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E ver wondered about the layers that make up your skin, the body’s biggest organ? It’s like a tough shield, protecting us from the world outside. But have you ever really thought about how these layers work together to keep us safe? There are three main layers: the epidermis, the dermis, and the subcutaneous layer. Let’s dive in and discover more about your amazing skin!

1. The Protective Shield – Epidermis:

The epidermis is an elastic layer on the outside that is continually being regenerated

    • Thickness: The epidermis, ranging from a mere 0.1mm on delicate eyelids to around 0.3mm on sturdy palms and soles, is the sentinel of our skin.
    • Functions: It’s your frontline defense, shielding you from the harsh sun, pesky germs, and that sneaky water loss.
      • Barrier: Acts as a barrier, shielding the body from harmful UV rays, pathogens, and dehydration.
      • Thermoregulation: Regulates temperature and prevents water loss.
      • Melanin Production: Contains melanocytes that produce melanin, providing protection against UV radiation.
  • Constituent Cell Types: 
    • Keratinocytes: The most abundant cells in the epidermis, producing the protein keratin for structure and water resistance.
    • Melanocytes: Responsible for producing melanin, giving skin its pigment and UV protection.
    • Langerhans cells: Form part of the immune system, detecting pathogens and foreign substances in the skin.
    • Merkel cells: Found in touch-sensitive areas, aiding in sensory perception.

Layers of Epidermis

  • 1.1 Stratum Corneum
    • The outermost layer of the epidermis composed of dead skin cells (corneocytes) that are continuously shed and replaced.
    • Acts as a protective barrier against environmental factors, pathogens, and water loss. Its thickness can vary depending on body parts and environmental exposure.
  • 1.2 Stratum Lucidum
    • A translucent layer that provides additional protection and stability to the skin.
  • 1.3 Stratum Granulosum
    • This layer has tiny granules of keratin and fats that help to make the skin waterproof and keep its shape.
  • 1.4 Stratum Spinosum
    • Consists of living keratinocytes that provide strength and flexibility to the skin.
    • They are held together by special connectors called desmosomes, which make the skin firm.
  • 1.5 Stratum Basale
    • The innermost layer where new skin cells (keratinocytes) are formed through cell division. These cells undergo a maturation process as they move towards the surface.
    • Contains melanocytes responsible for producing melanin, which provides protection against UV radiation.

2. The Supportive Network – Dermis:

Aka the inner layer

  • Thickness: Beneath the epidermis lies the dermis, with a thickness ranging from 0.6mm to 3mm, depending on body location.
  • Functions:
    • Structural Support: Provides structural support and elasticity to the skin through collagen and elastin fibers.
    • Nutrient Delivery: Houses blood vessels that deliver nutrients and remove waste products.
    • Accessory Structures: Contains Sebaceous glands, Sweat glands and Hair follicles.
  • Constituent Cell Types: Fibroblasts crafting collagen, Adipocytes for those cushy curves, Mast Cells ready to sound the alarm, and Blood Vessels delivering the goodies.

3. The Cushioning Layer – Hypodermis (Subcutaneous Tissue):

Aka the connective tissue and fat

    • Thickness: The deepest layer of the skin, the hypodermis, can vary significantly in thickness, primarily composed of adipose tissue.
    • Functions: It’s your body’s cushiony mattress, storing energy, keeping you warm, and offering a soft landing.
      • Energy Storage: Acts as an energy reservoir, storing fat for insulation and energy.
      • Protection: The hypodermis cushions internal organs, regulates body temperature, and aids in maintaining homeostasis.

Your skin does so much more than just look pretty!

It’s your body’s superhero shield! It protects you from bumps, heat, and other outside threats. Plus, it locks in moisture, shields you from the sun’s harmful rays, and even lets you feel things like touch and temperature changes. On top of all that, it also helps keep your body temperature just right and acts like a detective, spotting any sneaky infections trying to sneak in. Treat your skin right by knowing what it loves and what it doesn’t! Here’s a little something to ponder:

"Do you know when people are talking about the skin barrier, which layer are they referring to?"

Think about it and share your thoughts with me!

Karen Chow

IFSCC, HKSCC, CSCC Cosmetic Scientist, Co-Founder of TiN5