Level 4 Glossory

Bilayer Lipid and Intercellular Matrix

• Function: Prevents water loss between cells.

• Epidermal Lipids: Part of the acid mantle that helps in preventing water loss.

Key Lipids

• Ceramides: Natural waxy lipids that help retain water.

Melanogenesis

• Definition: Formation of melanin.

• Tyrosine: Amino acid that forms melanin.

  • Melanosomes: Contain pigment.

    • Eumelanin: Brown to black pigment (found in Fitzpatrick skin types 5 & 6).

    • Pheomelanin: Yellow to red pigment (found in Fitzpatrick skin types 1 & 2).

Dermal Structure

Papillary Layer

• Composition: Loose areolar tissue, young collagen, elastin, fibroblasts, mast cells, white blood cells, GAGs.

Dermal-Epidermal Junction (DEJ)

• Connection: Attaches epidermis & dermis with desmosomes.

• Collagen Types: 5, 7, 17 present.

Reticular Layer

• Characteristics: Largest part of the dermis with mature collagen types 3, elastin, GAGs.

• Defense Cells: Includes mast cells, phagocytes, leukocytes, lymphocytes.

Elastosis

• Description: Increased elastin leading to yellow, thickened skin; fibers become twisted.

Natural Barrier Function

• Role: First line of defense against environmental factors.

  • Chemical: Acid mantle and natural microbiota (e.g., P. acne for protection and healing).

  • Physical: Lipid bilayer and epidermal lipids provide waterproof barrier.

Trans Epidermal Water Loss (TEWL)

• Function: Prevents water loss through the epidermis.

Natural Moisturizing Factor (NMF)

• Function: Retains water in the stratum corneum, beginning in the granular layer.

• Lamellar Cells: Secrete lipids, enzymes, and proteins.

• Fillaggrin Proteins: Form water-retaining amino acids.

P. Acne

• Location: Found at the opening of the sebaceous gland; contributes to skin health.

Anaphylactic Shock

• Description: Severe allergic reaction characterized by:

  • Difficulty in swallowing and speaking.

  • Increased heart rate, sickness, weakness, potential collapse.

• Response: Immediate removal of the allergen.