growing and maintaining strong bones, and serves as our first line of defense between our internal systems and the external environment.

The skin comprises three primary layers: the epidermis, dermis, and hypodermis, each housing different types of cells. McFadden introduces us to stem cells that work like a factory, producing various cells and keratinocytes, which form the bulk of what we see on our skin. Meanwhile, melanocytes, tucked away at the base, determine our skin color while doubling as a natural sunblock.

Beyond its structural beauty, our skin also excels in sensory duties. With the help of tactile cells like Merkel cells, we can perceive even the slightest touch, and dendritic cells vigilantly patrol for pathogens. This multi-functional organ is a testament to the human body's intricate design and evolutionary marvels.

Chapters

• 00:00 - 00:30: Introduction: The Skin as an Organ This chapter introduces the skin as an organ, noting its familiarity due to constant visibility. It highlights that skin, known as the integument, is an organ you can recognize as well as the skin of others that you perceive daily. The chapter underlines the personal and social awareness of the skin as an integral part of human anatomy.
• 00:30 - 01:00: Functions of the Skin The chapter titled 'Functions of the Skin' discusses the critical roles that the skin plays in the human body. Primarily, the skin functions as a protective barrier. It offers resistance to trauma and infection, ensuring that minor bumps or rough contacts do not harm our muscles or internal structures.
• 01:00 - 01:30: Protection Against Trauma and Infection This chapter discusses the vital role of the skin in protecting the body against trauma and infection. It explains how the skin acts as a barrier to prevent bacterial growth and safeguard internal organs. The text emphasizes the skin's ability to resist infection, highlighting its importance in overall health and hygiene. Simple practices like washing hands are effective due to this protective feature of the skin.
• 01:30 - 02:30: Vitamin D Synthesis and Temperature Regulation This chapter explores the role of skin in vitamin D synthesis and temperature regulation. It highlights the importance of vitamin D in bone growth, especially in children, and its role in maintaining healthy bones in adults. The skin serves as a protective barrier against the environment, vital for both vitamin D production and temperature sensation.
• 02:30 - 03:30: Structure of the Skin: The Three Major Layers The chapter titled 'Structure of the Skin: The Three Major Layers' discusses how the skin functions as a sensory and regulatory organ. It explains the role of nerve receptors in sensing different types of touch, which allows us to interact with our environment. The skin also plays a crucial role in regulating body temperature, helping to keep us warm in cold conditions and cooling us when we become too warm. Furthermore, the chapter introduces the concept of the skin being composed of three major layers, setting the stage for a deeper exploration into each layer.
• 03:30 - 04:30: Focus on the Epidermis: Types of Skin Cells The chapter focuses on the epidermis, which is the topmost layer of the skin. It distinguishes between different types of skin cells that constitute the visible skin. The lecture appears to explore these cell types in more detail, likely describing their functions and significance in the integumentary system.
• 04:30 - 05:00: Stem Cells in the Epidermis This chapter focuses on the different types of cells that compose the epidermis of the skin. The key cells discussed include stem cells, keratinocytes, melanocytes, tactile cells, and dendritic cells. A detailed illustration of skin layers is presented to aid understanding, with an emphasis on exploring the role and importance of these specific cells in the epidermis.
• 05:00 - 06:00: Keratinocytes and Their Role The chapter discusses the role of keratinocytes and begins by introducing stem cells located in the basal layer of the epidermis. This specific layer is called the stratum basale, positioned where the epidermis meets the dermis.
• 06:00 - 06:30: Psoriasis and Keratinocyte Migration The chapter discusses the presence of stem cells within the epidermis that are capable of differentiating into various epidermal cells, including keratinocytes. These keratinocytes are the most abundant epidermal cells and are responsible for synthesizing keratin, a strong protein that plays a critical role in the skin's structure.
• 06:30 - 08:00: Melanocytes and Skin Color This chapter highlights the function of protein in adding strength and durability to our cells and its role in forming a protective, waterproof layer. It mentions that stem cells constantly divide by mitosis predominantly into keratinocytes, which then gradually migrate.
• 08:00 - 10:00: Environmental and Genetic Influence on Skin Color The chapter discusses the journey of cells to the skin's surface, typically taking 30 to 40 days. However, in individuals with psoriasis, this process is accelerated to just 7 to 10 days, which affects the skin's appearance.
• 10:00 - 12:00: Tactile Cells: Merkel Cells This chapter discusses the presence and role of Merkel cells within the skin, particularly focusing on the migration of cells leading to flaky and itchy skin. It mentions how these cells reach the top layer of the skin rapidly. Additionally, the chapter briefly introduces melanocytes, another type of cell found in the stratum basale, highlighting their role in producing melanin which determines skin color.
• 12:00 - 13:30: Dendritic Cells and Immune Function The chapter provides an overview of melanin, the pigment responsible for skin color, which is synthesized from the amino acid tyrosine. It distinguishes between two types of melanin: eumelanin, which results in black or brown hues, and pheomelanin, which contributes to red or orange hues. This segment also touches upon the role of melanocytes, the cells that produce melanin.
• 13:30 - 14:00: Conclusion: The Skin's Complexity and Functions The chapter discusses the process of melanin production by melanocytes, which are cells located at the bottom of the skin layer. These cells produce melanin and release it in small packets known as melanosomes. The melanosomes are then absorbed by keratinocytes, another type of skin cell. Once inside the keratinocytes, the melanosomes open up, and the melanin covers the cell's nucleus, contributing to skin pigmentation. This highlights the complexity and function of skin in terms of color and UV protection.

