Integumentary System Overview Flashcards

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Integumentary system

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The organ system that includes the skin and its accessory structures (hair, nails, glands) and cutaneous membranes. It provides protection, temperature regulation, sensation, vitamin D precursor synthesis, and excretion.

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Epidermis

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Outer, avascular layer of skin composed of epithelial tissue. It provides protection against environmental hazards and is organized into multiple strata that regenerate cells from the deepest layer.

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Keratinocytes

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The most abundant epidermal cells; produce the protein keratin, which makes the skin water-resistant. They migrate from the stratum basale to the surface and become part of the stratum corneum.

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Melanocytes

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Pigment-producing cells in the epidermis that synthesize melanin. Melanin contributes to skin color and provides UV protection by absorbing radiation.

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Merkel cells

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Specialized epithelial cells involved in light touch sensation and connected to nerve endings.

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Dendritic (Langerhans) cells

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Epidermal immune cells that act as sentinels, initiating immune responses to pathogens and anomalies in the skin.

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Stratum basale

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Deepest epidermal layer containing stem cells that divide to produce new keratinocytes and accessory structures.

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Stratum corneum

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Outermost epidermal layer composed of dead, keratinized cells that provide a tough, waterproof barrier.

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Stratum lucidum

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Clear layer found only in thick skin, between the stratum granulosum and stratum corneum.

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Dermis

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Thick, supportive layer beneath the epidermis containing connective tissue, blood vessels, nerves, glands, and hair follicles.

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Papillary layer

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Superficial dermal layer with dermal papillae that supplies the epidermis with capillaries, lymphatics, and sensory neurons.

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Reticular layer

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Deeper dermal layer rich in dense irregular connective tissue; provides strength and elasticity to the skin.

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Meissner’s corpuscles

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Tactile receptors located in dermal papillae that detect light touch.

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Pacinian corpuscles

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Deep-pressure and vibration receptors located in the deep dermis or hypodermis.

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Arrector pili

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Small smooth muscle attached to hair follicles; stands hair erect during cold or emotional responses.

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Sebaceous glands

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Oil-producing glands that secrete sebum to lubricate hair and skin and inhibit bacterial growth.

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Eccrine sweat glands

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Widely distributed glands that secrete a watery sweat onto the skin surface to cool the body through evaporation.

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Apocrine sweat glands

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Larger glands in the armpits and genital region that secrete a sweat-lipid mixture into hair follicles; active after puberty.

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Hair follicle

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Structure that houses the hair, with the hair bulb and hair matrix generating keratinocytes that form the hair shaft.

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Lunula

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Pale crescent at the base of the visible nail body indicating growth zone of the nail.