Integuement System Flashcards
Functions of Skin
Thermoregulation
Protection
Environmental sensory input
Excretion (water and salts)
Immunity (specialized cells in epidermis are part of immune system)
Blood reservoir (vessels in dermis hold up to 10% of blood)
Vit D synthesis (UV radiation activates skin molecule that is a precursor to Vit D)
Epidermis
Superficial
Avascular epithelial tissue (depends on dermis for oxygen and nutrients)
Cells in epidermis
Keratinocytes
Melanocytes
Langerhans cells
Merkel cells
Keratinocytes
Produce keratin that helps waterproof skin
Melanocytes
Transfer skin pigment melanin to kertinocytes
Langerhans Cells
Interact with helper T cells
Merkel Cells
Attach to sensory neurons and function in touch sensation
Hair
Unique to mammals
Layers of Epidermis
Stratum Corneum (superficial)
Stratum lucidum
Stratum granulosum
Stratum spinosum
Stratum basale (deepest)
Stratum Corneum
25-30 dead layers
Filled with keratin and surrounded by lipids
Lamellar granules= water repellent
Stratum Lucidum
Only in palms, soles of feet, finger tips
3-5 layers of clear/dead cells
Stratum Granulosum
3-5 layers of dying cells
Lamellar bodies released by hydrophobic lipids
Stratum Spinosum
Strength and flexibility
8-10 layers held together by desmosomes (keratin involving adhesion proteins)
Stratum Basale
Germinativum
Contains Merkel cells and stem cells that divide to produce kertinocytes
Attached by basement membrane
Movement of Keratinocytes
Pushed to top layer
Rise—> accumultae and die—> lose cytoplasm, nucleus, other organelles–> slough off body
