LAB SKIN

Integument Overview

• The integumentary system covers the body and consists of skin and accessory tissues such as nails, hair, sweat glands, and sebaceous glands.

• The inguinal system is synonymous with skin and often termed cutaneous membrane.

• It serves as a barrier to the outside world and is a visual indicator of physiology and health.

• Dermatology is the study of skin.

Composition and Functions of the Integument

Layers of the Integument

• Epidermis: Outermost layer made of stratified squamous epithelium.

• Dermis: Deeper layer consisting primarily of dense irregular connective tissue.

• Subcutaneous Layer (Hypodermis): Composed of alveolar and connective tissue; it is not considered part of the integumentary system.

Visual Breakdown of Integument Layers

• Figure 6.1 illustrates the layers of integument:

  • Epidermis

  • Dermis

  • Subcutaneous Layer

  • Other components include hair follicles, sensory receptors, sweat glands, sebaceous glands, and connective tissue types.

• Papillary Layer: Superficial layer of the dermis.

• Reticular Layer: Deeper layer of the dermis that provides strength and elasticity.

Epidermis Details

Epithelium of the Integument

• The epidermis is a keratinized, stratified squamous epithelium.

• Composed of layers (strata) from deep to superficial:

  • Stratum Basale: Deepest layer; responsible for generating new keratinocytes.

  • Stratum Spinosum: Provides strength and flexibility to the skin.

  • Stratum Granulosum: Contains keratinocytes transitioning to a more hardened state.

  • Stratum Lucidum: Present only in thick skin, provides an additional layer.

  • Stratum Corneum: Outermost layer; consists of dead keratinocytes protecting underlying layers.

Variations in the Epidermis

• Thickness: Varies between thick and thin skin.

  • Thick Skin: Found in the palms of the hands and soles of feet; contains all five layers and sweat glands but lacks hair follicles and sebaceous glands.

  • Thin Skin: Covers most of the body; lacks stratum lucidum but has sweat glands, hair follicles, and sebaceous glands.

Visual Comparison of Thick Skin vs. Thin Skin

• Figure 6.3 shows comparison:

  • (a) Thick skin - Contains all five epidermal strata.

  • (b) Thin skin - Lacks stratum lucidum and varies in the number of other structures.