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Questions and Answers
What is the outermost layer of the hair structure referred to as?
What is the outermost layer of the hair structure referred to as?
Which layer of the hair follicle provides the primary support structure?
Which layer of the hair follicle provides the primary support structure?
What is the function of the arrector pili muscle?
What is the function of the arrector pili muscle?
Which part of the hair structure is primarily associated with production and growth?
Which part of the hair structure is primarily associated with production and growth?
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Which layer of the hair follicle is closest to the hair itself?
Which layer of the hair follicle is closest to the hair itself?
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What is one of the metabolic functions of the integumentary system?
What is one of the metabolic functions of the integumentary system?
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Which type of skin cancer is characterized as the least malignant and most common?
Which type of skin cancer is characterized as the least malignant and most common?
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What is a key characteristic of melanoma that differentiates it from other skin cancers?
What is a key characteristic of melanoma that differentiates it from other skin cancers?
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What aids in early detection of melanoma according to the ABCD rule?
What aids in early detection of melanoma according to the ABCD rule?
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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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Which risk factor is specifically associated with skin cancer?
Which risk factor is specifically associated with skin cancer?
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What type of skin cancer typically arises from keratinocytes in the stratum spinosum?
What type of skin cancer typically arises from keratinocytes in the stratum spinosum?
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What percentage of the body's blood volume can be stored in the integumentary system?
What percentage of the body's blood volume can be stored in the integumentary system?
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Which layer of the epidermis is primarily made up of dead cells filled with keratin?
Which layer of the epidermis is primarily made up of dead cells filled with keratin?
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What is the primary function of melanocytes in the epidermis?
What is the primary function of melanocytes in the epidermis?
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Which cell type in the epidermis is responsible for sensing touch?
Which cell type in the epidermis is responsible for sensing touch?
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Which layer of the epidermis contains mitotically active stem cells?
Which layer of the epidermis contains mitotically active stem cells?
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What is the characteristic feature of the stratum granulosum?
What is the characteristic feature of the stratum granulosum?
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Which cells serve as key activators of the immune system in the epidermis?
Which cells serve as key activators of the immune system in the epidermis?
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In thick skin, which layer of the epidermis is present that is absent in thin skin?
In thick skin, which layer of the epidermis is present that is absent in thin skin?
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What connects keratinocytes to each other within the epidermis?
What connects keratinocytes to each other within the epidermis?
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What type of connective tissue is found in the papillary layer of the dermis?
What type of connective tissue is found in the papillary layer of the dermis?
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What structures are primarily found in the dermal papillae?
What structures are primarily found in the dermal papillae?
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What is the primary composition of the reticular layer of the dermis?
What is the primary composition of the reticular layer of the dermis?
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Which of the following is true regarding cleavage lines in the dermis?
Which of the following is true regarding cleavage lines in the dermis?
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What role do friction ridges play in the skin?
What role do friction ridges play in the skin?
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Which type of sensory receptors is found in some dermal papillae?
Which type of sensory receptors is found in some dermal papillae?
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What are flexure lines in the skin caused by?
What are flexure lines in the skin caused by?
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Which component is NOT a function of collagen fibers in the dermis?
Which component is NOT a function of collagen fibers in the dermis?
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What type of tissue is found in the dermis layer of the skin?
What type of tissue is found in the dermis layer of the skin?
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Which of the following cells can be found in the dermis?
Which of the following cells can be found in the dermis?
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What are the two layers of the dermis?
What are the two layers of the dermis?
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What is the primary function of the arrector pili muscle?
What is the primary function of the arrector pili muscle?
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Which structure is NOT part of the skin?
Which structure is NOT part of the skin?
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What type of glands are eccrine sweat glands classified as?
What type of glands are eccrine sweat glands classified as?
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What component is responsible for binding the body together within the dermis?
What component is responsible for binding the body together within the dermis?
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In what layer would you find the cutaneous plexus?
In what layer would you find the cutaneous plexus?
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What causes striae, commonly known as stretch marks?
What causes striae, commonly known as stretch marks?
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Which pigment is primarily responsible for the color of skin?
Which pigment is primarily responsible for the color of skin?
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What is the appearance of skin affected by cyanosis?
What is the appearance of skin affected by cyanosis?
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Where does carotene most prominently accumulate in the skin?
Where does carotene most prominently accumulate in the skin?
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What condition is characterized by a yellow cast to the skin?
What condition is characterized by a yellow cast to the skin?
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What role does melanin play in skin protection?
What role does melanin play in skin protection?
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What primarily stimulates melanin production in the skin?
What primarily stimulates melanin production in the skin?
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Which skin condition occurs due to acute short-term trauma?
Which skin condition occurs due to acute short-term trauma?
