Integumentary System Apparently there is no chapter/section for this in the book? Integument the skin and all accessory structure (hair, feathers, scales) Skin The largest vertebrate organ major part of the integument system Vertebrate integument and derivatives Functions Protection form abrasion protects against water loss barrier to disease causing pathogens protection from UV light temperature regulation contains sensory receptors excretion (limited) Vertebrate Integument skin and all other accessories skin is the largest organ o vertebrates skin consists of 2 layers epidermis dermis Epidermis outer layer nutrients diffuse into the epidermis form the dermis stratified squamous epithelial cells Cell types langerhans cells defensive cells Melanocytes produce pigment melanin skin coloration protect form UV light Merkel cells touch receptors Keratinocytes primary cell type produce insoluble protein Keratin amount of keratin increases from the inside to outside keratin fill cytoplasm and impairs nutrient diffusion, cell dies Dermis Inner layer of skin thinner than dermis highly vascularized contains: sensory structures vessels nerves glands Origin of hair/scales/feathers in vertebrates Sensory structures Meissner's corpuscles light touch Pacinian corpuscles deep vibrations Sweat Glands temperature regulation produce sweat (primarily water) evaporating cooling release of waste ions 2.5 million on the body release of heat Sebaceous Glands all over body, except palms and soles large on face, neck, and upper chest produce sebum lubricates and soften hair and skin water proofing in aquatic mammals Hypodermis subcutaneous layer below the dermis not a layer of the skin contains much adipose (fat) tissue females have thicker layer of adipose tissue than males Function body contour insulation support the skin