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Week 3 Chapter 5_ The Integumentary System.docx - Week 3...

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Week 3 Chapter 5: The Integumentary SystemIntroductionThe organs of the integumentary system include theNote that all 4 of the basic tissue types are well-represented in thisorgan system:Epithelium in thehair, nails, and the epidermis of the skin; thedermis contains C.T.;muscle is found attached to the hairfollicles, and in the substance of arteries and veins;nerves provide an abundance of sensation.Dermatologyis the medical specialty for the diagnosis and treatment of disorders of the integumentarysystemThe integument can also be thought of as acutaneous membranethat covers the outer surface of thebody.Cutaneous membrane: It is the largest organ by surface area and weight.We lose almost a kg of skin epithelium a year that becomes a major part of household “dust”.Besidesprotection, the skin functions in:Regulation of body temperatureSensory perceptionsSynthesis of vitamin DEmotional expressionIt also serves as an important reservoir of blood.Structures of the skinThe skin has 2 major layers:The outer, thinner layer is called theepidermisand consists of epithelial tissue.The inner, thicker layer is called thedermisand consists of C.T.The subcutaneous(subQ)layer (also called the hypodermis) is located underneath the dermis.It is a loose areolar/adipose C.T. that attaches the skin to the underlying tissues and organs.Layers of the SkinEpidermis is avascular –The epidermis is composed of keratinized stratified squamous epithelium which contains fourmajor types of cells:Keratinocytes:Melanocytes:Intraepidermal macrophagesTactile epithelial cellsDermis is vascularcauses bleedingHas areolar (beneath the epidermis layer and is epithelial) and adipose tissuestissue made up of fat cells)meaning holds them in place and serves as a reservoir for surround the tissueFibres extending from the dermis anchor the skin to the hypodermis, which attaches to theunderlying fascia, which is the connective tissue around muscles and bonesHypodermis serves as a storage site for fat and contains large blood vessels that supply the skinHypodermis/Subcutaneous LayerThe hypodermis, and sometimes the dermis, contains nerve endings called lamellated (Pacinian)corpusclesResponsible for sensitivity to vibration and pressureEpidermal CellsKeratinocytesmake up 90% of the cells. They produce keratin - a tough fibrous protein that providesprotection from heat, abrasion, microbes, and chemicals
Releases water which reduces water entrylamellar grumblesMelanocytesproduce the pigmentmelaninthat protects against damage by ultraviolet radiation andcontributes to skin colourBECAUSE THEY ARE SUSCEPTIBLE TO DE=AMAGE BY UV LIGHT MELININE HELPS SUN DAMAGELangerhans cellsaremacrophagesthat originated in the red bone marrow. They are involved inimmune responses.

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