The Epidermis
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The Epidermis

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Questions and Answers

Which layer of the epidermis contains cells that participate in the immune response?

  • Stratum basale
  • Stratum spinosum (correct)
  • Stratum lucidum
  • Stratum granulosum

    • Which layer of the epidermis is responsible for the formation of protective, superficial layers of cells filled with keratin?

  • Stratum lucidum
  • Stratum granulosum
  • Stratum basale
  • Stratum corneum (correct)

    • What is the basic structural component of hair and nails in humans?

  • Keratin (correct)
  • Collagen
  • Elastin
  • Melanin

    • Which layer of the epidermis is only present in thick skin?

    <p>Stratum lucidum</p> Signup and view all the answers

    Which layer of the epidermis forms epidermal ridges that extend into the dermis?

    <p>Stratum basale</p> Signup and view all the answers

    Which cells dominate the epidermis and form several layers?

    <p>Keratinocytes</p> Signup and view all the answers

    What is the main function of the epidermis?

    <p>Provides physical protection for the dermis</p> Signup and view all the answers

    Which layer of the epidermis is responsible for the synthesis of pigment by melanocytes?

    <p>Stratum basale</p> Signup and view all the answers

    What is the process of the formation of protective, superficial layers of cells filled with keratin called?

    <p>Keratinization</p> Signup and view all the answers

    Which layer of the epidermis is responsible for insensible perspiration?

    <p>Stratum corneum</p> Signup and view all the answers

    Which layer of the epidermis is avascular and relies on the diffusion of nutrients and oxygen from capillaries within the dermis?

    <p>Epidermis</p> Signup and view all the answers

    Which layer of the epidermis contains the body's most abundant epithelial cells?

    <p>Stratum basale</p> Signup and view all the answers

    Which layer of the epidermis is responsible for the synthesis of pigment by melanocytes?

    <p>Stratum basale</p> Signup and view all the answers

    Which layer of the epidermis forms epidermal ridges that extend into the dermis?

    <p>Stratum basale</p> Signup and view all the answers

    Which layer of the epidermis contains cells that participate in the immune response?

    <p>Stratum spinosum</p> Signup and view all the answers

    Which layer of the epidermis is only present in thick skin?

    <p>Stratum lucidum</p> Signup and view all the answers

    What is the process of the formation of protective, superficial layers of cells filled with keratin called?

    <p>Keratinization</p> Signup and view all the answers

    Which layer of the epidermis is responsible for insensible perspiration?

    <p>Stratum corneum</p> Signup and view all the answers

    Which layer of the epidermis contains tactile (Merkel) cells?

    <p>Stratum basale</p> Signup and view all the answers

    What is the basic structural component of hair and nails in humans?

    <p>Keratin</p> Signup and view all the answers

    What is the main function of the epidermis?

    <p>Physical protection and prevention of water loss</p> Signup and view all the answers

    What is the name of the protein that is a tough, fibrous protein and the basic structural component of hair and nails in humans?

    <p>Keratin</p> Signup and view all the answers

    What is the name of the protein made by keratinocytes in the stratum granulosum that promotes dehydration of the cell as well as aggregation and cross-linking of the keratin fibers?

    <p>Keratohyalin</p> Signup and view all the answers

    What is the name of the growth factor that promotes the divisions of basal cells in the stratum basale and stratum spinosum, as well as accelerates the production of keratin in differentiating keratinocytes?

    <p>Epidermal Growth Factor (EGF)</p> Signup and view all the answers

    Explain the process of keratinization and its role in the formation of protective layers in the epidermis.

    <p>Keratinization, or cornification, is the formation of protective, superficial layers of cells filled with keratin. This process takes place on all exposed skin surfaces except the anterior surfaces of the eyes. The dead cells in each layer of the stratum corneum remain tightly interconnected by desmosomes, creating water-resistant layers.</p> Signup and view all the answers

    Describe the role of epidermal growth factor (EGF) in the epidermis and its source of production.

    <p>EGF is produced by the salivary glands and glands of the duodenum. It promotes the divisions of basal cells in the stratum basale and stratum spinosum, accelerates the production of keratinization in differentiating keratinocytes, and stimulates epidermal development and repair after injury.</p> Signup and view all the answers

    Discuss the characteristics and functions of the stratum lucidum in the epidermis.

    <p>The stratum lucidum is a glassy, clear layer that covers the stratum granulosum, found only in thick skin. Its cells are flattened, densely packed, largely without organelles, and filled with keratin. It contributes to the toughness and water resistance of the skin.</p> Signup and view all the answers

    Study Notes

    Epidermis

    • The epidermis is a stratified squamous epithelium that provides physical protection, prevents water loss, and keeps microorganisms out of the body.

    Characteristics of Epidermis

    • Avascular, relying on diffusion of nutrients and oxygen from dermal capillaries
    • Epidermal cells with high metabolic demands are found close to the basement membrane
    • Superficial cells are dead

    Cells of the Epidermis

    • Keratinocytes dominate the epidermis, forming multiple layers and containing keratin
    • Keratin is a tough, fibrous protein also found in hair and nails

    Layers of the Epidermis

    • Thin skin has 4 layers, covering most of the body
    • Thick skin has 5 layers, covering palms of hands and soles of feet

    Stratum Basale

    • The deepest layer of the epidermis
    • Dominated by basal cells (stem cells) that divide to replace superficial keratinocytes
    • Contains melanocytes that synthesize pigment, tactile (Merkel) cells, and hemidesmosomes that attach to the basement membrane

    Stratum Spinosum

    • Keratinocytes bound together by desmosomes
    • Contains dendritic cells (Langerhans cells) that stimulate defense against microorganisms and superficial skin cancer

    Stratum Granulosum

    • Cells stop dividing and start making large amounts of keratin
    • Cells grow thinner, flatter, and their plasma membranes thicken and become less permeable
    • Keratohyalin promotes dehydration and aggregation of keratin fibers

    Stratum Lucidum

    • Only found in thick skin
    • A glassy, clear layer with flattened, densely packed cells filled with keratin

    Stratum Corneum

    • The exposed surface of both thick and thin skin
    • Contains 15-30 layers of keratinized cells
    • Dead cells remain tightly interconnected by desmosomes
    • Cells are shed in large groups or sheets rather than individually

    Epidermal Growth Factor (EGF)

    • Produced by salivary glands and duodenal glands
    • Promotes divisions of basal cells, accelerates keratin production, and stimulates epidermal development and repair after injury

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    Description

    Test your knowledge of the epidermis with this quiz. Explore the functions and characteristics of the epidermal layer, including its role in providing protection, preventing water loss, and maintaining a barrier against microorganisms.

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