Integument 1 Intro and skin cells Transcription

• 00:00 - 00:30 your skin the organ that arguably you are the most familiar with because you look at it all the time you look at your hands your arms you look at your face every time you look in the mirror in fact you can see other people's organs too their integument when you look at them so your skin is called your integument it is you know this organ like you know the back of your hand if you will
• 00:30 - 01:00 but this organ has some very important functions for the human body first and foremost it's a protective barrier it is our resistance to trauma as well as resistance to infection we can bump up against something hard or something rough and we don't destroy our muscles or any
• 01:00 - 01:30 other interior tissues because our skin protects us we can touch something dirty something with a lot of bacteria on it and it's as simple as washing our hands because our skin is resistant to infection it plays an important barrier in preventing bacterial growth so it's this um it protects other organ systems too all of our organ
• 01:30 - 02:00 systems inside it's like having this outer barrier wall to protect them from the environment our skin is also important for vitamin d synthesis with this vitamin d synthesis we need this for a bone growth so it's very important in children but also than as adults as we maintain our healthy bones we also use it to sense our external
• 02:00 - 02:30 environment we have nerve receptors that can feel light touch deep touch we learn about our environment through our skin and it also helps regulate our internal body temperature it helps keep us warm if we get cold and it helps cool us if we get too warm so the skin has three major layers to it
• 02:30 - 03:00 the epidermis at the top the dermis down below and the hypodermis the deepest layer of the integument in this lecture i'm going to we're going to stay with the epidermis as we talk about the difference types of cells that make up the skin that you see so here we have a cross-section
• 03:00 - 03:30 illustration of our skin and you can as you look down this illustration you can easily see the different layers that make up our epidermis the next lecture we'll talk about the importance of these layers but for this lecture we're going to really concentrate and key in on the specific cells that make up the skin those cells are stem cells keratinocytes melanocytes tactile cells and dendritic cells
• 03:30 - 04:00 so we'll start with stem cells these stem cells are found at the basal layer of our epidermis this is a specific um layer of the epidermis called the stratum basale and if i can get my mouse working here there's my mouse moving around it is this layer right here right where the epidermis meets the dermis down below
• 04:00 - 04:30 that's where these stem cells are found right here these stem cells can become any of these epidermal cells so they're considered undifferentiated cells so the cell we see the most of and the cell that you see when you look at your skins you look in your hands are called carotenocytes they make up a vast majority of all your epidermal cells they're named because they synthesize keratin this is a strong
• 04:30 - 05:00 protein that helps to add strength and durability to our cells it also it's what helps poor form the protective layer as well as the waterproofing now from the stem cells so the stem cells divide and they they divide constantly by mitosis and a majority of them divide into these keratinocytes these cells now slowly migrate toward
• 05:00 - 05:30 the surface of the cell and it takes roughly 30 to 40 days for these cells to get up to the surface to the cells that you see now i have a note on the slide about psoriasis if you suffer from psoriasis or know someone who does instead of 30 to 40 days someone with psoriasis the carotenocytes take only 7 to 10 days to reach the surface
• 05:30 - 06:00 so that's what causes this flaky skin and itchy skin this migration of cells that gets to the top it takes only a fraction of the amount of time our next cell is also found in the stratum basale this is called a melanocyte melanocytes produce melanin and that's what makes up our skin color
• 06:00 - 06:30 so melanin is what gives us our skin color it's synthesized from a specific amino acid called tyrosine and there's two different types of melanin there's eumelanin that is a black or a brownish color and there's pheno melanin which is gives us our reddish or orangish color so the um the melanocytes
