integumentary system

• dermis


  connective tissue
• accessory structures of skin

  hair, sebaceous glands, sensory receptors, arrector pili muscles, sweat glands, blood vessels
• epidermis 


  stratified squamous keratinised epithelium
• papillary layer


  loose connective tissue
• reticular layer


  dense irregular connective tissue
• hypodermis


  adipose and dense irregular connective tissue
• keratinocytes appear by division of stem cells in the stratum basale, and are pushed towards the surface
• keratinocytes fill with tonofilaments (intermediate filaments) and keratohyalin granules, and secrete lamellar bodies
• stratum basale


  has hemidesmosomes, desmosomes, melanin, cells undergo mitosis
• non-keratinocytes


  melanocytes and merkel cells
• stratum spinosum


  cells are in constant contact by intercellular bridges, held together by desmosomes, cells contain tonofilaments, langerhans cells are found here
• stratum granulosum 


  produces keratin and water proofing sustances, contains basophilic keratohyaline granules, tonofilamets, and lamellar bodies
• keratohyaline granules and tonofilaments combine when the cell dies to form keratin
• lamellar bodies are released at cell death and contain water proofing glycophosopholipids
• stratum corneum


  dead cells filled with keratin
• basal cell turnover to keratin takes 25-30 days with lots of friction, and 40-50 days in areas of less friction
• melanocytes


  dendritic cells that produce melanin and transfer the melanin to the keratinocytes
• eumelanin


  brown and black
• pheomelanin


  red colour to skin
• grey hair


  black eumelanin without other melanin
• blonde hair


  brown eumelanin without other melanin
• red hair


  small amount of brown eumelanin with pheomelanin
• langerhans cell


  dendritic cells, found in all layers but best identified in the spinosum, function as antigen presenting cells
• merkel cells


  in basal layer, associated with end of a sensory neuron, respond to light touch
• lucidum and corneum is thicker in thick skin
• dermal papillae are greatly developed in thick skin, allowing for a firm attachment of epidermis to dermis
• the papillary layer forms the dermal papilla and epidermal pegs
• free nerve endings


  finish in dermis and epidermis, detect temperature and pain
• meissners corpuscle 


  found in papillary dermis, detect touch
• pacinian corpuscle 


  found deep in dermis or hypodermis, detect pressure and vibration
• hair bulb


  growing point, deep in reticular dermis or hypodermis
• arrector pili muscle


  smooth muscle that attaches to CT sheath on hair, and inserts into papillary
• melanocytes are found in the hair bulb
• epidermal keratin is less sulphated and therefore softer than hair and nail keratin
• sebaceous gland secretion


  holocrine of sebum
• eccrine sweat gland secretion

  merocrine secretion of sweat
• apocrine sweat gland secretion


  merocrine secretion of sweat (emotional)
• sebaceous gland structure


  simple branched acinar
• eccrine sweat gland structure

  simple coiled tubular, secretory portion deep in the dermis
• eccrine sweat glands dark cells

  proteinaceous