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Questions and Answers
What type of secretion do sebaceous glands primarily release?
What type of secretion do sebaceous glands primarily release?
Which gland in the integumentary system is responsible for producing cerumen?
Which gland in the integumentary system is responsible for producing cerumen?
Which component of skin provides a chemical barrier against bacterial growth?
Which component of skin provides a chemical barrier against bacterial growth?
What is the primary function of apocrine sweat glands?
What is the primary function of apocrine sweat glands?
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Which of the following is NOT a function of the integumentary system?
Which of the following is NOT a function of the integumentary system?
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At what life stage do apocrine sweat glands begin to function?
At what life stage do apocrine sweat glands begin to function?
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What is the only pigment produced by the skin?
What is the only pigment produced by the skin?
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Which factor does NOT influence the differences in skin color?
Which factor does NOT influence the differences in skin color?
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What characteristic allows the skin to act as a barrier to water-soluble substances?
What characteristic allows the skin to act as a barrier to water-soluble substances?
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What process is enhanced during UV exposure that increases melanin production?
What process is enhanced during UV exposure that increases melanin production?
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Which of the following protects against UV radiation damage?
Which of the following protects against UV radiation damage?
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What occurs to melanin granules to shield DNA from UV radiation?
What occurs to melanin granules to shield DNA from UV radiation?
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What is the primary function of mammary glands?
What is the primary function of mammary glands?
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What happens during the tanning process?
What happens during the tanning process?
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Which type of sweat is produced by apocrine sweat glands?
Which type of sweat is produced by apocrine sweat glands?
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Albinism is characterized by which condition?
Albinism is characterized by which condition?
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What structure contains concentric layers of supporting cells around a sensory nerve ending?
What structure contains concentric layers of supporting cells around a sensory nerve ending?
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Which layer of the skin is primarily responsible for the yellow to orange pigment accumulation?
Which layer of the skin is primarily responsible for the yellow to orange pigment accumulation?
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Which of the following epidermal derivatives does NOT include hair?
Which of the following epidermal derivatives does NOT include hair?
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Which of the following is NOT true regarding melanocytes?
Which of the following is NOT true regarding melanocytes?
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What is a function of dendritic cells in the epidermis?
What is a function of dendritic cells in the epidermis?
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Which of the following correctly describes the response to elevated body temperature?
Which of the following correctly describes the response to elevated body temperature?
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What occurs in the skin during exposure to a cold external environment?
What occurs in the skin during exposure to a cold external environment?
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What is one of the metabolic functions of the skin?
What is one of the metabolic functions of the skin?
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Which type of receptor is responsible for detecting touch and pressure sensations in the skin?
Which type of receptor is responsible for detecting touch and pressure sensations in the skin?
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What role do dermal macrophages play in the immune response?
What role do dermal macrophages play in the immune response?
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How much fluid is lost per day through insensible perspiration?
How much fluid is lost per day through insensible perspiration?
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What is a characteristic of sensible perspiration?
What is a characteristic of sensible perspiration?
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What is a significant feature of the cutaneous sensory receptors?
What is a significant feature of the cutaneous sensory receptors?
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Which statement about the blood reservoir function of the skin is correct?
Which statement about the blood reservoir function of the skin is correct?
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What is the primary function of keratin in the skin?
What is the primary function of keratin in the skin?
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Where are melanocytes primarily located within the epidermis?
Where are melanocytes primarily located within the epidermis?
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How long does it take for a cell to migrate from the stratum basale to the surface of the skin?
How long does it take for a cell to migrate from the stratum basale to the surface of the skin?
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What type of connective tissue predominantly composes the dermis?
What type of connective tissue predominantly composes the dermis?
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What characteristic distinguishes thick skin from thin skin?
What characteristic distinguishes thick skin from thin skin?
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What is the primary function of the stratum corneum?
What is the primary function of the stratum corneum?
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Which layer of the dermis is associated with pain receptors?
Which layer of the dermis is associated with pain receptors?
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What type of cells in the epidermis are primarily responsible for cell-mediated immunity?
What type of cells in the epidermis are primarily responsible for cell-mediated immunity?
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What do the dermal papillae contain that is critical for skin sensitivity?
What do the dermal papillae contain that is critical for skin sensitivity?
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What layer of the epidermis is characterized as the 'prickly layer'?
What layer of the epidermis is characterized as the 'prickly layer'?
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What is the main role of the hypodermis?
What is the main role of the hypodermis?
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What is primarily responsible for the waterproof properties of the epidermis?
What is primarily responsible for the waterproof properties of the epidermis?
