Skin Structure: Epidermis and Sublayers

Skin Structure

• Epidermis: outermost layer, composed of stratified squamous epithelium, lacking blood vessels
  • Divided into several sublayers:
    • Stratum corneum: outermost sublayer, composed of dead, keratinized cells
    • Stratum lucidum: clear layer, found only in thick skin
    • Stratum granulosum: granular layer, containing keratinocytes with granules
    • Stratum spinosum: spinous layer, composed of polygonal cells
    • Stratum basale: basal layer, composed of cuboidal or columnar cells
• Dermis: layer beneath epidermis, composed of connective tissue
  • Divided into two sublayers:
    • Papillary dermis: thin, loose connective tissue, containing hair follicles and sebaceous glands
    • Reticular dermis: thicker, denser connective tissue, containing blood vessels and nerve endings
• Hypodermis: subcutaneous tissue, composed of loose connective tissue and adipose tissue

Skin Functions

• Protection:
  • Physical barrier against external factors (mechanical, thermal, chemical)
  • Prevents water loss and entry of foreign substances
• Regulation of Body Temperature:
  • Sweat evaporation helps cool the body
  • Blood vessels constrict or dilate to conserve or release heat
• Sensory Function:
  • Contains sensory receptors for touch, pressure, temperature, pain, and itch
• Vitamin D Production:
  • Exposure to UV radiation triggers vitamin D synthesis
• Waste Removal:
  • Sweat helps remove waste products, such as urea and lactic acid
• Immune Function:
  • Langerhans cells and other immune cells help defend against pathogens

Skin Structure

• The epidermis is the outermost layer of the skin, composed of stratified squamous epithelium without blood vessels.
• The epidermis has five sublayers: stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, and stratum basale.
• The stratum corneum is the outermost sublayer, consisting of dead, keratinized cells.
• The stratum lucidum is a clear layer found only in thick skin.
• The stratum granulosum is the granular layer, containing keratinocytes with granules.
• The stratum spinosum is the spinous layer, composed of polygonal cells.
• The stratum basale is the basal layer, composed of cuboidal or columnar cells.
• The dermis is the layer beneath the epidermis, composed of connective tissue.
• The dermis has two sublayers: papillary dermis and reticular dermis.
• The papillary dermis is a thin, loose connective tissue layer, containing hair follicles and sebaceous glands.
• The reticular dermis is a thicker, denser connective tissue layer, containing blood vessels and nerve endings.
• The hypodermis is the subcutaneous tissue, composed of loose connective tissue and adipose tissue.

Skin Functions

• The skin provides physical protection against mechanical, thermal, and chemical external factors.
• The skin prevents water loss and entry of foreign substances.
• Sweat evaporation helps cool the body, regulating body temperature.
• Blood vessels constrict or dilate to conserve or release heat, regulating body temperature.
• The skin contains sensory receptors for touch, pressure, temperature, pain, and itch.
• Exposure to UV radiation triggers vitamin D synthesis in the skin.
• Sweat helps remove waste products, such as urea and lactic acid, from the body.
• The skin has immune function, with Langerhans cells and other immune cells helping defend against pathogens.

Explore the layers of the epidermis, the outermost layer of the skin, including the stratum corneum, stratum lucidum, and more. Learn about the composition and characteristics of each sublayer.