Lecture on the Dermis

Overview

• The dermis is primarily composed of strong, flexible connective tissue.
• Contains cellular elements like fibroblasts, macrophages, mast cells, and various white blood cells.
• Important for the maintenance and functionality of the dermis, including inflammatory response due to histamine in mast cells.
• Fibers in the connective tissue form a matrix connecting the dermis to the epidermis and hypodermis.
• Contains nerve fibers, blood vessels, lymphatic vessels, hair follicles, sweat glands, and sebaceous glands.

Layers of the Dermis

• The dermis is divided into two main layers:
  1. Papillary Layer
  2. Reticular Layer

Papillary Layer

• Located just below the stratum basale.
• Composed of areolar connective tissue with collagen and elastic fibers.
• Contains blood vessels.
• Features finger-like projections known as dermal papillae.
  • May contain capillary loops (related to thermal regulation).
  • Includes Meissner's corpuscles (touch receptors) sensitive to rapid, low-frequency signals.
  • Contains free nerve endings for pain reception.
• In thick skin (e.g., palms, fingertips), forms dermal ridges responsible for fingerprints.
  • Enhances gripping ability by increasing friction.
• Increases surface area for nutrient exchange between dermis and epidermis.

Reticular Layer

• Comprises about 80% of the dermis.
• Made of denser fibrous connective tissue compared to the papillary layer.
• Contains collagen that extends into the hypodermis and stratum basale to strengthen the skin.
  • Binds water, helping to keep the skin hydrated.
  • Aging results in loss of hydration.
• Contains elastic fibers allowing the skin to stretch.
• Collagen runs in parallel lines forming cleavage lines, which are significant for wound healing.
  • Incisions aligned with cleavage lines heal faster.
  • Important consideration for surgical procedures to minimize disruption of collagen fibers.