Chapter 3: Physiology and Histology of the Skin

Key Skin Layers

• Dermis:
  • Reticular Layer: Dense part of the dermis.
  • Papillary Layer: Upper layer of dermis.
• Epidermis:
  • Stratum Germinativum
  • Stratum Spinosum
  • Stratum Granulosum
  • Stratum Lucidum
  • Stratum Corneum

Appendages of the Skin

Hair

• Hair is an appendage of the skin, slender outgrowth.
• Important for treatments like body waxing and brow shaping.
• Hair follicle structure depicted in Figure 3-1.
• Hair growth rate: 0.5 inches/month, slows with age.
• Types of Keratin:
  • Alpha (A) Keratin: Softer.
  • Beta (B) Keratin: Harder, 90% in hair.
• Hair contains melanin influencing color.
• Concerns: Ingrown hairs, folliculitis.

Nails

• Hard translucent plates protecting fingers and toes.
• Composed of hard keratin (Onyx).
• Grow faster in summer, 1/10 to 1/8 inches monthly.
• Potential indicators of health issues, e.g., cyanosis.

Nerve Functions

• Types: Motor (efferent) and Sensory (afferent).
• Motor Nerves: Convey impulses to muscles/glands.
• Sensory Nerves: Send messages to the central nervous system.

Glands of the Skin

Sebaceous (Oil) Glands

• Secrete oil, connected to hair follicles.
• Larger on face and scalp.

Sudoriferous (Sweat) Glands

• Regulate temperature and excrete waste.
• Types:
  • Apocrine: In armpits, genital areas, connect to oil glands.
  • Eccrine: All over the body, active with high temperature/activity.

Factors Influencing Skin Health

• Essential Needs: Nourishment, protection, respiration, circulation.
• Influences: Heredity, sun exposure, habits, nutrition, lifestyle.

Immune System and Skin

• Key Cells:
  • Langerhans Cells: Process antigens.
  • Leukocytes: White blood cells, fight infections.
  • T Cells: Attack virus-infected cells, mature in thymus gland.

Skin Nourishment

• Blood and lymph nourish and maintain skin health.
• Lipids in the skin protect and hydrate cells.

Skin Aging and Damage

Sun Damage

• UV radiation (UVA, UVB, UVC) causes aging.
• UVA: Aging ray, penetrates deeper.
• UVB: Burning ray, less deep but more damaging.

Free Radicals

• Unstable molecules causing cellular damage.
• Antioxidants neutralize free radicals.

Environmental and Lifestyle Factors

• Pollutants, poor diet, and smoking/drinking accelerate aging.
• Hormones significantly influence skin's health and appearance.
• Glycation deteriorates collagen leading to wrinkles.

Hormones and Skin

• Estrogen crucial for skin health, anti-inflammatory.
• Hormonal balance affects skin elasticity and moisture.

Microcirculation

• Issues include couperose skin, rosacea.
• Hormonal changes impact blood circulation in skin.

Hormone Replacement Therapy (HRT)

• Used to balance estrogen; caution advised due to cancer links.

Conclusion

• Regular care and understanding of skin physiology vital for health.
• Glossary and flashcards recommended for study.

Additional Tips

• Regular facials and exfoliation promote skin health.
• Adequate hydration and protection from the sun are crucial.