Epithelialtissue 120208062655-phpapp02


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Epithelialtissue 120208062655-phpapp02

  1. 1. Tissue IntroductionTissue Introduction && Epithelial TissueEpithelial Tissue PhysiologyPhysiology
  2. 2. Cells to TissuesCells to Tissues  As human body develops from singleAs human body develops from single to multicellular, cells specialize.to multicellular, cells specialize.  Body is interdependent system,Body is interdependent system, malfunction of one group of cells ismalfunction of one group of cells is catastrophic.catastrophic.  Cells specialize into types of tissues,Cells specialize into types of tissues, then interspersed into organs.then interspersed into organs.
  3. 3. Tissues = groups of cells that areTissues = groups of cells that are similar in structure and function.similar in structure and function.  EpitheliumEpithelium  CoveringsCoverings  Linings of surfacesLinings of surfaces  ConnectiveConnective  SupportSupport  Bone, ligaments,Bone, ligaments, fatfat  MuscleMuscle  MovementMovement  NervousNervous  ControlControl  Brain, nerves,Brain, nerves, spinal cordspinal cord
  4. 4. Function of Epithelial TissueFunction of Epithelial Tissue  ProtectionProtection  Skin protects from sunlight & bacteria & physicalSkin protects from sunlight & bacteria & physical damage.damage.  AbsorptionAbsorption  Lining of small intestine, absorbing nutrients intoLining of small intestine, absorbing nutrients into bloodblood  FiltrationFiltration  Lining of Kidney tubules filtering wastes from bloodLining of Kidney tubules filtering wastes from blood plasmaplasma  SecretionSecretion  Different glands produce perspiration, oil, digestiveDifferent glands produce perspiration, oil, digestive enzymes and mucusenzymes and mucus
  5. 5. Characteristics of Epithelial TissueCharacteristics of Epithelial Tissue  Form continuous sheets (fit like tiles)Form continuous sheets (fit like tiles)  Apical SurfaceApical Surface  All epithelial cells have a top surface thatAll epithelial cells have a top surface that borders an open space – known as aborders an open space – known as a lumenlumen  Basement MembraneBasement Membrane  Underside ofUnderside of allall epithelial cells which anchorsepithelial cells which anchors them to connective tissuethem to connective tissue  Avascularity (a = without)Avascularity (a = without)  Lacks blood vesselsLacks blood vessels  Nourished by connective tissueNourished by connective tissue  Regenerate & repair quicklyRegenerate & repair quickly
  6. 6. Classification ofClassification of Epithelial TissueEpithelial Tissue  Cell ShapeCell Shape  Squamous – flattened likeSquamous – flattened like fish scalesfish scales  Cuboidal - cubesCuboidal - cubes  Columnar - columnsColumnar - columns  Cell LayersCell Layers  Simple (one layer)Simple (one layer)  Stratified (many layers)Stratified (many layers)  Named for the type of cell atNamed for the type of cell at the apical surface.the apical surface.
