Skin and Epidermal Disorders Quiz

Skin Diseases with Defects in Cytoskeleton, Cellular Junctions and ECM

• Learning Outcomes:
  • Describe the structure and function of cytoskeleton molecules, cellular junctions, and ECM in maintaining skin integrity.
  • Explain the pathophysiological mechanisms underlying skin diseases.
  • Compare the clinical manifestations and disease progression of several skin diseases.
  • Evaluate current treatment and potential future therapies.

Skin, Cytoskeleton, Cellular Junction and ECM Review

• Skin Structure and Function
• Cytoskeleton Molecules
• Importance of Cellular Junctions
• Importance of Extracellular Matrix (ECM)

Skin Overview

• Protection: Protects the body from physical trauma and prevents water loss.

• Temperature Regulation: Helps regulate body temperature.

• Sensory Perception: Allows awareness of surroundings through sensory receptors.

• Chemical Synthesis: Synthesizes chemicals such as melanin and vitamin D.

• Parts of the Skin:

  • Epidermis: Outermost layer, waterproof barrier, creating skin tone
  • Dermis: Inner layer, thick, composed of loose fibrous connective tissue, contains blood vessels, sensory receptors, and glands.
    • Papillary Layer: Loosely arranged collagen fibers, creates fingerprint detail
    • Reticular Layer: Densely woven collagen and elastic fibers, cushions from stress and strain
    • Provides Strength, Elasticity, and Nutrients to Skin
    • Supports Body Temperature Regulation
    • Provides Sensation
  • Hypodermis: Anchoring skin to underlying structures, allowing flexibility and movement, fat and connective tissue, insulation and cushioning, energy storage

Skin: Epidermis

• Structure: Outermost layer, multiple sub-layers (corneum, granulosum, etc.)
• Function: Waterproof barrier, creating skin tone.
• Corneocytes: Cells forming the outermost layer.
• Intercellular Lipids: Maintaining waterproof barrier in stratum corneum
• Tight Junctions: Barrier function and prevents vaporization of water.

Skin: Newly Formed Epidermis

• Stratified Squamous Epithelium: Multiple layers of flattened cells.
• Stem Cells: At the bottom layer of the epidermis continuously dividing and creating new skin cells
• Keratinization: New skin cells become flattened and hardened, pushed to the surface (Keratin)
• Prevention of Water Loss: Top layers are dead cells that are shed, ensuring minimal water loss from skin.

Skin: Dermis

• Structure: Thick, inner layer of skin, made of loose fibrous connective tissue, Contains elastic and collagen fibers.
• Function: Strength, elasticity, and nutrients to the skin; supports body temperature regulation and provides sensation; contains blood vessels, many sensory receptors, and glands.

Skin: Hypodermis

• Structure: Hypodermis/Subcutaneous Layer, fat and connective tissue.
• Function: Insulation and cushioning, energy storage, Anchoring skin to underlying structures, allowing flexibility and movement.

Cellular Junctions Review

• Occluding Junction: Seals the space between cells
• Cell-Cell Anchoring Junctions: Connect cells to each other
• Channel Forming Junctions: Allows the passage for small water soluble molecules
• Cell-Matrix Anchoring Junctions: Connecting cells to extracellular matrix.
• Tight Junction: Seals gaps between epithelial cells.
• Adherens Junction: Connects actin filaments between cells.
• Desmosome: Connects intermediate filaments between cells for mechanical strength.
• Gap Junction: Allows the passage of small water-soluble molecules between cells.
• Hemidesmosome: Anchors cells to the extracellular matrix.

Cellular Junctions Important for Skin

• Tight Junctions: Seal the space between adjacent cells.
• Desmosomes: Provide mechanical strength.
• Adherens Junctions: Maintain cell positioning and support wound healing.
• Gap Junctions: Channels for the passage of small water-soluble molecules.
• Hemidesmosomes: Anchor the basal layer of epidermis to the basement membrane.

ECM in the Skin

• Collagen: Provides tensile strength and resilience.
• Elastin: Provides elasticity and flexibility.
• Proteoglycans: Hyaluronic acids, hydrate the skin by binding to water.
• Fibronectin: Cell adhesion, migration, and migration.
• Integrin: Fibronectin receptor, anchors skin cells.

Epidermolysis Bullosa (EB)

• Overview: Group of genetic disorders.
• Signs and Symptoms: Blistering in response to minor trauma.
• Types:
  • EB Simplex: Most common, mildest form, mutations in keratin genes (KRT 5 and KRT 14).
  • Junctional EB: Blisters over a large area of the body, usually starts from birth or infancy, mutations in laminin 332.
  • Dystrophic EB: Blisters and scar formation, increased risk of skin cancer, mutations in collagen 7.

EB Simplex

• Description: Most common and mildest form of EB.
• Mutations: Keratin genes (KRT 5 and KRT 14).
• Effects: Mutant proteins -> increased fragility, blister formation (accumulation of fluid in the extracellular spaces)

Junctional EB

• Description: Blisters over a large area of the body; usually starts from birth or infancy.
• Mutations: Laminin 332 and Collagen 17.
• Effects: Both are involved in anchoring epiderms to basement membrane

Dystrophic EB

• Description: Blisters and scar formation, increased risk of skin cancer.
• Mutations: Collagen 7.
• Effects: Key role in maintaining structural integrity of the skin, cell signaling, and wound healing

Treatment and Therapy for EB

• Wound Care, Infection Prevention, Cell and Gene Therapy