Milady Esthetics Ch. 3 Physiology and Histology of the Skin

Vocabulary flashcards covering the key terms, skin layers, structures, and cellular functions from Milady Esthetics Chapter 3: Physiology and Histology of the Skin.

Physiology

The study of functions and activities performed by body structures, including physical and chemical processes.

Histology

Also known as microscopic anatomy; the study of the structure and composition of tissue.

Skin Physiology and Histology

The study of the structure and composition of the skin tissue.

Integumentary System

The skin and its appendages, which acts as the largest organ in the body and a strong protective barrier.

Appendages of the Skin

Structures produced by or associated with the skin, including hair, nails, sweat glands, and oil glands.

Acid Mantle

A protective barrier made up of sebum, lipids, sweat, and water with an average pH of $5.5$.

Hydrolipidic Film

An oil-water balance film on the skin surface that protects it from drying out and exposure to external damaging factors.

Barrier Function

The skin's mechanism that protects from irritation and intercellular transepidermal water loss.

Transepidermal Water Loss (TEWL)

Water loss caused by evaporation on the skin's surface.

Intercellular Matrix

Protective lipid cement mortar located between epidermal cells that holds them together.

Melanocytes

Cells that produce skin pigment to protect against UV rays and determine skin color.

Melanosomes

Pigment granules that produce a protein called melanin.

Dendrites

Finger-like projections through which melanin travels from the deeper basal cell layer of the stratum germinativum to the skin surface.

Epidermal Growth Factor (EGF)

A factor that stimulates cells to reproduce and heal.

Fibroblasts

Cell stimulators that produce proteins and aid in the production of collagen and elastin.

Thermoregulation

The body's process of maintaining an internal average thermostat of $98.6^\text{o}\text{F}$ ($37^\text{o}\text{C}$) through evaporation, perspiration, radiation, and insulation.

Arrector Pili Muscles

Muscles attached to hair follicles that contract when cold, causing goosebumps.

Sudoriferous Glands

Sweat glands that excrete perspiration to assist in cooling the body and maintaining thermoregulation.

Sebum

An oily substance that lubricates and protects the surface of the skin and hair.

Sebaceous Glands

Oil glands attached to hair follicles that produce sebum.

Subcutaneous Layer

Also known as hypodermis or superficial fascia; the deepest layer composed of subcutis tissue and $80\%$ fat.

Subcutis Tissue

Also known as adipose tissue; creates a protective cushion that gives contour and smoothness to the body and serves as an energy source.

Dermis

Also known as corium cutis or true skin; a support layer of connective tissue located above the hypodermis that is $25$ times thicker than the epidermis.

Reticular Layer

The denser and deeper layer of the dermis comprised mainly of collagen and elastin.

Papillary Layer

The top layer of the dermis that connects to the epidermis, comprising $10\%$ to $20\%$ of the dermis.

Dermal Papillae

Membranes of ridges and grooves that attach the dermis to the epidermis.

Hair Papillae

Small, cone-shaped structures located at the bottom of hair follicles that supply nourishment.

Collagen

A complex protein fiber substance that makes up $70\%$ of the dermis, giving skin its strength and aiding in wound healing.

Elastin

Fibrous protein that forms elastic tissue and gives skin its elasticity.

Glycosaminoglycans (GAGs)

Large protein-sugar polysaccharide complexes found between dermal fibers that maintain protein fiber balance and retain moisture.

Hyaluronic Acid

A beneficial hydrating fluid and glycosaminoglycan (GAG) in the dermal matrix.

Lymphocytes

Infection-fighting cells found within the dermis.

Langerhans Cells

Guard cells found in the dermis that protect the immune system.

Mast Cells

Cells located in the dermis that are involved in allergic reactions.

Leukocytes

White blood cells found in the dermis that fight infections.

Dermal/Epidermal Junction

The connection between the dermis and epidermis consisting of layers of collagen tissue with small pockets and holes.

Onyx

The technical name for a nail.

Epidermis

The outermost layer of the skin composed of epithelial tissue, divided into five layers.

Stratum Germinativum

Also known as the germination, growth, or basal cell layer; the bottom layer of the epidermis.

Stratum Spinosum

Also known as the spiny cells layer of the epidermis.

Stratum Granulosum

Also known as the grainy cells layer of the epidermis.

Stratum Lucidum

Also known as the clear cells layer; present only where skin is thick, on the soles of feet and palms of hands.

Stratum Corneum

Also known as the horny cells layer; the outer layer of the epidermis.

Keratinocytes

Cells composed of keratin that comprise $95\%$ of the epidermis.

Keratin

A fibrous protein providing resiliency and protection, found in all layers of the epidermis.

Pores

Tubelike openings for sweat glands on the surface of the epidermis.

Follicles

Tubelike depressions in the skin with oil glands attached to them.