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Which layer of skin is NOT considered a part of the skin itself?
Which layer of skin is NOT considered a part of the skin itself?
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What is the function of the fibroblasts found in the dermis?
What is the function of the fibroblasts found in the dermis?
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What is one of the primary functions of hair on the head?
What is one of the primary functions of hair on the head?
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What is the function of nose hairs?
What is the function of nose hairs?
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What type of keratin is found in hair, making it tougher and more durable?
What type of keratin is found in hair, making it tougher and more durable?
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Where does hair growth primarily occur?
Where does hair growth primarily occur?
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What type of cells primarily make up the medulla of hair?
What type of cells primarily make up the medulla of hair?
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What role do hair follicles play in hair structure?
What role do hair follicles play in hair structure?
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What is the arrector pili muscle responsible for?
What is the arrector pili muscle responsible for?
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Which layer of hair contains several flattened cells?
Which layer of hair contains several flattened cells?
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What type of sweat gland is most numerous and located on palms and soles?
What type of sweat gland is most numerous and located on palms and soles?
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What structure provides blood supply to the hair follicle?
What structure provides blood supply to the hair follicle?
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What layer of hair is the outermost and consists of single overlapping cells?
What layer of hair is the outermost and consists of single overlapping cells?
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What is a characteristic of eccrine sweat glands?
What is a characteristic of eccrine sweat glands?
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Which component of hair is absent in fine hairs?
Which component of hair is absent in fine hairs?
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What is the primary role of hair receptors found in the hair bulb?
What is the primary role of hair receptors found in the hair bulb?
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Study Notes
Skin Overview
- Skin is the largest organ of the body.
- Composed of two main regions: epidermis and dermis.
Epidermis
- Made up of epithelial tissue; avascular (lacks blood vessels).
Dermis
- Located beneath the epidermis; primarily fibrous connective tissue; vascularized (contains blood vessels).
- Nutrients are diffused from the dermis to the epidermis.
Hypodermis (Superficial Fascia)
- Not part of the skin; subcutaneous layer composed mostly of adipose tissue.
- Functions: absorbs shock, stores fat, insulates, and anchors skin to underlying muscles.
Fascia
- A fibrous membrane that covers, supports, and separates muscles.
Cells of the Epidermis
- Keratinocytes: The majority of epidermal cells; produce keratin.
- Melanocytes: Located in deeper epidermal layers; synthesize melanin to provide UV protection.
- Dendritic (Langerhans) Cells: Function as macrophages in the skin.
- Tactile (Merkel) Cells: Serve as sensory touch receptors.
Layers of the Epidermis
- Thick Skin: Found in areas subjected to abrasion (e.g., palms, fingertips); contains five strata.
- Thin Skin: Contains four layers.
Stratum Basale (Basal Layer)
- Deepest layer; single layer of actively mitotic cuboidal stem cells.
- Melanocytes comprise about 10-25% of this layer; produce melanin for UV protection.
Stratum Spinosum (Prickly Layer)
- Several cell layers thick; contains pre-keratin bundles.
- Characterized by dendritic cells and abundant melanin granules.
Stratum Granulosum (Granular Layer)
- Thin layer (1-5 cell layers); cells begin to flatten and disintegrate.
- Accumulation of keratohyaline and lamellar granules, which contain water-resistant glycolipids.
Stratum Lucidum (Clear Layer)
- Present only in thick skin; superficial to the stratum granulosum.
- Composed of 2-3 rows of flat, dead keratinocytes.
Stratum Corneum
- Thickest layer (20-30 rows of dead, flat, keratinized cells).
- Provides protective barrier against abrasion, penetration, and water loss through keratin and glycolipids.
Cell Differentiation in Epidermis
- Transition from stratum basale to stratum corneum; cells shed about 50,000 per minute as dander and dandruff.
Dermis
- Comprised of connective tissue that supports and binds epidermis to hypodermis.
- Houses blood vessels, nerves, glands, and hair follicles.
Papillary Dermis
- The upper layer of the dermis; contains areolar connective tissue.
- Features dermal papillae with capillary loops and Meissner's corpuscles for light touch sensitivity.
Reticular Dermis
- Constitutes about 80% of dermal thickness; made of dense irregular connective tissue.
- Contains collagen fibers for strength and elastic fibers for stretchability.
- Includes cleavage lines (tension lines) and flexure lines near joints.
Skin Color
- Determined by pigments: melanin (only skin-produced pigment), carotene (yellow-orange), and hemoglobin (red in blood).
Melanin Synthesis
- Tyrosinase enzyme converts tyrosine to melanin; melanin protects against UV damage.
