Integumentary System Overview

Components of the Integumentary System

• Skin
• Accessory Structures: Hair, nails, glands
  • Sweat glands
  • Oil glands
• Other Components: Blood vessels, muscles, nerves

Functions of the Integumentary System

• Maintains body's integrity
• Protective mechanism
• Regulates body temperature
  • Hair stands up in cold weather to save heat
  • Sweating in hot weather to release heat
• Activates Vitamin D in sunlight
• Provides sensory information
• Maintains homeostasis

Structure of the Skin

• Three Main Layers:
  1. Epidermis: Thin outer layer
  2. Dermis: Large middle layer
  3. Subcutaneous Layer (Hypodermis): Fat layer underneath

Types of Skin

• Thin Skin: Everywhere with hair, except palms and soles
• Thick Skin: Palms of hands and soles of feet

Cells in the Epidermis

1. Keratinocytes: Produce keratin, a protective fibrous protein
2. Melanocytes: Produce melanin, a pigment
3. Intradermal Macrophages: Immune system cells, phagocytose bacteria
4. Tactile Cells: Sensory cells

Layers of the Epidermis (from deepest to surface)

1. Stratum Basale
   • Highly mitotic cells
   • Cells replicate rapidly
   • Contains melanocytes
2. Stratum Spinosum
   • Cells begin to flatten
3. Stratum Granulosum
   • More flattened cells
4. Stratum Lucidum (only in thick skin)
5. Stratum Corneum
   • Flat, dead, keratin-filled cells

Pigmentation

• Melanocytes located in Stratum Basale
• Skin color determined by melanin production and uptake by keratinocytes
• Genetically controlled, multiple genes involved

Dermis

• Two Layers:
  1. Papillary Layer: Forms fingerprints
  2. Reticular Layer: Irregular connective tissue
• Connects epidermis to connective tissue

Hypodermis (Subcutaneous Layer)

• Connects epithelial tissues to underlying tissues

Additional Structures in the Skin

• Glands
• Blood vessels
• Hair follicles
• Papillary layer connects with dermis

Conclusion

The integumentary system comprises more than just skin and plays a critical role in protection, temperature regulation, vitamin D activation, and sensory reception, all contributing to maintaining homeostasis.