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What is the largest organ of the human body?
The epidermis is vascularized.
False
What are the primary functions of the integumentary system?
Regulate body temperature, protect the body, sense signals, excrete and absorb chemicals, store blood and energy, synthesize vitamin D.
The deep layer of the skin that is made of connective tissue is called the _________.
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Match the following cell types with their functions:
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Which layer of skin anchors all structures to the fascia?
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Melanin protects DNA by absorbing ultraviolet light.
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What type of epithelium makes up the epidermis?
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The skin performs ________ to eliminate waste products.
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Which statement about UV light is correct?
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What is the function of hair in relation to the scalp?
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Hair is primarily composed of living cells.
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What are the three layers of hair?
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The outer layer of hair roots is known as the hair ______.
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Which type of skin cancer involves the stratum spinosum?
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Malignant melanomas arise from keratinocytes.
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What does the arrector pili muscle do?
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Match the following terms related to skin cancer with their descriptions:
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Hair traps air close to the skin to minimize _______ loss.
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Which of the following structures is NOT part of the integumentary system?
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What is the main function of tactile epithelial cells?
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The stratum corneum is the deepest layer of the epidermis.
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What term is used to describe the process of programmed cell death that occurs in the stratum granulosum?
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The epidermis contains approximately ____ layers in thin skin and ____ layers in thick skin.
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Match the following layers of the skin with their descriptions:
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What role do dermal papillae play in the skin?
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Everyone has the same number of melanocytes regardless of skin color.
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What is the primary composition of the reticular region of the dermis?
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After a tan fades, the skin is replaced by cells that have ____ melanin production.
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What is the role of tyrosinase in skin pigmentation?
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Study Notes
Integumentary System Overview
- Comprises skin, hair, nails, associated glands, and sensory receptors.
- Skin is the largest organ, constituting 7% of body weight.
- Skin thickness varies from 0.5 mm (eyelids) to 4 mm (heels).
- Epidermis is the surface layer, avascular, sitting atop the vascularized dermis.
- Subcutaneous layer (hypodermis) anchors skin structures to underlying fascia and contains pressure receptors.
Functions of the Integumentary System
- Regulates body temperature.
- Protects against external insults.
- Senses environmental signals.
- Facilitates excretion and absorption of chemicals.
- Stores blood and energy.
- Synthesizes vitamin D.
The Epidermis
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Composed of keratinized stratified squamous epithelium with various cell types:
- Keratinocytes: Produce keratin and waterproofing lamellar granules.
- Melanocytes: Contain melanin, protecting DNA from UV damage; vary in melanin secretion produce skin color differences.
- Langerhans cells: UV-sensitive macrophages that perform phagocytosis.
- Tactile epithelial cells: Sensitive to touch.
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Epidermis is subdivided into strata based on keratinocyte maturity:
- Four strata in most skin; five strata in high abrasion areas (palms, soles).
- Layers are stratum basale, stratum spinosum, stratum granulosum, stratum corneum, and stratum lucidum (only in thick skin).
Structure of Strata
- Stratum Basale: Deepest layer with stem cells for replenishment; rich in keratin intermediate filaments; characterized by large nuclei and ribosomes.
- Stratum Spinosum: Provides strength; contains 8-10 layers of flat keratinocytes with tougher keratin IFs; fewer cells divide.
- Stratum Granulosum: Seals the epidermis; consists of 3-5 layers of dying cells, producing keratohyalin and lipids that seal underlying layers.
- Stratum Corneum: Most superficial layer with dead, overlapping cells that slough off; replenished by the stratum basale.
- Stratum Lucidum: Clear layer in thick skin, made of dead keratinocytes providing additional support.
Dermis Structure
- Made of dense connective tissue with great tensile strength.
- Papillary region: Upper 20% composed of areolar connective tissue; contains dermal papillae with capillaries and sensory neurons.
- Reticular region: Lower 80% made of dense irregular connective tissue; contains glands, nerves, and blood vessels; provides resistance to stretching and shear.
Fingerprints and Skin Color
- Formed by epidermal ridges shaped by dermal papillae; unique to individuals.
- Differences in skin color due to varying amounts of melanin secreted by melanocytes; everyone has similar numbers of melanocytes.
Melanin and Skin Protection
- Tyrosinase enzyme in melanocytes increases melanin production upon UV exposure creating a tan.
- Tans fade as skin cells die and are replaced by less pigmented cells.
Accessory Structures: Hair
- Functions include protection, insulation, and sensory functions.
- Hair anatomy includes the root embedded in the dermis, shaft above the skin, and three layers (medulla, cortex, cuticle).
- Hair follicles consist of epithelial tissue and a matrix for growth; affected by arrector pili muscles which respond to cold or fear.
Skin Cancer Awareness
- Basal cell carcinoma: Most common, arising from stratum basale, generally benign.
- Squamous cell carcinoma: Arises from stratum spinosum, represents 20% of skin cancers.
- Malignant melanoma: Develops from melanocytes; more aggressive type.
Summary of Integumentary System Functions
- Protects against abrasion, desiccation, irradiation, and invasion.
- Skin color variations stem from melanin secretion differentials.
- Critical for wound healing and maintaining homeostasis.
- Burns can lead to serious complications like edema and sepsis.
- Excessive UV exposure increases the risk of skin cancer through uncontrolled cell proliferation.
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Description
Explore the intricate structures of human skin and hair in this quiz. Learn about the layers of the skin, including the epidermis, dermis, and subcutaneous layer, as well as associated glands and sensory receptors. Test your knowledge on the largest organ of the body, its functions, and characteristics.