• 06:30 - 07:00 produce melanin down at the bottom we see the melanocytes they're producing melanin and then they release the melanin in little packets called melanosomes these melanosomes are taken in by the carotenocytes once inside the keratinocytes they uh they open up these melanosomes and the melanin covers the the nucleus
• 07:00 - 07:30 it covers the uh the sunny side up aspect of the nucleus if you will so it forms a cap this is important because it provides a protective barrier from the sun's uv lights see the sun's uv light if it hits the nucleus of our cells it can cause damage to our chromosomes enough damage in the right parts of our
• 07:30 - 08:00 dna can cause skin cancer so melanin is in effect a natural type of sunscreen if you will so those people who are a darker color are generally more protected from uv light than those with a lighter skin color now those with a lighter skin color their melanocytes may not uh produce as much melanin or sometimes it's
• 08:00 - 08:30 so little melanin they're lighter because you can see the connective tissue layer that's found underneath the epidermis so the connective tissue the dermis layer under the uh the epidermis is a whitish tone so that's why people without um a lot of melanin have this lighter skin color you can actually see the the connective tissue underneath
• 08:30 - 09:00 now our skin color has both an environmental as well as genetic aspect to it those populations those native populations with the darkest skin color are found along the equatorial regions of the world really between the tropic of cancer and the tropic of capricorn it's in these areas of the world that you have the most direct sunlight uh 365 days of the year
• 09:00 - 09:30 so this protective mechanism um has been evolutionary advantageous to our population to protect them from the sun's uv lights now as people migrated northward they get um they get less and less direct sunlight we get very indirect sunlight up towards the poles well now we see a need for a bit of an
• 09:30 - 10:00 interchange we don't need the protective layer as much because we get such indirect sunlight however we need more vitamin d synthesis see our skin also produces helps to produce vitamin d it's the first stage of that vitamin d production and it's the uv light of the sun that makes it happen so it increased melanin levels
• 10:00 - 10:30 actually reduces you um the production of vitamin d3 and so there was a bit of a trade-off as humans migrated northward they didn't need as much melanin but instead they needed um more more uv more access to uv for increased vitamin d production see when you're in those equatorial regions
• 10:30 - 11:00 and it's your you're exposed to high amounts of direct sun all the time you've got plenty of opportunity for vitamin d synthesis not so much towards the poles so the lighter the skin color helped with that increased vitamin d synthesis there's also a genetic component the this slide shows a genetic
• 11:00 - 11:30 mutation the blue is the genetic mutation for a lighter skin color so again along the equatorial regions we see the natural or historic genetics where we have that deeper melanin color but then in areas as people move northward they were able to track
• 11:30 - 12:00 this genetic mutation that gave rise to a lighter skin tone okay so the next type of cells are a type of tactile cells they're called merkel cells so these cells are associated with nerve endings uh these merkel cells seen in that big blue blob down there um they are always associated with some kind of sensory neuron
• 12:00 - 12:30 and this is a special type of nerve receptor one of our only that's found in the actual epidermis others are found in the dermis down below so this type of cells gives us our sensation of touch especially a very light touch so take your finger and rub it against the back of your hand ever so slightly you can feel that because of your merkle cells
• 12:30 - 13:00 now our uh we have dendritic cells these are kind of creepy if you think about it they're part of our immune system and they sneak around through our epidermis layer and guard they're they're on the lookout for pathogens they're on the lookout for toxins so they sneak around looking for things to kill
• 13:00 - 13:30 kind of creepy to think about that we have cells within our cells moving around and creeping around but kind of cool because that's one of the protective mechanisms of our body that's helping to keep us safe and guard us against pathogens the human body is really really cool