A&P1 Chapter 5-Integumentary system

Functions of the skin

Protection, temperature regulation, sensation, prevention of water loss, and vitamin D synthesis.

Keratinocytes

Produce keratin, which strengthens and waterproofs the epidermis.

Melanocytes

Produce melanin, which contributes to skin color and protects against UV radiation.

Dendritic (Langerhans) cells

Immune cells that detect and present antigens.

Tactile (Merkel) cells

Help detect light touch.

Epidermis

Outermost, avascular layer of the skin made of keratinized stratified squamous epithelium.

Dermis

Vascular connective tissue containing blood vessels, nerves, glands, and hair follicles.

Hypodermis

Subcutaneous tissue rich in fat and loose connective tissue; cushions, insulates, and anchors skin.

Stratum basale

Deepest epidermal layer; produces new keratinocytes.

Stratum spinosum

Provides strength and flexibility; contains keratinocytes and immune cells.

Stratum granulosum

Cells accumulate keratin-related materials and begin to die.

Stratum lucidum

Extra epidermal layer found only in thick skin, such as palms and soles.

Stratum corneum

Outermost layer of dead, flattened, keratin-filled cells.

Epidermal layers, deep to superficial

Basale, spinosum, granulosum, lucidum, corneum.

Papillary layer

Superficial dermis made of areolar connective tissue; contains dermal papillae and capillaries.

Reticular layer

Deeper dermis made of dense irregular connective tissue; provides strength and elasticity.

Dermal ridges

Create fingerprints and increase attachment between dermis and epidermis.

Cleavage lines

Follow collagen fiber orientation in the dermis; cuts parallel to them often heal better.

Flexure lines

Skin creases where skin folds over joints.

Melanin

Skin pigment produced by melanocytes; helps protect against UV radiation.

Carotene

Yellow-orange pigment that can accumulate in skin and fat.

Hemoglobin

Blood pigment that contributes pink or reddish skin tones.

Cyanosis

Bluish skin associated with reduced oxygenation of blood.

Pallor

Unusual skin paleness, often related to reduced blood flow or anemia.

Erythema

Skin redness caused by increased blood flow, often from inflammation.

Jaundice

Yellowing of skin and eyes caused by bilirubin buildup.

Bruise

Discoloration caused by blood leaking into tissues and breaking down.

Skin cancer

Abnormal growth of skin cells; major types include basal cell carcinoma, squamous cell carcinoma, and melanoma.

Burn classification

First-degree affects epidermis; second-degree affects epidermis and part of dermis; third-degree destroys the full thickness of skin.

Rule of Nines

A method for estimating the percentage of adult body surface area affected by burns.

Functions of hair

Protection, light-touch sensation, and helping reduce heat loss.

Hair tissue type

Hair is made of dead, keratinized epithelial cells.

Hair shaft

The portion of hair extending above the skin surface.

Hair medulla

Innermost layer of the hair shaft.

Hair cortex

Middle layer of the hair shaft; provides strength and contains pigment.

Hair cuticle

Outer protective layer of the hair shaft.

Hair root

Part of the hair below the skin surface.

Hair bulb

Expanded base of the hair root where growth occurs.

Hair follicle

Tube-like structure in the skin that surrounds and anchors the hair root.

Hair matrix

Dividing cells in the hair bulb that produce hair.

Hair color

Determined mainly by the type and amount of melanin in hair.

Lanugo hair

Fine hair that covers the fetus.

Vellus hair

Fine, short, lightly pigmented body hair.

Terminal hair

Coarser, longer, often more pigmented hair, such as scalp hair.

Hair thinning and baldness

Can result from genetics, hormones, aging, illness, or other factors.

Free edge of nail

The part of the nail plate extending beyond the fingertip.

Nail plate

The hard, visible keratin structure commonly called the nail.

Nail root

The proximal part of the nail hidden beneath the skin.

Nail bed

Skin beneath the nail plate.

Nail matrix

Growth region that produces new nail cells.

Merocrine (eccrine) sweat glands

Release watery sweat onto the skin surface for cooling.

Apocrine sweat glands

Release thicker secretions into hair follicles, especially in the armpits and groin.

Sebaceous glands

Secrete sebum, an oily substance that lubricates skin and hair.