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Questions and Answers
What is the primary function of melanocytes in the skin?
The epidermis is vascularized and contains blood vessels.
False
Name the layer of skin that anchors all structures to the fascia.
subcutaneous layer
The largest organ in the human body makes up _____ of body weight.
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Match the following skin cell types to their functions:
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What are the primary functions of hair?
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Squamous cell carcinomas involve cells in the stratum basale.
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What is the most common type of skin cancer?
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Hair protects the scalp from UV radiation and the eyes and nasal cavity from _____ invasion.
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Match the following skin cancer types with their characteristics:
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What layer of the hair is responsible for the majority of hair's bulk?
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The cuticle of the hair is composed of cylindrical cells that allow for elasticity.
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The deepest layer of the hair structure is called the _____ .
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What type of connective tissue makes up the reticular region of the dermis?
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The stratum lucidum is found in all areas of the skin.
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What is the main component that gives skin its strength and flexibility?
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The epidermis consists of ____ strata in most body areas and ____ strata in high abrasion areas.
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Match the layers of the epidermis with their description:
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Which layer of the epidermis contains keratin intermediate filaments that provide a strong foundation?
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Melanin production in the skin is equal among all individuals.
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What process do cells in the stratum granulosum undergo before dying?
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Fingerprints are formed by epidermal ridges and are unique due to the shape of the _____ _____.
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What causes a person's skin to tan?
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Match the stratums of the skin with their main functions:
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Tattoos fade quickly because they are applied to the epidermis.
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What structure helps in sensing touch and pain in the skin?
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The accumulation of melanin can lead to the formation of _______ and age spots.
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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 fascinating world of the integumentary system, which includes skin, hair, nails, and sensory receptors. Learn about the various functions of skin, its structure, and the roles of different cell types in maintaining skin health. This quiz will enhance your understanding of how this vital system protects and regulates the body.
