INTEGUMENTARY SYSTEM SKIN& BODY MEMBRANES

MEMBRANES Structure: Thin, sheet like structureStructure: Thin, sheet like structure Functions:Functions: –Cover and protect the body surface –Line the body cavities –Cover the inner surface of the hollow organs (digestive, reproductive, respiratory) –Anchor organs to each other or to bones –Cover internal organs –Secrete lubricating fluids that reduce friction during organ movements

Two Types of Body Membranes Epithelial MembranesEpithelial Membranes –Cutaneous membrane (skin) –Serous membranes (protection/reduce friction for organs) –Mucous membrane (line body surfaces opening directly to the exterior– such as the esophagus; mucus secretion) Connective Tissue Membrane (no epithelium)Connective Tissue Membrane (no epithelium) –Smooth & slick, secrete synovial fluid –Reduce friction b/w opposing bones, line bursa sacs

SEROUS MEMBRANES Two Layers:Two Layers: –Visceral: covers the surface of the organ –Parietal: lines the walls of the body cavity Thoracic Cavity=PleuraThoracic Cavity=Pleura Abdominal Cavity=PeritoneumAbdominal Cavity=Peritoneum

SKIN FUNCTIONSFUNCTIONS –Protection against microbes, UV rays, harmful chemicals, cuts & tears –Temperature regulations –Sense organ activity: touch, pressure, pain, temperature –Metabolic functions: synthesis of vitamin D

Skin: Structure Two Layers:Two Layers: –Epidermis outermost & thinnestoutermost & thinnest cells are very tightly packedcells are very tightly packed –Dermis deep & thickdeep & thick primarily connective tissueprimarily connective tissue loosely packedloosely packed Hypodermis (adipose tissue)Hypodermis (adipose tissue) –Deep to the skin/dermis –Layer of insulation

Epidermis Stratum CorneumStratum Corneum Stratum LucidumStratum Lucidum Stratum GranulosumStratum Granulosum Stratum SpinosumStratum Spinosum Stratum Germinativum/BasaleStratum Germinativum/Basale

Stratum Germinativum/Basale Contains mainy germinativum (stem) cellsContains mainy germinativum (stem) cells Cells undergoing mitosisCells undergoing mitosis Forms strong bond between epidermis & dermisForms strong bond between epidermis & dermis Merkel CellsMerkel Cells  Touch receptors MelanocytesMelanocytes  Contain pigment melanin  Scattered throughout basale layer

Stratum Spinosum “ Spiny Layer”“ Spiny Layer” Produced by division of stratum germinosumProduced by division of stratum germinosum 8-10 layers of keratinocytes bound by desmosomes8-10 layers of keratinocytes bound by desmosomes Cells begin to shrink until cytoskeletons stick out (spiny)Cells begin to shrink until cytoskeletons stick out (spiny) Cells continue to divide – increasing thickness of skinCells continue to divide – increasing thickness of skin Langerhans CellsLangerhans Cells  Active in immune response

Stratum Granulosum “Grainy Layer”“Grainy Layer” Produces KeratinProduces Keratin KeratinKeratin  Tough, fibrous protein  Makes up hair, nails Cells dehydrate & dieCells dehydrate & die Create tightly interlocked layer of keratinCreate tightly interlocked layer of keratin

Stratum Lucidum “Clear Layer”“Clear Layer” Found only in thick skinFound only in thick skin Thick SkinThick Skin  Palms of hands  Soles of feet  5 layers of keratinocytes Covers stratum granulosumCovers stratum granulosum Cells are flat, dense, filled with keratinCells are flat, dense, filled with keratin

Stratum Corneum “Horny Layer”“Horny Layer” Exposed surface of skinExposed surface of skin Composed of dead cellsComposed of dead cells layers of keratinized cells15-30 layers of keratinized cells Water resistantWater resistant Shed & replaced every 2 weeksShed & replaced every 2 weeks

Dermis Collagen, elastin fibers– scatteredCollagen, elastin fibers– scattered

Dermal-epidermal junction Dermal papillae: parallel rows of peg-like projectionsDermal papillae: parallel rows of peg-like projections –Unique to each individual=Fingerprints

Dermis Specialized structures:Specialized structures: –Hair follicle: cells of the epidermis extend into the dermis forming a small tube –Hair bulb: base of the follicle –Hair papilla: cluster of cells (live); nourished by BV’s –Root: part of hair hidden in follicle –Shaft: visible part of hair

Dermis Specialized Structures (continued)Specialized Structures (continued) –Arrector pili: tiny, smooth muscle attached to base of dermal papillae & side of hair follicle Contracts: pulls on both simultaneously>>goosebumpsContracts: pulls on both simultaneously>>goosebumps