- Number of melanocytes does not vary by gender or race; differences arise from pigment type and distribution.
Tanning and Albinism
- Tanning results from UV exposure stimulating melanin production.
- Albinism: Melanin production is severely reduced or absent.
Epidermal Derivatives
- Includes hair and hair follicles, nails, sweat glands, and sebaceous (oil) glands.
Hair (Pili)
- Composed of dead keratinized cells; absent from specific areas like palms and soles.
- Serves various functions including protection and thermoregulation.### Functions of Hair
- Warns of insects crawling on the skin, serving as a sensory function.
- Hair on the head acts as a barrier against physical trauma, reduces heat loss, and protects from sunlight.
- Eyelashes protect the eyes from debris and small particles.
- Nose hairs filter and trap particles, preventing entry into the respiratory system.
Characteristics of Hair
- Hard keratin in hair makes it tougher and more resilient compared to soft keratin in the skin.
- Hair cells do not flake off like skin cells.
- The hair root is embedded within the skin, while the shaft is visible above the surface.
Structure of Hair
- Medulla: Central core composed of large cells and air spaces, containing soft keratin; absent in fine hairs.
- Cortex: Major component of hair, consists of several layers of flattened cells.
- Cuticle: Outermost layer, made of a single layer of overlapping cells.
Hair Follicle Anatomy
- Extends from the epidermis surface to the dermis, consisting of a two-layered wall formed by dermis and epidermis.
- Hair Bulb: Deep, expanded part containing sensory nerve endings (root hair plexus).
- Hair Papilla: Dermal tissue supplying blood to the hair.
Hair Follicle Components
- Peripheral Connective Tissue Sheath: Derived from the dermis.
- Glassy Membrane: Serves as the basement membrane for the epithelial root sheath.
- Epithelial Root Sheath: Contains external root sheath (continuation of epidermis) and internal root sheath (derived from matrix cells).
- Hair Matrix: Location of dividing cells adjacent to the hair papilla.
- Arrector Pili Muscle: Smooth muscle causing "goose bumps" by contracting.
Nails
- Nails are scale-like modifications of the epidermis providing protection over the distal phalanges.
- Composed of hard keratin with growth occurring at the nail matrix.
Sweat Glands
- Two types: Eccrine (merocrine) and Apocrine glands.
- Eccrine Sweat Glands: Most numerous, found on the soles, palms, and forehead; contribute to thermoregulation through merocrine secretion.
- Apocrine Sweat Glands: Located in axillary and anogenital regions, secrete viscous sweat that contains fatty substances and proteins, activated at puberty.
Modified Apocrine Sweat Glands
- Ceruminous Glands: Found in the external ear canal, secrete cerumen (earwax) to deter insects and block foreign material.
- Mammary Glands: Specialized to secrete milk.
Sebaceous Glands
- Absent in thick skin (palms, soles); associated with hair follicles.
- Simple branched alveolar glands secreting sebum via holocrine secretion that acts as a protective film, preventing drying and keeping the skin soft.
Functions of the Integumentary System
- Protection: Skin serves as the body's primary defense against environmental hazards.
- Body Temperature Regulation: Thermoregulation through sweat and blood vessel dilation/constriction.
- Cutaneous Sensation: Receptors enable touch, pressure, temperature, and pain sensing.
- Metabolic Functions: Involves synthesis of vitamin D precursor and collagenase.
- Blood Reservoir: Holds up to 5% of the body's blood volume.
- Excretion: Eliminates nitrogenous wastes and salts through sweat.
Protection Mechanisms
- Chemical Barriers: Skin secretions maintain a low pH, inhibiting bacterial growth; melanin provides UV protection.
- Physical Barriers: Stratum corneum's dead, flat cells and lipids block most substances.
- Biological Barriers: Dendritic cells and dermal macrophages present foreign antigens to the immune system.
Temperature Regulation
- Normal perspiration around 500 ml/day; increased sweating and blood vessel dilation cools the body during heat.
- Constriction of dermal blood vessels retains heat in cold environments.
Sensation and Responses
- Exteroceptors enable cutaneous sensory perception; motor information leads to reflex actions like sweating and goosebumps.
Other Functions
- Metabolically synthesizes essential compounds and facilitates hormone activation.
- Acts as a waste excretion system, expelling materials through sweat.
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Description
Test your knowledge on the Integumentary System, focusing specifically on the structure and function of the skin. This quiz covers the epidermis and dermis, highlighting their composition and distinct characteristics. Perfect for students studying anatomy and physiology.
