Milady Esthetics Chapter 3: Skin Layers

• Study Notes: Milady Esthetics Chapter 3

Skin Layers

• Epidermis: The outermost protective barrier of the skin.
• Stratum Corneum: Composed of dead keratinized cells, shields the body from environmental damage.
• Stratum Lucidum: Found only in palms and soles, providing extra protection in these areas.
• Stratum Granulosum: Characterized by a granular appearance, with cells full of keratin.
• Stratum Spinosum: Contains desmosomes, which provide strength to the skin.
• Stratum Germinativum (Basal): The site of cell division and melanocyte activity.
• Dermis: Layer includes collagen, elastin, nerves, and blood vessels.
• Papillary Layer: Located directly below the epidermis and houses dermal papillae.
• Reticular Layer: A dense connective tissue layer that provides structural strength and elasticity to the skin.
• Subcutaneous Layer: Composed of fatty tissue, which provides insulation, protection, and energy storage.

Cell Types

• Keratinocytes: The main cell type, responsible for producing keratin and providing protection.
• Melanocytes: Responsible for pigmentation through melanin production, protecting against UV damage.
• Langerhans Cells: Immune cells that provide defense against pathogens.
• Fibroblasts: Produce collagen and elastin fibers, providing structural support to the skin.

Skin Proteins

• Keratin: A tough, waterproof protein, is a major structural element of the skin.
• Collagen: Offers strength and support and makes up the most abundant protein in the skin.
• Elastin: Allows the skin to return to its original shape, providing elasticity.

Skin Glands

• Sebaceous Glands: Produce sebum to lubricate the skin and hair.
• Sudoriferous Glands: Sweat glands that regulate body temperature.
• Eccrine: Sweat glands for thermoregulation, widely distributed on the body.
• Apocrine: Sweat glands found in underarms/genital areas, respond to stress/emotion.

Skin Functions

• Protection: Acts as a physical/chemical barrier against pathogens and environmental hazards.
• Temperature Regulation: Achieved through sweat evaporation and vessel dilation/constriction.
• Sensation: Nerve receptors in the skin detect sensations like pain, touch, and pressure.
• Excretion: Sweat removes metabolic waste from the body.
• Secretion: Sebum secretion maintains hydration and acts as a protective barrier.
• Absorption: Limited absorption of topical products and vitamins through the skin.

Skin Physiology

• Barrier Function: Prevents dehydration and blocks irritants from penetrating the skin.
• Acid Mantle: Protective acidic film on the skin that inhibits bacterial growth.
• Desquamation: Natural shedding of dead skin cells.

UV Radiation

• UVA: Aging rays, penetrate deeply, cause long-term damage to the skin.
• UVB: Burning rays, superficial damage, cause sunburn.
• UVC: Shortest wavelength, absorbed by the ozone layer.

Important Terms

• Keratinization: Hardening of cells, forming a protective barrier on the skin.
• Melanin: Protects from UV damage and determines skin color.
• Hydrolipidic Film: Protective barrier on the skin's surface.

Focus Areas for Exam

• Skin structure and functions, including the epidermis/dermis layers.
• Cell types and their specific roles in skin health.
• Function and differences of collagen, elastin, and keratin.
• Types and roles of skin glands (sebaceous vs sudoriferous).
• Effects of UV radiation on skin health and protective measures.

Concise study notes on skin layers and cell types as per Milady Esthetics Chapter 3. Covers epidermis, dermis, subcutaneous layers, and various cell types, including keratinocytes and melanocytes. Focuses on structure and function.