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Dermis Anatomy and Physiology Overview

Anticipated Problems

  • Characteristics of the dermal-epidermal junction, papillary layer, and reticular layer.
  • Functions of the dermis.
  • Dermis growth and repair mechanisms.

Key Terms

  • Arrector pili muscles: Tiny muscles attached to hair follicles.
  • Collagen fibers: Provide toughness to the dermis.
  • Dermal-epidermal junction: Area of contact between epidermis and dermis.
  • Elastic fibers: Allow stretchability of the dermis.
  • Fibroblasts: Cells that form connective tissue.
  • Krause’s end bulbs, Meissner’s corpuscles, Pacinian corpuscles, Ruffini’s corpuscles: Types of sensory receptors.
  • Papillae: Projections in the papillary layer.
  • Sebaceous glands: Oil-producing glands for skin lubrication.
  • Sweat glands: Secrete perspiration for cooling.
  • Reticular layer: Dense network of fibers in the dermis.

Dermal-Epidermal Junction

  • Consists of a basement membrane, specialized fibers, and polysaccharide gel.

Papillary Layer

  • Composed of bumps called papillae that project into the epidermis.

Reticular Layer

  • Contains a dense network of interlacing fibers, tough collagen, and elastic fibers that allow stretching.

Skin Adnexa

  • Include hair follicles, arrector pili muscle, sebaceous glands, sweat glands, nails, and Pacinian corpuscles.

Functions of Dermis

  • Provides mechanical strength and protects against injury.
  • Acts as a storage area for water and electrolytes.
  • Contains nerve receptors for pain, pressure, touch, and temperature.
Sensory Receptors in Dermis
  • Nociceptors: Respond to pain.
  • Meissner’s corpuscles: Light touch in hairless areas.
  • Ruffini’s corpuscles: Deep pressure and continuous touch.
  • Pacinian corpuscles: Rapid response to deep pressure.

Regulation of Body Temperature

  • Achieved through blood vessel dilation/constriction, sweat glands, hair follicles, and muscle fibers.

Growth and Repair

  • The dermis retains cells but does not continually regenerate like the epidermis.
  • Fibroblasts form a dense mass during wound healing; if not replaced, it may become a scar.
  • Langer’s lines: Orientation of collagen fibers determines scar appearance.
  • Elastic fibers may tear, resulting in stretch marks that evolve into scar lines.

Review Questions

  1. Name two structures in the dermis that help maintain body temperature.
  2. Identify two types of sensory receptors found in the dermis.
  3. What three elements assist the dermis in regulating body temperature?