IMG_3213.jpeg

# Epidermis **Keratinized Stratified Squamous Epithelium** * 5 layers of thick skin (hands and feet) * No oil glands * No hair follicles **Layers (Superficial to Deep):** * **Stratum Corneum:** Replaced approximately every 4 weeks * **Stratum Lucidum:** Present only in thick skin * **Stratum Gra...

# Epidermis **Keratinized Stratified Squamous Epithelium** * 5 layers of thick skin (hands and feet) * No oil glands * No hair follicles **Layers (Superficial to Deep):** * **Stratum Corneum:** Replaced approximately every 4 weeks * **Stratum Lucidum:** Present only in thick skin * **Stratum Granulosum** * **Stratum Spinosum** * **Stratum Basale:** Connects to the dermis **Cellular Components:** * **Stem Cells:** Located only in the stratum basale. These are highly mitotic and give rise to keratinocytes. * **Keratinocytes:** Found in all layers. They produce keratin. * **Melanocytes:** Located in the stratum basale. These produce the pigment melanin. * **Tactile (Merkel) cells:** Found in the stratum basale, these cells respond to touch, abundant on hands and feet. * **Dendritic (Langerhans) cells:** Located in the stratum spinosum and stratum granulosum, playing an immune role. * **Macrophages (WBC):** Engulf bacteria, foreign particles, and damaged cells that enter the skin from other places. **Continuous Turnover** Cells from the stratum basale continuously replace the upper layers of the skin. "Born" in the stratum basale, keratinocytes undergo mitosis to continuously regenerate. Tactile (Merkel) cells and melanocytes are also located in this deepest layer. The epidermis contains epidermal ridges.