Slide 1Chapter 5Ectoderm and MesodermAnswersThick and Thin SkinSlide 6FunctionsSlide 8Slide 9Slide 10Slide 11Slide 12EpidermisSlide 14Slide 15Layers of the epidermisStratum BasaleStratum SpinosumStratum GranulosumStratum LucidumStratum CorneumKeratinazationSlide 23MelaninLayers of the DermisEpidermal Growth Factor (EGF)Slide 27Epidermal Ridges form what?Slide 29HairWhat are the three types of hairs?Slide 32NailsStages of Forming of UlcersBurnsSlide 36Rule of NinesMadeline (Mattie) [email protected] SESSION 4Chapter 5•Ectoderm and Mesoderm•Types of skin (thin and thick)•6 Functions of skin•Layers of skin•Structure of skin•Epidermis layers•Dermis•Basis of skin color•SubQ layers•Accessories•Skin glands *Review•Nails •Ulcers and Burns•AgingEctoderm and Mesoderm•Ectoderm: _____ develops from this•____, ____, and skin ____ are _______ derivatives •Mesoderm: _____ develops from thisAnswers•Ectoderm: Epidermis develops from this•Nails, hair, and skin glands are epidermal derivatives •Mesoderm: The dermis develops from thisThick and Thin SkinCompare and contrast:-Which is hairy? Hairless?-Where are these types two types generally located?FunctionsWhat are the seven main functions of the skin?1) Regulation of Body Temperature2) Blood Reservoir3) Protection of Underlying Tissue and Organs4) Cutaneous Sensations5) Excretion 6) Absorption7) Synthesis of Vitamin of DWhat are the two main layers of the skin? What do they consist of?•The skin consists of two main parts–Epidermis•Thinner portion; composed of epithelial tissue•avascular–Dermis•Thicker portion•vascular•Subcutaneous layer/hypodermis–Deep to the dermis, but NOT part of the skin–Consists of areolar and adipose tissue–Serves as a storage depot for fat–Contains large blood vessels that supply the skinEpidermis•Composed of keratinized stratified squamous epithelium•Contains four principal types of cells–Keratinocytes (90%)–Melanocytes –Langerhans cells–Merkel cellsCell FunctionKeratinocytes (90%)Produces keratin, a tough fibrous protein, that helps protect the skin and underlying tissues from heat, microbes, abrasions, and chemicalsMelanocytes (8%)Contributes to skin color and helps absorb ultraviolet light; protect keratinocytes by guarding the nucleus (DNA)Langerhans cellsHelp other cells of the immune system recognize an invading microbe and destroy itMerkel cellsDetect touch sensationsLayers of the epidermis•Stratum basale/germinativum•Stratum spinosum•Stratum granulosum•Stratum lucidum•Stratum corneumBakers sell goodies like cookiesStratum-a horizontal layer of materialStratum Basale•Have some stem cells that produce new keratinocytes•Keratin intermediate filaments attach to desmosomes, binding to adjacent layers•Melanocytes and Merkel cells are scattered among this layerStratum Spinosum•Mainly consists of keratinocytes (8-10 layers)•Keratinocytes produce coarser bundles of keratin than that of the basal layer•Desmosomes for connection•Langerhans cells and melanocytesStratum Granulosum•3-5 layers of flattened keratinocytes, which are undergoing apoptosis (WHY?)•Keratohyalin- assembles kif into keratin•Lamellar granules- produces a lipid-rich secretion that acts as a repellent sealant, retarding loss and entry of water and foreign materials•Marks the transition between the metabolically active and the more superficial dead cellsStratum Lucidum•Consists of 4-6 layers of flattened, clear dead keratinocytes- contain large amounts of keratin and thickened plasma membranes•Present ONLY in the thick skin of areas such as–Fingertips, palms, and solesStratum Corneum•Average of25-30 layers of flattened dead keratinocytes•Can range from a few cells in thin skin to 50 or more layers in thick skin•Result of apoptosis•Cell are continuoulsy shed and replaced by cells from the deeper strata•Friction produces callusesKeratinazationKeratin production apoptosisSloughing ofReplaced by new cellskeratinizationThis process takes about 4-6 weeksWhy do the cells of the stratum basale have the most cell division?What happens when the superficial dead layers of the epidermis are stripped away?What is dandruf?Melanin•The number of melanocytes is about the same in all people•You have a set amount of melanocytes from birth to death•The diference in skin pigmentation is due to the amount of melanin produced•Melanocytes synthesize melanin from the amino acid tyrosine in the presense of an enzyme called tyrosinase•Increased exposure to UV light increases enzymatic activity increases melanin productionLayers of the DermisEpidermal Growth Factor (EGF)•Promotes ______•Accelerates ______•Stimulates ______•Used to grow skin grafts•Produced by glands•Powerful peptide growth factor•Promotes division of germinative cells •Accelerates keratin production •Stimulates epidermal repair and glandular secretionEpidermal Ridges form what?Form the basis of fingerprints and footprints and increase firmness of gripHairWhat are the three types of hairs?•Lanugo- fine downy hairs that cover the fetus •Vellus- short fine hairs that are barely visible to the naked eye •Terminal- long course very pigmented hairsNailsStages of Forming of Ulcers•Stage I: A reddened area on the skin that, whenpressed, does not turn white. This indicates that a pressure ulcer is starting to develop.• Stage II: The skin blisters or forms an open sore. The area around the sore may be red and irritated.• Stage III: The skin breakdown now looks like a crater. There is damage to the tissue below the skin.• Stage IV: The pressure ulcer has become so deep that there is damage to the muscle and bone, and sometimes to tendons and joints.Burns •First-degree: damage only the epidermis• Second-degree: damage the epidermis and the dermis (blisters) [papillary-clear/reticular-bloody]• Third-degree: damage or destruction to the hypodermis (full thickness) [white to black]Rule of