Hair + Integumentary

Integumentary System Overview

  • The integumentary system includes the skin, hair, nails, and glands.

  • Protects the body from the external environment.

  • Consists of three primary layers:

    • Epidermis: Outer layer of skin.

    • Dermis: Beneath the epidermis, supports and nourishes it.

    • Hypodermis (Subcutaneous Layer): Not technically part of the integumentary system but connects the dermis to underlying structures.

Epidermis Layers

  • The epidermis consists of five layers, but the models may only show four.

  • Acronym to remember layers from superficial to deep: Calm, Bloods, and Sunburn.

    • Stratum Corneum: Most superficial layer, composed largely of keratinocytes.

    • Stratum Lucidum: Present only in thick skin (palms/soles), missing in models.

    • Stratum Granulosum: Cells begin keratinization, appears granulated.

    • Stratum Spinosum: Spiny projections on cells, contains Langerhans cells (immune cells).

    • Stratum Basale: Deepest layer where skin cells originate and divide through mitosis.

    • Melanocytes: Cells that produce melanin, contributing to skin pigmentation.

Histology of the Epidermis

  • Histology slides show cellular structure:

    • Stratified squamous epithelium in the epidermis (protective layer).

    • Basement membrane separates epidermis and dermis.

Dermis Structure

  • The dermis consists of two layers:

    1. Papillary Layer:

      • Contains sensory structures for touch (e.g., Meissner's corpuscles).

    2. Reticular Layer:

      • Dense irregular connective tissue, houses hair follicles, glands, and blood vessels.

      • Contains structures like hair follicles, sweat glands, and erector pili muscles.

Erector Pili Muscle

  • The erector pili muscle contracts causing hair to stand up when cold, creating goosebumps.

Glands in the Integumentary System

  • Sebaceous Glands: Connected to hair follicles; secrete oily substance to prevent infections, activated during puberty.

  • Sweat Glands:

    • Eccrine: Distributed throughout the body for cooling.

    • Apocrine: Found in specific areas (e.g., armpits), produces odor.

Hair Structure

  • Hair Bulb: Located in the dermis, contains the matrix producing hair cells.

  • Hair Root: Extends from the bulb up toward the surface.

  • Recognize hair structure models in practical assessments.

Practical Assessment Preparation

  • Review models for the identification of different skin layers, the dermis, and glands.

  • Familiarize with the characteristics of each layer and associated structures.

  • Be prepared to identify and differentiate between hair, glands, and their functions.