Nails Plates of epithelial cells with keratinPlates of epithelial cells with keratin Protect distal end of phalangesProtect distal end of phalanges Cells are keratinized in nail rootCells are keratinized in nail root Nail growth occurs in lanulaNail growth occurs in lanula Cuticle is fold of stratum corneum on proximal end of nailCuticle is fold of stratum corneum on proximal end of nail

Specialized Structures of the Dermis Sebaceous GlandsSebaceous Glands –Secrete oil (sebum) for hair/skin –Ducts open into hair follicles –Production controlled by hormones –Accumulated sebum enlarges ducts>>white heads –Darkened sebum>>black head

Specialized Structures of Dermis Sudoriferous GlandsSudoriferous Glands –Eccrine Glands WidespreadWidespread Watery Fluid; sweatWatery Fluid; sweat Stimulated by increased body temperatureStimulated by increased body temperature –Apocrine Glands Armpits/GenitalsArmpits/Genitals Thick/milky fluidThick/milky fluid Odor if bacteria presentOdor if bacteria present Stimulated by nerves during play, stress, sexual activityStimulated by nerves during play, stress, sexual activity

Pacinian Corpuscle: deep in the dermis; detects pressure

Close to the surface; light touch

Krause’s end bulb: touch/ low frequency vibration; cold

Thin Skin

Thick Skin

BlistersBlisters  Friction separates layers of epidermis or epidermis from dermis  Tissue fluid collects in space CallusesCalluses  Caused by pressure  Increase in pressure causes increased mitosis  Increased mitosis creates thicker epidermis Conditions

Conditions ImpetigoImpetigo Pink, water-filled lesionsPink, water-filled lesions Caused by staphylococcus infectionCaused by staphylococcus infection PsoriasisPsoriasis Chronic conditionChronic condition Caused by overproduction of skin cellsCaused by overproduction of skin cells

Excoriation Epidermis is missing, dermis is exposedEpidermis is missing, dermis is exposed Caused by mechanical means (scratching, abrasions)Caused by mechanical means (scratching, abrasions)

Excoriation

Ulcer Craterlike lesion caused by disintegration of the skinCraterlike lesion caused by disintegration of the skin Pressure-relatedPressure-related

Ulcer

Bed Sore

Fissure Linear crack or break from epidermis to dermisLinear crack or break from epidermis to dermis Caused by dry skinCaused by dry skin

Fissures

Burns Classified according to severityClassified according to severity Infection most important threat; leading cause of deathInfection most important threat; leading cause of death Rule of NinesRule of Nines  Estimates volume of fluid loss  Determines how much body surface is burned  Body divided into 11 areas (each 9% of body)  1% area surrounding genitals

First Degree Burn Epidermis onlyEpidermis only

First Degree Burn

Second Degree Burn Deeper layers of epidermisDeeper layers of epidermis Blisters possibleBlisters possible Very painful – exposed nerve endingsVery painful – exposed nerve endings

Second Degree Burn

Third Degree Burn Complete destruction of the epidermisComplete destruction of the epidermis May extend into dermisMay extend into dermis

Third Degree Burn Nerve endings destroyed – not painful (initially)Nerve endings destroyed – not painful (initially)

Third Degree Burns

Third Degree Becomes painful w/ regenerationBecomes painful w/ regeneration Skin grafts neededSkin grafts needed

Skin graft donor site: about halfway through the initial healing stage

Skin Cancer A B C D for cancerA B C D for cancer A = AsymmetryA = Asymmetry  Are all sides the same? B = BorderB = Border  Is the border smooth? C = ColorC = Color  Are there areas of different color? D = DiameterD = Diameter  Larger than a pencil eraser?

Basal Cell Carcinoma Most CommonMost Common Stratum Basale cells involvedStratum Basale cells involved Appear on sun exposed areas of faceAppear on sun exposed areas of face Slow growingSlow growing 99% cure rate99% cure rate

Squamous Cell Carcinoma Stratum Spinosum cells involvedStratum Spinosum cells involved Appears on scalp, ears, dorsum of hands, lower lipAppears on scalp, ears, dorsum of hands, lower lip Fast growingFast growing Metastasizes to surroundingMetastasizes to surrounding lymph nodes lymph nodes High cure rate w/ early detectionHigh cure rate w/ early detection

Malignant Melanoma 5% of all cancers5% of all cancers DNA of melanocytes damagedDNA of melanocytes damaged Metastasizes rapidly to lymph nodesMetastasizes rapidly to lymph nodes and blood vessels and blood vessels 50% survival rate50% survival rate