Podcast
Questions and Answers
Which type of tissue primarily composes the epidermis?
Which type of tissue primarily composes the epidermis?
- Simple cuboidal epithelium
- Stratified squamous epithelium (correct)
- Adipose tissue
- Dense connective tissue
The epidermis contains blood vessels to directly supply nutrients to its cells.
The epidermis contains blood vessels to directly supply nutrients to its cells.
False (B)
In which layer of the epidermis does mitosis primarily occur?
In which layer of the epidermis does mitosis primarily occur?
stratum basale
__________ are the most abundant cells in the epidermis, accounting for approximately 90% of the cell population.
__________ are the most abundant cells in the epidermis, accounting for approximately 90% of the cell population.
Match the epidermal cell type with its primary function:
Match the epidermal cell type with its primary function:
Which layer of the epidermis is only found in thick skin?
Which layer of the epidermis is only found in thick skin?
The stratum corneum is composed of living, actively dividing cells.
The stratum corneum is composed of living, actively dividing cells.
What is the primary function of melanin produced by melanocytes?
What is the primary function of melanin produced by melanocytes?
Langerhans cells are a type of fixed __________ that protect the skin through phagocytosis.
Langerhans cells are a type of fixed __________ that protect the skin through phagocytosis.
Which of the following best describes the main function of the stratum spinosum?
Which of the following best describes the main function of the stratum spinosum?
The stratum granulosum is the deepest layer of the epidermis where stem cells reside.
The stratum granulosum is the deepest layer of the epidermis where stem cells reside.
What structural adaptation allows the cells of the stratum spinosum to appear 'spiny' under a microscope?
What structural adaptation allows the cells of the stratum spinosum to appear 'spiny' under a microscope?
The mnemonic "Come, Let's Get Sun Burned" helps to remember the order of the epidermal layers, with "C" representing the Stratum __________.
The mnemonic "Come, Let's Get Sun Burned" helps to remember the order of the epidermal layers, with "C" representing the Stratum __________.
Which of the following is the correct order of epidermal layers, from deepest to most superficial?
Which of the following is the correct order of epidermal layers, from deepest to most superficial?
Merkel cells function independently without interacting with sensory neurons.
Merkel cells function independently without interacting with sensory neurons.
Flashcards
Epidermis
Epidermis
The outermost layer of the integument, composed of stratified squamous epithelium with keratin.
Keratinocytes
Keratinocytes
Main cells of the epidermis that produce keratin, providing protection.
Melanocytes
Melanocytes
Epidermal cells that produce melanin to protect against UV damage.
Langerhans Cells
Langerhans Cells
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Merkel Cells
Merkel Cells
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Stratum Corneum
Stratum Corneum
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Stratum Lucidum
Stratum Lucidum
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Stratum Granulosum
Stratum Granulosum
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Stratum Spinosum
Stratum Spinosum
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Stratum Basale
Stratum Basale
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Study Notes
- The epidermis is the outermost layer of the integument.
- It is made of stratified squamous epithelium with keratin.
- This design tolerates friction and protects against injury, chemicals, and infection.
- The epidermis has high cellularity, with tightly packed cells.
- As an epithelial tissue, it is avascular.
- Areolar connective tissue beneath provides oxygen and nutrients.
- Mitosis occurs near the basement membrane, with cells moving toward the surface as they age.
- Mitosis plays a role in repair, growth, and development.
- Keratinocytes make up 90% of the epidermal cells.
- Melanocytes produce melanin, protecting against UV damage.
- Langerhans cells are fixed macrophages that protect the skin.
- Merkel cells form touch receptors with sensory neurons.
Epidermal Cell Types
- Keratinocytes: 90% of epidermal cells; produce keratin and contain many free ribosomes
- They start as cuboidal, become polygon-shaped, and flatten with age.
- They form the stratified squamous epithelium.
- Melanocytes: 7% of epidermal cells; produce melanin
- Melanin protects keratinocytes against UV damage (wear hats, avoid midday sun, use sunblock).
- Langerhans Cells (Epidermal Dendritic Cells): fixed macrophages that protect the skin
- They use phagocytosis to remove damaged cells.
- Merkel Cells (Tactile Cells): form touch receptors with sensory neurons
Epidermal Layers (in Thick Skin)
- Mnemonic: Come Let's Get Sun Burned
- Stratum corneum ("C"): the surface layer of dead, keratin-filled cells that can slough off
- Stratum lucidum ("L"): a clear layer of anucleate cells found only in thick skin
- Stratum granulosum ("G"): contains cells with many keratin granules in the cytoplasm, where free ribosomes synthesize keratin to fill the aging cells
- Stratum spinosum ("S"): tightly bound polygon-shaped cells with spiky intercellular connections
- Stratum basale ("B"): the stem cell-rich layer critical for epidermal cell regeneration
- Mitotic phases are observed in this layer.
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