Skin Anatomy and Melanin (Chapters 1–7)

Vocabulary flashcards covering the skin's structure (epidermis, dermis, hypodermis), cell types, skin layers, glands, pigments, and related concepts mentioned in Chapters 1–7.

Epidermis

Outer, avascular layer of skin made of keratinized stratified squamous epithelium; four layers in thin skin, five layers in thick skin; contains keratinocytes, melanocytes, Langerhans cells, and Merkel cells.

Dermis

Deep, fibrous connective tissue layer beneath the epidermis; supports epidermis and houses blood vessels, nerves, hair follicles, sweat and sebaceous glands; two sublayers: papillary and reticular.

Hypodermis (Subcutaneous Layer)

Not a true skin layer; mainly adipose and areolar connective tissue; anchors skin to underlying tissue and stores most body fat.

Papillary Dermis

Superficial dermal layer of areolar connective tissue; contains capillaries and nerve endings; forms dermal papillae that interface with the epidermis.

Reticular Dermis

Deeper dermal layer of dense irregular connective tissue; rich in collagen and elastic fibers; houses hair follicles, glands, and nerves.

Keratinocytes

Most abundant epidermal cells that produce keratin to form a tough, water-repellent barrier.

Melanocytes

Pigment-producing cells in the deepest epidermal layer; synthesize melanin and transfer it to keratinocytes to determine skin color and UV protection.

Langerhans Cells

Dendritic immune cells in the epidermis (stratum spinosum) that present antigens to the immune system.

Merkel Cells

Touch-receptive cells in the deepest epidermal layer; associated with nerve endings for light touch.

Stratum Basale

Bottom epidermal layer; single cell layer, site of cell division; contains stem cells, melanocytes, and Merkel cells.

Stratum Spinosum

Several layers of keratinocytes above the basale; contains Langerhans cells; appeared spiny under microscope.

Stratum Granulosum

Granular layer where keratinocytes begin keratinization and lose their nuclei; transitional layer before dying cells.

Stratum Lucidum

Clear layer present only in thick skin; lies between granulosum and corneum.

Stratum Corneum

Outermost layer of dead, keratin-filled cells; provides waterproof, protective barrier.

Thick Skin

Skin on palms and soles with five epidermal layers (including lucidum) and a thicker stratum corneum.

Erector Pili

Smooth muscle attached to hair follicles; contracts to produce goosebumps.

Hair Follicle

Structure that produces hair; contains rapidly dividing cells in the bulb and associates with sebaceous glands.

Sebaceous Gland

Gland that secretes sebum into the hair shaft and surface of the skin, lubricating hair and skin; often active at puberty.

Sebum

Oily secretion that lubricates hair and skin; contributes to oiliness and acne when overproduced or infected.

Sweat Glands

Glands that produce sweat for thermoregulation and excretion; distributed throughout the dermis.

Melanin

Pigment produced by melanocytes; determines skin color and absorbs UV radiation to protect DNA.

Carotene

Orange-yellow pigment from diet; accumulates in the stratum corneum and dermis to influence skin tint.

Hemoglobin

Oxygen-carrying pigment in blood; affects skin color (red/pink); cyanosis indicates low oxygen saturation.

Tan

Epidermal darkening due to UV-induced increased melanin; fades as epidermal turnover replaces pigmented keratinocytes.

Tattoo

Pigment deposited in the dermis; typically long-lasting because the dermis is not sloughed off like the epidermis.

Decubitus Ulcers

Pressure ulcers from prolonged compression that cuts off blood flow to the dermis.

Striae

Stretch marks from dermal tearing due to rapid skin stretching; common with growth, pregnancy, or weight gain.

Vitamin D Production

UV exposure stimulates skin to synthesize vitamin D, important for calcium metabolism.