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Questions and Answers
What is one primary function of the skin within the integumentary system?
What is one primary function of the skin within the integumentary system?
Which type of cells in the epidermis are responsible for producing the protein keratin?
Which type of cells in the epidermis are responsible for producing the protein keratin?
What role do blood vessels in the dermis play in temperature regulation?
What role do blood vessels in the dermis play in temperature regulation?
Which of the following is NOT a component of the integumentary system?
Which of the following is NOT a component of the integumentary system?
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Why is vitamin D important for the body?
Why is vitamin D important for the body?
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Which of the following correctly describes the composition of the hypodermis?
Which of the following correctly describes the composition of the hypodermis?
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What is the main function of the nails in the integumentary system?
What is the main function of the nails in the integumentary system?
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What process do keratinocytes undergo as they move from the basement membrane to the skin surface?
What process do keratinocytes undergo as they move from the basement membrane to the skin surface?
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What is the primary function of the stratum basale?
What is the primary function of the stratum basale?
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Which layer of the epidermis contains keratinocytes and melanocytes?
Which layer of the epidermis contains keratinocytes and melanocytes?
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What is the appearance of the stratum lucidum characterized by?
What is the appearance of the stratum lucidum characterized by?
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What primarily affects skin color?
What primarily affects skin color?
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In what location would you most likely find thick skin?
In what location would you most likely find thick skin?
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What is the primary cause of erythema?
What is the primary cause of erythema?
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Which type of cells are primarily involved in producing melanin?
Which type of cells are primarily involved in producing melanin?
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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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What is the primary component of the papillary layer of the dermis?
What is the primary component of the papillary layer of the dermis?
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What function do dermal papillae serve in thick skin?
What function do dermal papillae serve in thick skin?
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What type of tissue is primarily found in the reticular layer of the dermis?
What type of tissue is primarily found in the reticular layer of the dermis?
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What is a common characteristic of striae in the dermis?
What is a common characteristic of striae in the dermis?
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Which type of hair is characterized as unpigmented and typically found on a fetus?
Which type of hair is characterized as unpigmented and typically found on a fetus?
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What is the role of arrector pili muscles associated with hair follicles?
What is the role of arrector pili muscles associated with hair follicles?
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What type of gland is a sebaceous gland classified as?
What type of gland is a sebaceous gland classified as?
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What is the primary function of the hypodermis?
What is the primary function of the hypodermis?
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Study Notes
Integumentary System
- Function: Protection, sensation, temperature regulation, vitamin D production, excretion
- Components: Skin, glands, hair, nails
Protection
-
Skin:
- Protects from mechanical damage, like abrasion and tearing
- Barrier for microorganisms and water loss
- Absorbs UV light, protecting underlying structures
- Hair: Insulator and traps particles
- Nails: Defense
Sensation
- Receptors detect heat, cold, pain, and pressure
Temperature Regulation
-
Blood Vessels:
- Dilate: Bring warm blood to the surface, increasing heat loss
- Constrict: Reduce warm blood to the surface, keeping the core warmer
- Sweating: Releases heat
- Shivering: Adds warmth
Vitamin D Production
- Role: Needed for calcium and phosphate absorption in the small intestine
-
Process:
- Precursor molecule found in the skin converts to cholecalciferol with UV exposure
- Cholecalciferol then converted to calcitriol (vitamin D) by kidneys and liver
- Sources: Can also be obtained from liver, egg yolks, and dairy products
Excretion
- Urea, uric acid, and ammonia wastes are excreted in sweat
Skin Layers
-
Epidermis:
- Superficial layer
- Stratified squamous epithelium
- Nourishment from dermis
-
Dermis: Deep layer
- Loose areolar connective tissue
- Dense irregular connective tissue
-
Hypodermis/Subcutaneous: Below dermis
- Adipose connective tissue
- Loose connective tissue
Epidermis
- Structure: Stratified squamous epithelial tissue, with basement membrane and apical surface
-
Cells:
- Keratinocytes: Produce keratin for cell hardening
- Melanocytes: Produce melanin for skin color
- Langerhans Cells: Immune cells
- Merkel Cells: Nerve endings for light touch sensation
- Growth: Mitosis at basement membrane, desquamation at surface
- Keratinization: Stem cells in basal layer undergo mitosis, pushing them towards the surface. They change shape, gather keratin, harden, and eventually die, being sloughed off.
