Podcast
Questions and Answers
What is the primary role of the epidermis in skin function?
What is the primary role of the epidermis in skin function?
- Regulates body temperature
- Acts as a physical barrier (correct)
- Facilitates vitamin D production
- Provides immune surveillance
Which cells are primarily involved in the initial division within the stratum basale?
Which cells are primarily involved in the initial division within the stratum basale?
- Merkel cells
- Keratinocytes (correct)
- Undifferentiated cells
- Melanocytes
What is the primary function of apocrine sweat glands located in the dermis?
What is the primary function of apocrine sweat glands located in the dermis?
- Regulate body temperature through evaporation
- Eliminate waste products from the body
- Secrete sebum for hair lubrication
- Produce pheromones and respond to emotional stimuli (correct)
What process begins to occur in the stratum granulosum?
What process begins to occur in the stratum granulosum?
Which of the following correctly describes desmosomes in the stratum spinosum?
Which of the following correctly describes desmosomes in the stratum spinosum?
Which of the following accurately describes terminal hairs?
Which of the following accurately describes terminal hairs?
What is primarily absent from the palms and soles concerning the dermal structure?
What is primarily absent from the palms and soles concerning the dermal structure?
What is the primary function of the skin appendages (adnexa)?
What is the primary function of the skin appendages (adnexa)?
Which type of cell is primarily associated with the sensation of touch?
Which type of cell is primarily associated with the sensation of touch?
In which phase of hair growth is the hair actively growing at a rate of about 1 cm per month?
In which phase of hair growth is the hair actively growing at a rate of about 1 cm per month?
What effect does Botox have on the body in relation to cholinergic innervation?
What effect does Botox have on the body in relation to cholinergic innervation?
How does the skin contribute to the body's immune function?
How does the skin contribute to the body's immune function?
Which epidermal layer is primarily responsible for waterproofing the skin?
Which epidermal layer is primarily responsible for waterproofing the skin?
Which type of hair is typically referred to as 'peach fuzz'?
Which type of hair is typically referred to as 'peach fuzz'?
What is the primary material that forms the physical barrier of the stratum corneum?
What is the primary material that forms the physical barrier of the stratum corneum?
What is the lifespan of a hair in the catagen phase?
What is the lifespan of a hair in the catagen phase?
Where do apocrine sweat glands primarily drain in the body?
Where do apocrine sweat glands primarily drain in the body?
What is one of the functions of subcutaneous fat in the skin?
What is one of the functions of subcutaneous fat in the skin?
What is produced by sebaceous glands, and what is its primary function?
What is produced by sebaceous glands, and what is its primary function?
Which areas of the body are primarily serviced by sebaceous glands?
Which areas of the body are primarily serviced by sebaceous glands?
What is the primary function of Langerhans cells?
What is the primary function of Langerhans cells?
Which layer serves as the glue between the dermis and epidermis?
Which layer serves as the glue between the dermis and epidermis?
What type of cells are responsible for producing collagen in the dermis?
What type of cells are responsible for producing collagen in the dermis?
Which of the following components is NOT found in the dermis?
Which of the following components is NOT found in the dermis?
Which structures are involved in thermoregulation in the skin?
Which structures are involved in thermoregulation in the skin?
What happens at the dermal-epidermal junction in conditions that cause blister formation?
What happens at the dermal-epidermal junction in conditions that cause blister formation?
Which cell type acts as mechanoreceptors predominantly found on the palms and soles?
Which cell type acts as mechanoreceptors predominantly found on the palms and soles?
Which function is NOT associated with blood vessels in the dermis?
Which function is NOT associated with blood vessels in the dermis?
What is the primary role of melanocytes in the skin?
What is the primary role of melanocytes in the skin?
What type of glands are eccrine sweat glands classified as?
What type of glands are eccrine sweat glands classified as?
Flashcards
Epidermis
Epidermis
The outermost layer of skin, providing protection from the environment and consisting of multiple layers.
Stratum Basale
Stratum Basale
The deepest layer of the epidermis where cell division occurs, leading to keratinocytes, melanocytes, and Merkel cells.
Keratinocyte
Keratinocyte
A cell type in the epidermis responsible for producing keratin, a protein that gives skin its strength and structure.