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Study Notes
Skin (Integument)
- Consists of two distinct regions: epidermis (superficial epithelial tissue) and dermis (underlies epidermis, mostly fibrous connective tissue)
- Hypodermis (subcutaneous layer) is deep to the skin, not part of skin but shares functions. It's mostly adipose tissue, absorbing shock and insulating, anchoring skin to structures (mostly muscles)
Epidermis
- Keratinized stratified squamous epithelium
- Four or five distinct layers: stratum basale, stratum spinosum, stratum granulosum, stratum lucidum (only in thick skin), and stratum corneum
- Four cell types: keratinocytes, melanocytes, dendritic (Langerhans) cells, and tactile (Merkel) cells
Keratinocytes
- Produce fibrous protein keratin (most epidermis cells)
- Tightly connected by desmosomes
- 10-25% of cells in deepest epidermis
- Produce pigment melanin - packaged into melanosomes
- Protect apical surface of keratinocyte nucleus from UV damage
Dendritic (Langerhans) cells
- Macrophages (key activators of immune system)
Tactile (Merkel) cells
- Sensory touch receptors
Stratum Basale (Basal Layer)
- Deepest epidermal layer, also called stratum germinativum
- Firmly attached to dermis
- Single row of stem cells actively mitotic, producing two daughter cells
- Takes 25-45 days for one cell to move from basal layer to the surface where it dies
- One cell remains in stratum basale as a stem cell
- Melanocytes compose 10-25% of this layer
Stratum Spinosum (Prickly Layer)
- Several layers thick
- Cells contain web-like system of intermediate prekeratin filaments attached to desmosomes
- Abundant melanosomes and dendritic cells
Stratum Granulosum (Granular Layer)
- Thin (four to six cell layers)
- Cell appearance changes: cells flatten, nuclei and organelles disintegrate, keratinization begins
- Cells accumulate keratohyaline granules (help form keratin in upper layers)
- Cells accumulate lamellar granules (their water-resistant glycolipid slows water loss)
- Cells above this layer die (too far from dermal capillaries)
Stratum Lucidum (Clear Layer)
- Only in thick skin
- Thin, translucent band superficial to the stratum granulosum
- A few rows of flat, dead keratinocytes
Stratum Corneum (Horny Layer)
- 20-30 rows of dead, flat, anucleate keratinized membranous sacs
- Three-quarters of epidermal thickness
- Though dead, its cells protect deeper cells, prevent environment and water loss, abrasion, and penetration
- Provides barrier against biological, chemical, and physical assaults
Dermis
- Strong, flexible connective tissue
- Cells: fibroblasts, macrophages, mast cells, and white blood cells
- Fibers in matrix bind body together (“Hide” used to make leather)
- Contains nerve fibers, blood/lymphatic vessels
- Contains epidermal hair follicles, oil and sweat glands
- Two layers: papillary and reticular
Papillary Layer of Dermis
- Areolar connective tissue
- Collagen and elastic fibers and blood vessels
- Loose tissue — phagocytes patrol for microorganisms
- Dermal papillae – superficial peglike projections
Dermal Papillae
- Most contain capillary loops
- Some contain Meissner's corpuscles (touch receptors)
- Some contain free nerve endings (pain receptors)
- In thick skin, lie atop dermal ridges that cause epidermal ridges (friction ridges)
- Enhance gripping ability
- Contribute to the sense of touch
- Pattern is fingerprints
Reticular Layer of Dermis
- ~80% of dermal thickness
- Dense fibrous connective tissue
- Elastic fibers provide stretch-recoil properties (strength and resiliency)
- Bind water (cleavage lines because most collagen fibers run parallel to skin surface)
- Externally invisible, important to surgeons
- Incisions parallel to cleavage lines gap less and heal more readily
Flexure lines
- Dermal folds at or near joints
- Dermis is tightly secured to deeper structures
- Skin cannot slide easily for joint movement causing deep creases
- Visible on hands, wrists, fingers, soles, toes
Other Skin Markings
- Striae: silvery-white scars ("stretch marks") from extreme stretching causing dermal tears
- Blisters: from acute, short-term trauma, fluid-filled pocket that separates epidermal and dermal layers
Skin Color
- Three pigments: melanin, carotene, hemoglobin
- Melanin: only pigment made in skin (two forms- reddish-yellow to brownish-black)
- Color differences due to amount and form
- Produced in melanocytes (same relative number in all people)
- Migrates to keratinocytes to form "pigment shields"
- Freckles and pigmented moles (local accumulations of melanin)
- Sun exposure stimulates melanin production
- Sunspots (tinea versicolor) are fungal infection (not related to melanin)
- Carotene: yellow to orange pigment (most obvious in palms and soles), accumulates in stratum corneum and hypodermis, can be converted to vitamin A for vision and epidermal health
- Hemoglobin: pinkish hue of fair skin
Appendages of the Skin
- Derivatives of the epidermis: hairs and hair follicles, nails, sweat glands, and sebaceous (oil) glands
Hair
- Dead keratinized cells of hard keratin (more durable)
- Not in palms, soles, lips, nipples, portions of external genitalia
- Functions: warn of insects, physical trauma, heat loss, sunlight
