Physiology and Histology of the Skin - Chapter 3

Introduction

• Focus on physiology and histology of the skin from the Milady's Esthetician book (Page 83).
• Emphasis on why understanding these areas improves esthetician skills.

Importance of Skin Physiology and Histology

• Study involves anatomy, layers, and functions of the skin.
• Physiology: Study of body functions and activities including physical and chemical processes.
• Histology: Microscopic anatomy, structure, and composition of tissues.
• Estheticians as skin health specialists are sometimes called technicians, skin therapists, or specialists.
• Commitment to lifelong learning due to evolving scientific research and technologies.
• Understanding of other body systems' interaction with the integumentary system.

Attributes of Healthy Skin

• Skin (Integumentary system): Largest organ, protective barrier.
• Functions: Sensation, protection, heat regulation, excretion, secretion, absorption.
• Components: Skin layers, nerves, cellular functions, hair follicles, glands.
• Proteins (amino acids, peptides) are building blocks for maintaining skin health.

Six Primary Functions of the Skin

1. Sensation
   • Nerve sensors detect heat, cold, touch, pain, and pressure.
   • Sensory nerve fibers are abundant in fingertips.
2. Protection
   • Thin, strong barrier with defense mechanisms including sebum and acid mantle.
   • Hydro-lipidic film protects from drying and damage.
   • Acid mantle pH is around 5.5.
3. Heat Regulation
   • Maintained at 98.6°F through evaporation, perspiration, radiation, insulation.
   • Sweat glands and blood flow aid in temperature regulation.
4. Excretion
   • Sudoriferous glands (sweat glands) excrete perspiration, minimal detoxification.
5. Secretion
   • Sebum lubricates skin and hair, helps retain water in cells.
   • Emotional stress, hormone imbalances affect sebum flow.
6. Absorption
   • Limited absorption of chemicals, hormones, moisture, oxygen.
   • Vitamin D synthesis, selective absorption of products based on molecular size.

Skin Layers and Their Functions

• Hypodermis (Subcutaneous Tissue)
  • Composed of loose connective and adipose tissue; 80% fat.
  • Provides energy, cushioning, and contour.
• Dermis
  • Composed of connective tissue with collagen and elastin.
  • Two layers: Reticular and papillary.
  • Contains blood vessels, nerves, fibroblast cells.
• Dermal-Epidermal Junction
  • Connects dermis to epidermis, providing strength and adhesion.

Epidermis Layers

1. Stratum Germinativum (Basal Layer)
   • Single layer, cell division (mitosis), stem cells and melanocytes.
2. Stratum Spinosum (Spiny Layer)
   • Cell division, creating protein bonds and strengthening epidermis.
3. Stratum Granulosum (Granular Layer)
   • Keratin production, forms waterproofing barrier.
4. Stratum Lucidum (Clear Layer)
   • Found in palms and soles, allows light passage.
5. Stratum Corneum (Horny Layer)
   • Top layer, keratinized cells, detoxification, and cell turnover.

Skin Color and Melanin

• Melanin: Pigment for sun protection.
• Two types: Pheomelanin (red/yellow) and Eumelanin (dark brown/black).
• Tyrosinase: Enzyme stimulating melanin production.
• Brightening agents: Tyrosinase inhibitors for reducing hyperpigmentation.

Conclusion

• Understanding skin physiology and histology is crucial for estheticians.
• Continuous learning and application of knowledge enhance care and treatment.