Integumentary System Overview

Integumentary System Overview

• The integumentary system consists of skin, nails, and hair, providing a barrier between the environment and internal tissues and organs.
• Skin is the largest organ in the body, responsible for various functions:
  • Absorption of nutrients
  • Regulation of internal body temperature
  • Elimination of waste

Skin Layers

• Epidermis: Outermost layer, providing a barrier between the body and the environment.
  • Composed of a stratified squamous epithelium with 4-5 layers:
  • Stratum Basale: Innermost layer, contains:
    • Stem Cells: Rapidly divide to produce keratinocytes.
    • Melanocytes: Produce melanin, the pigment that determines skin color and protects against UV damage.
    • Merkel Cells: Sensory neurons detecting light touch.
  • Stratum Spinosum: Contains keratinocytes and Langerhans cells, involved in immune response.
  • Stratum Granulosum: Keratinocytes become flattened, contain keratohyaline granules for keratin aggregation and lipid release for skin protection.
  • Stratum Lucidum (only in palms and soles): Thin layer aiding in protection.
  • Stratum Corneum: Outermost layer with 20-30 layers of dead keratinocytes (corneocytes) that form the skin's protective barrier.

Dermis

• The dermis lies beneath the epidermis and consists of connective tissue:
  • Contains sensory nerve receptors responding to touch and transmitting signals to the peripheral nervous system.
  • Houses sweat glands for thermoregulation and sebaceous glands for skin lubrication and protection.
  • Blood and lymphatic vessels supply the skin.

Hypodermis

• The hypodermis is the deepest layer, composed of fatty tissue that connects the skin to underlying muscles and provides insulation.

Cellular Components of the Skin

• Epidermal Cells:
  • Keratinocytes: Primary cells that produce keratin.
  • Melanocytes: Disperse melanin to surrounding keratinocytes, affecting skin tone.
  • Langerhans Cells: Part of the immune system, providing protection.
  • Merkel Cells: Act as sensory receptors.
• Dermis Cells:
  • Fibroblasts: Produce collagen, giving skin its strength and structure.

Sensory Receptors in the Skin

• Touch receptors located in the epidermis and dermis include:
  • Meissner's Corpuscles: Detect light touch; found in sensitive areas like fingertips and lips.
  • Merkel Cells: In the stratum basale, respond to light touch.
  • Lamellar Corpuscles: Detect pressure and vibration; found in deeper structures like mammary glands and joints.
  • Free Nerve Endings: Detect pain, temperature, itch, and tickle.

Conclusion

• The integumentary system plays a vital role in protection, sensation, and homeostasis, with complex interactions between its various layers and cells. Understanding the structure and function of the skin and its components is critical for recognizing its importance in overall health.