- Hair pigments: melanins (yellow, rust, brown, black); trichosiderin (red hair)
- Gray/white hair: decreased melanin production, increased air bubbles in shaft
Hair Follicles
- Extend from epidermis to dermis
- Two-layered wall (part dermis, part epidermis)
- Hair bulb (expanded deep end, hair follicle receptor (root hair plexus), sensory nerve endings - touch receptors hair matrix (actively dividing area)
- Arrector pili (smooth muscle attached to follicle, responsible for "goose bumps")
- Hair papilla (dermal tissue – blood supply)
Nails
- Scalelike modifications of epidermis
- Protective cover for distal, dorsal surface of fingers and toes
- Contain hard keratin
- Nail matrix (hair growth)
Sweat Glands
- Also called sudoriferous glands
- All skin surfaces except nipples and parts of external genitalia
- ~3 million per person
- Two main types: eccrine (merocrine) and apocrine sweat glands
- Eccrine sweat glands are most numerous, abundant on palms, soles, and forehead; ducts connect to pores; function in thermoregulation (regulated by sympathetic nervous system), secretion is mostly water
- Apocrine sweat glands are larger than eccrine glands, confined to axillary and anogenital areas, their secretion contains fatty substances, proteins and are odorless until bacterial interaction = body odor, ducts empty into hair follicles, become functional at puberty
Sebaceous (Oil) Glands
- Widely distributed (not in thick skin of palms and soles)
- Most develop from hair follicles and secrete into hair follicles
- Relatively inactive until puberty (stimulated by hormones, especially androgens)
- Secrete sebum (oily holocrine secretion, bactericidal and softens hair and skin)
Functions of the Integumentary System
- Protection (chemical, physical, biological barriers)
- Body temperature regulation
- Cutaneous sensation (sensory receptors)
- Metabolic functions (vitamin D synthesis, chemical conversion carcinogens)
- Blood reservoir (up to 5% of body's blood volume)
- Excretion (nitrogenous wastes and salts in sweat)
Skin Cancer
- Most skin tumors are benign and do not metastasize
- Risk factors: overexposure to UV radiation, frequent irritation of skin
- Some lotions contain enzymes that repair damaged DNA
- Three major types: basal cell carcinoma, squamous cell carcinoma, and melanoma
- Basal cell carcinoma: least malignant, most common, stratum basale cells proliferate, slowly invade dermis and hypodermis, cured by surgical excision in 99% of cases
- Squamous cell carcinoma: second most common type, involves keratinocytes, usually scaly reddened papule, does metastasize, good prognosis if treated by radiation therapy/removed surgically
- Melanoma: cancer of melanocytes, highly metastatic and resistant to chemotherapy, treated by wide surgical excision accompanied by immunotherapy, crucial is early detection using ABCD rule (Asymmetry, Border irregularity, Color, Diameter)
Burns
- Tissue damage from heat, electricity, radiation, certain chemicals
- Denatures proteins, kills cells
- Immediate threat: dehydration, electrolyte imbalance, leads to renal shutdown and circulatory shock
- To evaluate burns: Rule of Nines (estimates volume of fluid loss)
- Burns are classified by severity: first degree (epidermal damage only, localized redness + edema), second degree (epidermal and upper dermal damage, blisters appear), third degree (entire thickness of skin involved, skin gray-white, cherry red, or blackened, not painful)
Severity and Treatment of Burns
- Critical if >25% body has second-degree, >10% third-degree burns (Face, hands, or feet bear third-degree burns)
- Treatment includes debridement, antibiotics, temporary covering, and skin grafts
Selected Imbalances, Disorders, and Diseases Affecting the Skin
- Epidermolysis bullosa: inherited disorders in which skin blisters develop in response to minor injury
- Psoriasis: common skin condition causing skin redness and irritation
- Contact dermatitis: inflammation of skin caused by direct contact irritating substance
- Pressure ulcers: area of skin breaks down from staying in one position for too long without shifting weight
- Folliculitis: inflammation of one or more hair follicles
- Acne: skin condition characterized by whiteheads, blackheads, and inflamed red pimples
- Albanism: no skin pigment
- Jaundice: common in newborns, yellow color skin/whites of eyes caused by excess bilirubin in the blood
- Other related conditions and diseases...
Developmental Aspects
- Fetal: ectoderm → epidermis; mesoderm → dermis + hypodermis; lanugo coat; vernix caseosa
- Infancy to adulthood: skin thickens, sweat/sebaceous glands activity increases, effects of environmental assaults, scaling, and dermatitis more common
- Aging: epidermal replacement slows, skin becomes thin/dry, subcutaneous fat/elasticity decrease (cold intolerance + wrinkles), increased risk of cancer (decreased numbers melanocytes/ dendritic cells), hair thinning)
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Description
Test your knowledge on the layers of the hair structure and the integumentary system's functions. This quiz covers key concepts related to skin cancer and its characteristics. Challenge yourself with questions about hair follicles, skin functions, and cancer detection.
