Milady Standard Esthetics Chapter 3

Skin Glands and Functions

• Apocrine Glands: Coiled structures in the underarm and genital areas that secrete sweat connected to hair follicles.
• Eccrine Glands: Sweat glands located all over the body, opening onto the skin's surface through pores; do not produce offensive odor.
• Sebaceous Glands: Appendages connected to hair follicles, secreting sebum to lubricate skin and hair.

Skin Structure and Composition

• Epidermis: Outermost layer of the skin consisting of several layers, including the stratum corneum and stratum germinativum.
• Dermis: Considered the "true skin" with two main layers: papillary (top layer) and reticular (deeper layer) providing nourishment and strength.
• Subcutaneous Layer: Also known as hypodermis/adipose tissue, acts as insulation and energy storage beneath the dermis.

Cellular Elements

• Keratinocytes: Main cells in the epidermis, primarily composed of keratin, playing key roles in skin barrier function.
• Melanocytes: Cells that produce melanin, which determines skin, hair, and eye color, offering protection against UV radiation.
• Fibroblasts: Cells that stimulate collagen and elastin production, crucial for skin firmness and elasticity.

Key Proteins and Compounds

• Collagen: Protein in the dermis providing firmness; topically binds water and has various sources, including animal placentas.
• Elastin: Fibrous protein that helps skin maintain elasticity.
• Ceramides: Glycolipid materials that contribute to the skin’s barrier and hydration.

Skin Conditions

• Couperose: Condition characterized by damaged capillaries, leading to redness and visible blood vessels.
• Rosacea: Chronic skin condition marked by flushing, visible blood vessels, and in some cases, papules and pustules.

Melanin Types

• Eumelanin: Dark brown to black pigment found predominantly in individuals with darker skin.
• Pheomelanin: Red and yellow pigment prevalent in individuals with lighter skin tones.

Skin Functions

• Barrier Function: The epidermis acts as a protective barrier against irritation and dehydration; it includes structures like desmosomes and the intercellular matrix.
• Hydrolipidic Balance: Maintains the oil-water balance that protects the skin's surface.
• Transepidermal Water Loss (TEWL): Refers to water loss due to evaporation, affecting skin hydration.

Immune Response

• Langerhans Cells: Immune cells in the epidermis that identify foreign invaders and facilitate their removal through the lymph system.
• Leukocytes: White blood cells that help fight infection by digesting harmful bacteria and responding to allergies.

UV Radiation

• UVA Radiation: Longer wavelengths (320-400 nm) that penetrate deeply, contributing to skin aging and genetic damage.
• UVB Radiation: Shorter wavelengths (290-320 nm) that cause skin burning and contribute significantly to skin cancer risk.

Membranes and Lipid Layers

• Bilayers: Thin membranes formed of two layers of lipid molecules, crucial for cell integrity and communication.
• Intercellular Matrix: Lipid substances filling spaces between cells to prevent water loss.

Skin Layers Overview

• Stratum Corneum: Outermost protective layer, containing dead cells.
• Stratum Lucidum: Clear layer found primarily on palms and soles; thick and protective.
• Stratum Granulosum: Layer where cells begin to keratinize; responsible for replacing shed cells.
• Stratum Spinosum: Contains desmosomes for cell connection; helps in skin strength.
• Stratum Germinativum: Active layer where cell mitosis occurs, producing new skin cells.

Additional Terms

• Dermal Papillae: Finger-like projections aiding in anchoring the epidermis, full of capillaries for nourishment.
• High-Energy Visible Light: Light from electronic devices, penetrating deeply and damaging collagen and elastin.
• Hyaluronic Acid: Water-binding agent that keeps skin hydrated.

These notes encapsulate essential terminology, their definitions, and the role of various skin components to support effective learning in esthetics.