week 4 lab objectives pt. 2- integumentary system

Epidermis

The outermost, avascular layer of the skin composed of keratinized stratified squamous epithelium.

Dermis

The thick inner layer of skin beneath the epidermis, containing blood vessels, nerves, and glands.

Hypodermis (Subcutaneous Layer)

The layer below the dermis, composed mostly of adipose tissue that anchors skin to underlying muscle.

Stratum Basale

The deepest epidermal layer containing stem cells, melanocytes, and Merkel cells, where active mitosis occurs.

Stratum Spinosum

The epidermal layer several cells thick containing spiny keratinocytes and Langerhans (dendritic) cells.

Stratum Granulosum

The epidermal layer where keratinocytes flatten, accumulate keratohyalin granules, and begin to die.

Stratum Lucidum

A clear, thin epidermal layer found only in thick skin like palms and soles.

Stratum Corneum

The most superficial epidermal layer, consisting of dead, flat, keratinized cells that constantly shed.

Papillary Layer

The superficial layer of dermis containing dermal papillae, capillary loops, and Meissner corpuscles.

Reticular Layer

The deep, thick dermis layer composed of dense irregular connective tissue, collagen, and elastic fibers.

Melanocytes

Cells in the stratum basale that produce melanin to protect skin from ultraviolet radiation.

Keratinocytes

The primary cell type of the epidermis that produces the protective protein keratin.

Sebaceous Glands

Exocrine glands that produce sebum, an oily secretion that lubricates skin and hair.

Eccrine Sweat Glands

Abundant tubular glands that produce watery sweat for thermoregulation all over the body.

Apocrine Sweat Glands

Glands located in axillary and anogenital areas that produce a viscous sweat associated with body odor.

Nail Body (Plate)

The visible, hard portion of the nail covering the nail bed.

Nail Bed

The deeper layer of epidermal epithelium beneath the nail body.

Nail Root

The proximal part of the nail embedded under the skin surface.

Nail Matrix

The actively growing region at the proximal end of the nail responsible for nail growth.

Eponychium (Cuticle)

The fold of stratum corneum over the proximal edge of the nail body.

Lunula

The crescent-shaped white area at the base of the nail plate.

Hyponychium

The region beneath the free edge of the nail that secures the nail to the fingertip.

Arrector Pili Muscle

Smooth muscle attached to hair follicles that contracts to pull hair upright (goosebumps).

Tactile/ Meissner corpuscle

Within the papillary layer of the dermis capable of detecting light touch and or tickles

Lamellar corpuscle

Within the reticular layer of the dermis- capable of detecting pressure

Hair root

The part of the hair contained within the follicle, below the surface of the scalp.

Hair bulb

The rounded, club-shaped part of hair located at the end of the hair root

Hair follicle

The tube-like depression or pocket in the skin or scalp that contains the hair root.

Hair shaft

The portion of hair that projects above the epidermis