Integumentary System

Introduction

• Comprises skin, hair, nails, and glands.
• Functions include protection, homeostasis, sensation, and thermoregulation.

Key Terms

• Integumentary System
• Epidermis
• Dermis
• Hypodermis
• Sebaceous Glands
• Sweat Glands
• Hair Follicle
• Nail Plate
• Keratin

Tips for Understanding

• Remember the three layers of the skin: epidermis, dermis, hypodermis.
• Link functions of skin components to their protective roles.
• Use comparisons to NYC structures to understand concepts.

The Three Main Layers of the Skin

1. Epidermis: Outermost layer, stratified squamous epithelium, waterproof barrier.
2. Dermis: Middle layer with connective tissue, blood vessels, nerves; provides strength and elasticity.
3. Hypodermis: Deepest layer, adipose tissue, insulates and cushions.

The Five Layers of the Epidermis

• Stratum Corneum: Dead keratinized cells, protection against pathogens and water loss.
• Stratum Lucidum: Thin layer in thick skin, additional cushioning.
• Stratum Granulosum: Keratohyalin granules, waterproofing.
• Stratum Spinosum: Keratinocytes and Langerhans cells, strength and flexibility.
• Stratum Basale: Basal cells and melanocytes, new skin cell generation.

Hair and Nails: Parts and Functions

Hair

• Structure:
  • Hair Shaft: Visible, dead keratinized cells.
  • Hair Root: Below surface, in follicle.
  • Hair Follicle: Sheath for hair production.
  • Hair Bulb: Matrix for hair production.
  • Arrector Pili Muscle: Causes hair to stand in response to cold/stimuli.
  • Sebaceous Glands: Secrete sebum for lubrication.
• Functions:
  • Protection: UV and foreign particles shield.
  • Sensation: Enhances touch.
  • Thermoregulation: Retains heat via goosebumps.

Nails

• Structure:
  • Nail Plate: Hard, visible, keratinized.
  • Nail Bed: Beneath nail plate, nutrients and color.
  • Nail Root: Base under skin.
  • Cuticle: Protects skin-nail area.
  • Lunula: White crescent at base.
  • Nail Matrix: Growth tissue.
• Functions:
  • Protection: Fingertip safeguarding.
  • Tool Use: Aids in object manipulation and scratching.
  • Sensory: Enhances touch sensitivity.

Comparisons to NYC

• Hair Follicles: Like underground tunnels, with roots as subway cars.
• Arrector Pili: Emergency response team, trapping heat like NYC systems.
• Nails: Protective shields, akin to skyscrapers for fingertip tasks.

Review Questions

1. Outermost skin layer: c) Epidermis
2. Function of sebaceous glands: b) Secrete oil for lubrication
3. Layer for new skin cell production: c) Stratum Basale
4. Arrector pili function: b) Causes hair to stand up
5. Stratum corneum function: b) Waterproof barrier
6. Structure involved in hair growth: a) Hair bulb
7. Location of sweat glands: c) Dermis
8. Protein in nails: c) Keratin