chapter 5 (integument)

Integument

Includes the skin and its associated structures; functions in protection, temperature and hydration regulation, sensation, and Vitamin D synthesis.

Epidermis

A keratinized stratified squamous epithelium that is avascular.

Dermis

The layer beneath the epidermis, mostly made of dense irregular connective tissue; well vascularized and contains sweat glands, hair roots, sebaceous glands, and nerves.

Hypodermis

The layer beneath the skin.

Keratinocytes

The most numerous cells in the epidermis; contain keratin and are linked by desmosomes.

Melanocytes

Cells that make melanin pigment; their cell bodies are in the basal layer.

Dendritic cells (Langerhans cells)

Migratory macrophages involved in body defense.

Tactile (Merkel) cells

Cells involved in touch function and connected to a sensory nerve.

Stratum basale

The deepest epidermal layer; a single layer of cells that is the germinating layer and has lots of mitosis. Contains keratinocytes, Merkel cells, and melanocytes.

Stratum spinosum

The epidermal layer several cells tall that contains keratinocytes.

Stratum granulosum

A thin epidermal layer with dark-staining granules where cells are filling with keratin.

Stratum lucidum

A transparent layer of flat, dead cells found only in thick skin, such as the palms and soles.

Stratum corneum

A thick layer of flat, dead cells.

Papillary layer

The top ~20% of the dermis; mostly made of areolar connective tissue and contains tactile (Meissner's) corpuscles.

Reticular layer

The bottom 80% of the dermis; made of dense irregular connective tissue where collagen patterns create cleavage lines and dermal ridges.

Skin coloration

The color of the skin produced by three pigments: melanin, carotene, and hemoglobin.

Melanin

The darkest pigment, varying from brown to black; made by melanocytes and gives freckles and moles their color.

Carotene

A yellow/orange pigment found in the stratum corneum and hypodermis.

Hemoglobin

The reddish pigment of blood found in skin capillaries.

Cyanosis

Bluish skin due to low O₂.

Erythema

Redness from inflammation.

Jaundice

Yellow skin, often from liver issues.

Hematoma

A bruise consisting of subcutaneous clotted blood.

Hair

An integumentary structure that functions in insulation, protection, sensation, and social signals.

Vellus hair

Soft, baby-like body hair.

Terminal hair

Coarse hair found on areas such as the scalp and eyebrows.

Hair shaft

The part of the hair that projects from the skin.

Hair root

The part of the hair embedded in the follicle.

Hair bulb

The base of the hair.

Medulla

The central layer of hair containing big cells and air spaces.

Cortex

The hair layer made of multiple layers of cells that provide color to the hair.

Cuticle

The thin, shingle-like outer layer of hair cells.

Hair follicle

A bag that holds the hair root.

Root hair plexus

A follicle receptor made of a neuron that wraps around the hair follicle.

Epithelial root sheath

The internal layer of the hair follicle.

Connective tissue root sheath

The connective tissue layer surrounding the hair follicle.

Hair matrix

The mitotic growth zone at the top of the hair bulb's papilla.

Arrector pili muscle

A smooth muscle that raises the hair and squeezes sebum into the follicle.

Nails

Hard epidermal structures with lots of keratin that function in scratching and picking up small items.

Nail bed

The deep epidermis of the nail.

Nail matrix

The proximal end of the nail bed, marked by the lunula.

Lunula

The marking at the proximal end of the nail matrix.

Eponychium

The cuticle or fold of the nail.

Hyponychium

The space under the free edge of the nail.

Sweat glands

Glands that produce sweat.

Eccrine glands

Simple tubular sweat glands that secrete by merocrine style and are found all over the body, especially on the forehead, hands, and feet.

Merocrine secretion

A secretion style used by eccrine sweat glands.

Eccrine sweat

Sweat containing water, salts, antibodies, and acid.

Apocrine glands

Simple tubular glands found in the axillary and anogenital regions; turned on during puberty and secrete fatty and protein-rich sweat.

Apocrine sweat

Sweat that is fatty and protein-rich.

Sebaceous oil glands

Simple alveolar glands that secrete sebum using a holocrine style.

Sebum

The secretion of sebaceous glands; lubricates and helps fight microbes.

Holocrine secretion

A secretion style used by sebaceous oil glands.

Ceruminous glands

Simple tubular glands that make ear wax.

Ear wax

A secretion made by ceruminous glands that repels insects, catches debris, and lubricates the ear drum.

Thick skin

Skin found in areas such as the palms and soles that contains the stratum lucidum.

Cleavage lines

Patterns created by collagen in the reticular layer of the dermis.

Dermal ridges

Ridges created by collagen patterns in the reticular layer of the dermis.