Melanocytes
Melanocytes
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Merkel Cells
Merkel Cells
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Stratum Spinosum
Stratum Spinosum
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Stratum Granulosum
Stratum Granulosum
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Stratum Corneum
Stratum Corneum
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Corneocytes
Corneocytes
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Skin Appendages (Adnexa)
Skin Appendages (Adnexa)
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Dermal-Epidermal Junction (BMZ)
Dermal-Epidermal Junction (BMZ)
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Collagen
Collagen
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Elastin
Elastin
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Dermis Blood Vessels
Dermis Blood Vessels
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Dermis Nerves
Dermis Nerves
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Eccrine Sweat Glands
Eccrine Sweat Glands
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Hair Follicles
Hair Follicles
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Sebaceous Glands
Sebaceous Glands
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Apocrine sweat glands
Apocrine sweat glands
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Acetylcholine
Acetylcholine
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Botox
Botox
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Dermis
Dermis
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Vellus hair
Vellus hair
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Terminal hair
Terminal hair
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Anagen
Anagen
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Catagen
Catagen
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Telogen
Telogen
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Study Notes
Skin Structure and Function
- Skin is the largest organ, weighing approximately 4 kg and covering 2 m².
Functions of the Skin
- Barrier to physical agents
- Protects against mechanical injury
- Prevents dehydration of the body
- Reduces UV radiation penetration
- Regulates body temperature
- Provides a surface for grip
- Acts as a sensory organ
- Acts as an outpost for immune surveillance
- Plays a role in Vitamin D production
Skin Components
- Epidermis
- Dermis
- Skin appendages (Adnexa)
- Subcutaneous fat
Epidermis: Layers
- Stratum corneum
- Stratum granulosum
- Stratum spinosum
- Stratum basale
Epidermis: Stratum basale
- Cell division starts
- Keratinocytes
- Melanocytes
- Merkel cells
Epidermis: Stratum spinosum
- Differentiation begins
- Undifferentiated cells become keratinocytes
- Desmosomes hold keratinocytes together
Epidermis: Stratum granulosum
- Differentiation continues, cells develop more keratin
- Cell destruction begins
- Waterproofing ("cementing")
Epidermis: Stratum corneum
- Corneocytes
- Cell death
- Physical barrier
- Microbiome (outermost layer?)
Epidermis Recap
- Major physical barrier ("bricks and mortar")
- Differentiation continues, forming keratin
- Undifferentiated cells constantly dividing
Other Structures of the Epidermis
- Langerhans cells: First line of skin's immunologic defense, derived from bone marrow
- Melanocytes: Pigment-producing cells, protect from UV radiation
- Merkel cells: Mechanoreceptors (more on palms and soles), Merkel cell carcinoma rare but deadly
Dermal Epidermal Junction
- Basement Membrane Zone (BMZ): Serves as the "glue" between dermis and epidermis
- Site of blister formation in many diseases
- Four regions: Hemidesmosomes, Lamina lucida, Lamina densa, Anchoring fibrils
Dermis: Composition and Components
- Provides structural integrity
- Regulates functions of cells
- Composed of collagen and elastin
- Extrafibrillar matrix
- Components include blood vessels, nerves, and appendages
Dermis: Nerves
- Touch sensation
- Hot and cold temperature detection
- Pain
- Free nerve endings
- Dermatomes
Dermis: Blood Vessels
- Superficial plexus
- Deep plexus
- Functions: Supply nutrition, regulate temperature
Dermis: Skin Appendages
- Eccrine sweat glands
- Apocrine sweat glands
- Hair follicles
- Sebaceous glands
- Nails
Dermis: Eccrine Sweat Glands
- Important for cooling
- Emotions and thermal stimuli trigger
- Cholinergic innervation
- Botox blocks acetylcholine
Dermis: Apocrine Sweat Glands
- Androgen dependent
- Axillary and anogenital areas
- Coiled tubule deep in dermis
- Drains into midportion of hair follicles
Dermis: Sebaceous Glands
- Androgen dependent (puberty)
- Produces sebum
- Part of pilosebaceous unit
- Located on face, scalp, upper trunk (not on palms or soles)
- Mucous membranes
Dermis: Hair
- Protective and decorative
- Entire body except palms and soles
- Keratinous hair shaft pushes through epidermis
- Basal cells at bottom of matrix
- Color by melanin
- Follicle attached to arrector pili muscles
Dermis: Hair Types
- Lanugo hairs ("baby fur"): Normally shed before birth
- Vellus hairs ("peach fuzz"): Covers most of the body
- Terminal hairs: Longer, darker, thicker (eyebrows, eyelashes, scalp)
Dermis: Hair Growth Phases
- Anagen (growth): ~1 cm/month, duration varies by location
- Catagen (transitional): 3-4 weeks for scalp hair, ~50-100 scalp follicles switch every day
- Telogen (resting): ~3 months for scalp hair, 25-100 hairs shed daily
Not-in-the-dermis: Nails
- Hard-packed keratin
- From matrix of dividing epidermal cells
- Facilitate fine grasping and pinching
- Nail plate thickness 0.3-0.65 mm
- Fingernails grow 0.1 mm/day, toenails slower
Subcutaneous Fat
- Lies between dermis and fascia
- Insulates
- Cushions
- Energy reservoir
- Hormone messaging
- Wound healing support, hair follicle growth, and photoageing protection
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