Epidermis Strata
-
Stratum Basale (Basal Layer):
- Deepest layer; attached to the dermis
- Contains 1 layer of cuboidal or columnar cells
- Home to keratinocytes and melanocytes
- Undergoes constant mitosis, pushing cells upward for keratinization
-
Stratum Spinosum (Spiny Layer):
- 8-10 layers of flattened cells
- Desmosomes break and reform, making cells appear spiny
- Keratinization occurs
-
Stratum Granulosum (Granular Layer):
- 2-5 layers of flattened, diamond-shaped cells
- Contains protein granules called keratohyalin
- Cells begin dying
-
Stratum Lucidum (Clear Layer):
- Several dead layers
- Clear appearance due to dispersed keratohyalin
- Keratin fibers are present
- Thick skin has a more prominent lucidum, acting a UV shield
-
Stratum Corneum (Horny Layer):
- Superficial layer of dead, squamous cells
- Contains 25 or more dead, cornified cells
- Cells are sloughed off
- Provides structural strength, prevents water loss, and resists abrasion
Thick Skin
- Locations: Areas with pressure or friction (palms, soles, fingertips)
- Layers: 5 layers of epidermis
- Callus: Extra buildup of corneum due to friction
- Corn: Extra buildup of corneum over bony prominence
Thin Skin
- Locations: Most of the body, areas with hair
- Layers: 4 layers, usually no stratum lucidum
Skin Color
- Factors: Melanin pigment, blood flow, thickness of stratum corneum
Melanin
- Production: Melanocytes produce melanin, which is transferred to keratinocytes and distributed evenly.
- Functions: Skin, eye, and hair color; freckles, areola, moles, axilla, genitalia
- Distribution: None to less in lips, palms, and soles
- UV Protection: Protects against harmful UV radiation
- Factors: Determined by genetics, sun exposure, hormones
Changes in Skin Color
- Albinism: Absence of melanin
- Tanning: Increased melanin production due to UV exposure
- Pregnancy: Increased melanin production due to hormone changes
- Erythema: Reddish color due to changes in blood flow
- Cyanosis: Bluish color due to lack of blood flow
- Carotene: Yellow pigment from consuming excess plant-based carotenoids
Dermis
-
Structure: Connective tissue with 2 layers (papillary and reticular)
- Cells: Fibroblasts, adipose cells, macrophages
- Matrix: Mostly collagen fibers, some elastic and reticular fibers
- Other: Blood and lymph vessels, nerve endings, hair follicles, smooth muscles, glands.
Dermis Layer Structure
-
Papillary Layer:
- Superficial layer
- Loose areolar connective tissue
- Contains blood vessels, nerve endings, and dermal papillae
- Dermal Papillae: In thick skin, these protrusions into the epidermis create unique friction ridges or fingerprints.
-
Reticular Layer:
- Deepest layer
- Dense irregular collagenous connective tissue
- Contains hair follicles, nerve endings, and blood vessels
- Resists stretch
- Cleavage Lines: Tension lines created by elastin and collagen fibers
- Striae: Stretch marks caused by overstretching or tearing of dermal fibers
Hypodermis
- Structure: Attaches skin to underlying structures
- Composition: Loose connective tissue, mostly adipose
- Cells: Adipocytes, fibroblasts, macrophages
- Matrix: Collagen and elastin fibers
- Other: Blood vessels and nerves
- Functions: Energy storage, insulation, padding
Injections
- Subcutaneous: Common injection site, due to loose tissues
- Intramuscular: Injections into muscle
Hair
-
Types:
- Lanugo: Unpigmented hair of a fetus
- Terminal Hair: Scalp, eyelashes, eyebrows
- Vellus Hair: Hair on arms and legs. At puberty, terminal hair replaces vellus hair in the axilla, pubic region, and beard.
Hair Structure
- Shaft: Above the surface
- Root: Below the skin surface
-
Bulb: Base of the root
- Medulla: Middle axis of the hair with soft keratin
- Cortex: Outside of medulla, forms the bulk of the hair with hard keratin
- Cuticle: Outside covering
- Follicle: Invagination of the epidermis into the dermis, where hair resides.
Hair Characteristics
-
Growth: Begins at the base of the root (bulb), hair loss occurs as new hair grows.
- Alopecia: Hair loss
-
Color: Melanin is deposited into keratinocytes.
- Colors: Blond, black, brown, red, gray
Arrector Pili Muscle
- Structure: Smooth muscle attached to the hair follicle
- Function: Contracts in response to cold or emotional stimulus, causing hair to stand on end (goosebumps)
Glands
-
Sebaceous (Oil) Glands:
- Located in the dermis
- Produce sebum (oil)
- Ducts connect to the surface, often through a hair follicle
- Holocrine Glands: Secrete their product by cell rupture
- Function: Sebum prevents skin drying and protects against bacteria.
-
Sudoriferous (Sweat) Glands:
- Types: Eccrine and Apocrine
- Function: Secrete sweat for temperature regulation
-
Ceruminous (Earwax) Glands:
- Modified sweat glands in the ear canal
- Function: Secrete cerumen, a waxy substance that helps protect the ear canal.
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Description
Test your understanding of the integumentary system with this quiz. It covers the functions of the skin, hair, nails, and their roles in protection, sensation, temperature regulation, and vitamin D production. Perfect for students studying human biology!
