Lecture Notes: Integumentary System

Unit Overview

• Today's Focus: First page of lab list: skin models.
• Next Classes: Axial and appendicular bones.
• Resources: Class handout and concept map are available in the front of the room and on D2L.
• Quiz 3: Based on the handout and concept map.

Class Handout & Concept Map

• Layers of the Integument System: Focus on different layers of the skin and their functions.
• **Five Key Functions of the Skin: **
  1. Protection:
     • From abrasions, dehydration, and bacterial growth.
     • Includes physical, chemical, and biological barriers.
  2. Thermoregulation:
     • Sweat production and blood flow regulation.
  3. Sensation:
     • Touch and pressure receptors.
  4. Metabolic Functions:
     • Vitamin D synthesis in response to sunlight.
     • Important for calcium absorption and bone health.
  5. Excretion:
     • Removal of waste through sweat.

Detailed Skin Structure

• Epidermis:

  • Five layers: Stratum Corneum, Lucidum, Granulosum, Spinosum, Basale.
  • Stratum Corneum: Outermost, dead cells, protection.
  • Stratum Lucidum: Only in thick skin (palms, soles).
  • Stratum Granulosum: Keratin formation, cells start to die.
  • Stratum Spinosum & Basale: Living cells, nutrients supplied.

• Dermis:

  • Papillary Layer: Areolar tissue, dermal ridges for fingerprints, increased surface area for attachment and nutrient diffusion.
  • Reticular Layer: Dense irregular tissue, hair roots, glands, nerve endings.

• Hypodermis:

  • Not part of the skin, adipose tissue, blood vessels.
  • Contains major blood vessels supplying the dermis.

Cell Types in the Epidermis

1. Keratinocytes: Most common, produce keratin.
2. Melanocytes: Produce melanin for UV protection.
3. Merkel (Tactile) Cells: Sensory touch receptors.
4. Langerhans (Dendritic) Cells: Immune response, capture invaders.

Accessory Structures

• Hair, Nails, Glands:
  • Sweat Glands (Sudoriferous):
    • Eccrine: Watery sweat, all over the body, temperature regulation.
    • Apocrine: Musky sweat, found in armpits/groin, pheromone release.
  • Sebaceous Glands: Oily, always associated with hair follicles.

Sensory Receptors

• Meissner Corpuscles: Light touch, found in dermal papillae.
• Pacinian Corpuscles: Deep pressure and vibration, found deeper in the dermis.

Hypodermis and Dermal Blood Supply

• Hypodermis:
  • Adipose tissue and arteries/veins.
  • Blood supply feeds upper dermis and epidermis layers.

Skin Pigmentation

• Pigments: Melanin, Carotene, Hemoglobin.
• Function of Melanin: Protects DNA from UV damage.

Types of Burns

1. First-Degree: Affects only epidermis.
2. Second-Degree: Extends into dermis.
3. Third-Degree: Extends through dermis into hypodermis.

Study Tips

• Quiz Preparation: Use class handout and concept map as study guides.
• Practice: Complete blank copies of handouts for exam preparation.

Note: Additional resources and keys for the handout available for reference.