Skin Layer Notes PDF

Skin Layer Notes Epidermis Stratum Corneum (Layer 1) ○ Thickest layer of the epidermis. ○ Composed of scalelike cells full of keratin that constantly flake off.  Stratum Lucidum (Layer 2) ○ Present in thick skin and lacks hair. ○ Contains tran...

Skin Layer Notes Epidermis Stratum Corneum (Layer 1) ○ Thickest layer of the epidermis. ○ Composed of scalelike cells full of keratin that constantly flake off.  Stratum Lucidum (Layer 2) ○ Present in thick skin and lacks hair. ○ Contains translucent cells with keratin. Stratum Granulosum (Layer 3) ○ Contains granulocytes. Stratum Spinosum (Layer 4) ○ Mitotic layer with football-shaped cells. Stratum Basale (Layer 5) ○ Most inferior epidermal layer. ○ Involved in rapid cell division. ○ Site of melanin formation (contains melanocytes). Dermis Papillary Layer (Layer 6) ○ Contains Meissner's corpuscles (touch receptors). ○ Responsible for fingerprints. Reticular Layer (Layer 7) ○ Vascular region of the dermis. ○ Contains Pacinian corpuscles and thermoreceptors. ○ Site of elastic and collagen fibers, providing mechanical strength. ○ Sebaceous glands found here. Hypodermis Layer Below Skin (Layer 10) ○ Composed primarily of adipose tissue. ○ Blood is shunted here when the skin is cold. Other Basement Membrane ○ Lies just below the Stratum Basale (Layer 5). Overall Layers Epidermis (Overall Layer 8) Dermis (Overall Layer 9) Pigmentation 1. Cyanosis ○ Refers to the bluish coloration seen in lips and nail beds when blood oxygen levels are low. 2. Bilirubin  ○ Pigment that causes yellowing of the skin and eyes due to accumulation of waste from broken down hemoglobin. 3. Hemoglobin ○ Visible through the skin; changes skin pigmentation with variations in skin temperature. 4. Melanin ○ Primary pigment responsible for skin coloration. 5. Epidermis ○ The layer of skin that contains melanin pigment. 6. Jaundice ○ Yellowing of the skin experienced by premature infants due to the liver's inability to process fetal hemoglobin quickly. Skin Function and Structure 1. Heat Regulation ○ The skin helps regulate body heat through radiation from the surface and evaporation of sweat. 2. Cyanosis ○ A bluish cast of the skin resulting from inadequate oxygenation of the blood. 3. Freckle ○ A localized concentration of melanin. 4. Keratin ○ The waterproofing protein found in epidermal cells. 5. Melanin ○ Shields DNA of living skin cells from damage caused by ultraviolet (UV) radiation. 6. Vitamin D ○ Manufactured in the skin through the conversion of cholesterol with exposure to UV radiation. 7. Keratin (repeated concept) ○ Helps prevent desiccation and protects the body from pathogens, chemicals, and mechanical damage. 8. Adipose Tissue ○ Fat in the adipose tissue layer beneath the dermis helps to insulate the body. 9. Elastic Fibers ○ Wrinkling of the skin is due to the loss of elastic fibers