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Integumentary System Skin and Its Appendages Anatomy & Physiology Skin or Integument Largest organ in the body Integumentary System: denotes the skin and its appendages Structure of the skin Layers of the skin Epidermis: Outer, thinner layer Dermis: Thicker layer, connective tissue Hypodermis: Subcutaneous layer, superficial fascia Thick Skin Refers to epidermal layer only Found: palms of hands, soles of feet, fingertips Each of the 5 layers present Dermal papillae: fingerprints No hair Cell Types of Epidermis Keratinocytes: contain keratin, make up 90% of epidermal cells Melanocytes: contribute color to skin Langerhans cells: immunological reactions in skin Cell Layers of Epidermis Stratum corneum Stratum lucidum Stratum granulosum Stratum spinosum Stratum basale Stratum corneum (horny layer) Flat thin squamous cells Surface cells dead & continually being shed Cytoplasm in cells replaced by keratin Desmosomes hold cells together Barrier layer of the skin Stratum lucidum (clear layer) Nuclei absent Cells contain eleidin which will be transformed to keratin Blocks water penetration or loss Absent from thin skin Stratum granulosum (granular layer) Keratinization begins 2-4 layers deep Maybe absent in thin skin Cells filled with granules called keratohyalin Stratum spinosum (spiny layer) 8-10 layers with prominent desmosomes which appear spiny under a microscope Cells rich in RNA Stratum basale (base layer) Single layer of columnar cells Only cells which undergo mitosis Cells migrate from basal layer thru the outer layers Dermal-Epidermal Junction Contains basement membrane Also contains a polysaccharide gel that “glues” 2 layers together Dermis Thin papillary layer & thick reticular layer Thickest on soles & palms Thinnest on eyelids & penis Mechanical strength of skin Papillary layer Forms the bumps, dermal papillae which project into epidermis Allows us to grip surfaces & creates fingerprints Reticular layer More dense collagen & elastic fibers Serves as point of attachment for muscle fibers Skeletal muscle: muscles of facial expression Smooth muscle: arrector pili muscles on hair follicles Skin Color Determined by quantity of melanin in cells of epidermis All races have about the same number of melanocytes but differ in amount of melanin produced Sun can increase melanin production Functions of skin Protection Sensation Movement without injury Vitamin D production Excretion Immunity Temperature regulation Heat Loss Evaporation Radiation Conduction Convection Burns Predict body surface area to determine how much fluid to replace: Rule of palms (1%) Rule of nines First degree burn Involves only the epidermis No blistering or scarring Sunburn Reddening of the skin, mild discomfort Second degree burn Involves epidermis & dermis Blistering, pain, swelling May scar Third degree burn Destruction of epidermis & dermis, may involve underlying tissue Severe scarring Appendages of the skin Hair Nails Skin glands Hair Lanugo hair: fine hair covering fetus Vellus hair: replacement for lanugo hair, first appears on scalp, eyelids, eyebrows Terminal hair: Coarse hair that replaces vellus hair-axillary, pubic, beard, chest & hair on arms & legs in men Hair follicle Stratum germinativum develops into follicle's inner layer and forms the germinal matrix Small mound of dermis protruding into germinal matrix is the papilla (contains blood capillaries) Nails Parts of the Nail Matrix- the thickened, proximal area of the nail that is responsible for growth Bed- the hard translucent visible part of the nail Root- the point of attachment under the skin Cuticle- the layer of skin that prevents dirt and bacteria from getting into the nail bed Free Body- the end of the nail that is not connected to the skin Glands Sweat or sudoriferous glands Eccrine sweat gland Apocrine sweat glands Sebaceous glands Ceruminous glands Eccrine sweat glands Most numerous Over most of the body Secretory portion located in the subcutaneous tissue Simple coiled tubular gland Apocrine Sweat glands Found in armpit, areola of breast, around the anus Large than eccrine Connected with hair follicles Sebaceous glands Secrete sebum into each follicle Ceruminous glands Modification of apocrine sweat glands Open into ears Produce cerumen Image Citations Slide 1: cross section of skin, 7/12/06, http://vilenski.org/science/humanbody/hb_html/skin.html Slide 3: Anthony’s Textbook of Anatomy & Physiology, Seventeenth Edition by Thibodeau & Patton, Chapter 6. Slide 5: Thick skin, 7/30/06, http://erl.pathology.iupui.edu/HISTO/LABE151.HTM Slide 6: Melanocytes, 7/30/06, http://www.lab.anhb.uwa.edu.au/mb140/CorePages/Integumentary/Integum.htm Slide 7: Thick skin trichrome, 7/30/06, http://www.lab.anhb.uwa.edu.au/mb140/CorePages/Integumentary/Integum.htm Slide 8: Slide 43, Thick skin, 7/30/06, http://w3.ouhsc.edu/histology/Glass%20slides/43_09.jpg Slide 9: Stratum lucidum human foot, 7/30/06, http://oregonstate.edu/~hanba/Projector%20Slides/Projector%20Slides/Skin%20Stratum%20L ucidum%20Human%20Foot-2.jpg Slide 10: Stratum granulosum, 7/30/06, http://anatomy.iupui.edu/courses/histo_D502/D502f04/Labs.f04/Lab14/s31.100x.i3.jpg Slide 11: Stratum spinosum, 7/30/06, http://anatomy.iupui.edu/courses/histo_D502/D502f04/Labs.f04/Lab14/s31.100x.i2.jpg Slide 12: Stratum basale, 7/30/06, http://online-media.unimarburg.de/histologie/introhis/HIS/skin/skin06.gif Slide 14: Dermis, 7/30/06, http://sprojects.mmi.mcgill.ca/dermatology/dermis.htm Slide 15: Dermis, 7/30/06, http://neuromedia.neurobio.ucla.edu/campbell/skin/wp_images/7%20dermis.jpg Slide 16: 7/30/06, http://www.potterleague.org/Potter_Kids_Final/pet_body_lang.htm Image Citations Slide 20: Wallace’s rule of nines, 7/30/06, http://www.sunmed.org/burns.html Slide 21: First degree burn, 7/30/06, http://www.grossmanburncenter.com/origsite/web/care/causes.htm Slide 22: Burn symptoms, 7/30/06, http://www.maggiessecret.com.au/burnsscalds.aspx Slide 23: Third degree burn, 7/30/06, http://www.grossmanburncenter.com/origsite/web/care/causes.htm Slide 26: Thibodeau & Patton, Anthony’s Textbook of Anatomy & Physiology, Seventeenth Edition. Slide 27: Thin Skin, 7/30/06, http://biology.clc.uc.edu/fankhauser/Labs/Anatomy_&_Physiology/A&P201/Integu mentary/hair_follicle_100x_PA112040labeled.JPG Slide 28: Sebaceous gland and shaft of hair follicle, 7/30/06, http://www.keele.ac.uk/depts/ms/resources/anatomy/histologyimages/t146.html Slide 29: “Structure of nails”, Thibodeau & Patton, Anthony’s Textbook of Anatomy & Physiology, Seventeenth Edition. Slide 31: “Skin Glands”, Thibodeau & Patton, Anthony’s Textbook of Anatomy & Physiology, Seventeenth Edition. Slide 32: Dermis (Apocrine sweat glands), 7/30/06, http://www3.umdnj.edu/histsweb/lab11/lab11apocrine.html