Lecture on the Integumentary System

Introduction

• Focus: Integumentary system, the largest organ (skin)
• Importance of the skin:
  • Maintains homeostasis
  • Regulates internal body temperature and fluid balance
  • Protects against physical damage and pathogens
  • Site of vitamin D synthesis
  • Sensory functions

Structure of the Skin

• Epidermis: Outermost layer
  • Keratinocytes: Produce keratin, enhancing water resistance and toughness
  • Layer sequence mnemonic: "Come Let's Get Sunburned"
    • Stratum Corneum: Dead, cornified cells
    • Stratum Lucidium: Thick skin areas (soles, palms)
    • Stratum Granulosum: Keratinocytes flatten, accumulate granules
    • Stratum Spinosum: Contains keratinocytes and Langerhan cells
    • Stratum Basile: Mitosis of keratinocytes, contains melanocytes and Merkel cells
• Dermis: Middle layer
  • Contains blood vessels, connective tissue, sweat glands, nerves, hair follicles
  • Proteins: Collagen (structural support), Elastin (elasticity)
  • Sub-layers:
    • Papillary Layer: Loose connective tissue
    • Reticular Layer: Dense connective tissue
  • Scar formation and keloids
• Hypodermis: Subcutaneous tissue layer
  • Connects skin to underlying bone/muscle
  • Composed of adipose tissue (stored fat)

Accessory Structures

• Sweat Glands: Regulate body temperature through perspiration
• Sebaceous Glands: Produce oil for waterproofing and lubrication
• Hair Follicles: Cell mitosis drives hair growth
• Nails: Originate from the epidermis, protect fingertips and toes

Medical Conditions

• Skin Cancer
  • Most common cancer in the US
  • Types:
    • Basal cell carcinoma: From basal cells
    • Melanoma: From melanocytes
    • Squamous cell carcinoma: From squamous cells
  • Caused by UV radiation exposure
• Burns
  • Classified by depth:
    • First Degree: Epidermis
    • Second Degree: Epidermis + upper dermis
    • Third Degree: Epidermis + dermis
    • Fourth Degree: Deep tissue, muscle, bone
  • Major risks: Fluid retention, infection

Conclusion

• Importance of understanding the integumentary system for the ATITs exam
• Additional resources available at nurse store.com