  7. 7. Simple Squamous EpitheliumSimple Squamous Epithelium  StructureStructure  Single Layer of flattened cellsSingle Layer of flattened cells  FunctionFunction  Absorption, and filtrationAbsorption, and filtration  Not effective protection – single layer of cells.Not effective protection – single layer of cells.  LocationLocation  Walls of capillaries, air sacs in lungsWalls of capillaries, air sacs in lungs  Form serous membranes in body cavityForm serous membranes in body cavity
  8. 8. Simple Cuboidal EpitheliumSimple Cuboidal Epithelium  StructureStructure  Single layer of cube shaped cellsSingle layer of cube shaped cells  FunctionFunction  Secretion and transportation in glands,Secretion and transportation in glands, filtration in kidneysfiltration in kidneys  LocationLocation  Glands and ducts (pancreas & salivary),Glands and ducts (pancreas & salivary), kidney tubules, covers ovarieskidney tubules, covers ovaries
  9. 9. Simple Columnar EpitheliumSimple Columnar Epithelium  StructureStructure  Elongated layer of cells with nuclei at same levelElongated layer of cells with nuclei at same level  FunctionFunction  Absorption, Protection & SecretionAbsorption, Protection & Secretion  When open to body cavities – called mucousWhen open to body cavities – called mucous membranesmembranes  Special FeaturesSpecial Features  MicrovillMicrovilli, bumpy extension of apical surface, increasei, bumpy extension of apical surface, increase surface area and absorption rate.surface area and absorption rate.  Goblet cellsGoblet cells, single cell glands, produce protective, single cell glands, produce protective mucus.mucus.  LocationLocation  Linings of entire digestive tractLinings of entire digestive tract
  10. 10. Pseudostratified EpitheliumPseudostratified Epithelium  StructureStructure  Irregularly shaped cells with nuclei at differentIrregularly shaped cells with nuclei at different levels – appear stratified, but aren’t.levels – appear stratified, but aren’t.  All cells reach basement membraneAll cells reach basement membrane  FunctionFunction  Absorption and SecretionAbsorption and Secretion  Goblet cells produce mucusGoblet cells produce mucus  Cilia (larger than microvilli) sweep mucusCilia (larger than microvilli) sweep mucus  LocationLocation  Respiratory Linings & Reproductive tractRespiratory Linings & Reproductive tract
  11. 11. Cilia Basement Membrane
  12. 12. Stratified Squamous EpitheliumStratified Squamous Epithelium  StructureStructure  Many layers (usually cubodial/columnar atMany layers (usually cubodial/columnar at bottom and squamous at top)bottom and squamous at top)  FunctionFunction  ProtectionProtection  Keratin (protein) is accumulated in older cellsKeratin (protein) is accumulated in older cells near the surface – waterproofs and toughensnear the surface – waterproofs and toughens skin.skin.  LocationLocation  Skin (keratinized), mouth & throatSkin (keratinized), mouth & throat
  13. 13. Keratin Stratified Cubodial (layers of cubodial only)
  14. 14. Transitional EpitheliumTransitional Epithelium  StructureStructure  Many layersMany layers  Very specialized – cells at base are cuboidalVery specialized – cells at base are cuboidal or columnar, at surface will vary.or columnar, at surface will vary.  Change between stratified & simple as tissueChange between stratified & simple as tissue is stretched out.is stretched out.  FunctionFunction  Allows stretching (change size)Allows stretching (change size)  LocationLocation  Urinary bladder, ureters & urethraUrinary bladder, ureters & urethra
  15. 15. GlandsGlands  One or more cells that make and secrete aOne or more cells that make and secrete a product.product.  Secretion = protein in aqueous solution:Secretion = protein in aqueous solution: hormones, acids, oils.hormones, acids, oils.  Endocrine glandsEndocrine glands  No duct, release secretion into blood vesselsNo duct, release secretion into blood vessels  Often hormonesOften hormones  Thyroid, adrenal and pituitary glandsThyroid, adrenal and pituitary glands  Exocrine glandsExocrine glands  Contain ducts, empty onto epithelial surfaceContain ducts, empty onto epithelial surface  Sweat, Oil glands, Salivary glands, Mammary glands.Sweat, Oil glands, Salivary glands, Mammary glands.
  16. 16. Shapes of Exocrine glandsShapes of Exocrine glands Branching  Simple – single, unbranched duct  Compound – branched. Shape: tubular or alveolar  Tubular – shaped like a tube  Alveolar – shaped like flasks or sacs  Tubuloalveolar – has both tubes and sacs in gland
  17. 17. Modes of SecretionModes of Secretion  (How the gland’s product is released)(How the gland’s product is released)  MerocrineMerocrine  Just released by exocytosis without alteringJust released by exocytosis without altering the gland at all.the gland at all.  Ex: Sweat glands and salivary glandsEx: Sweat glands and salivary glands  HolocrineHolocrine  The gland ruptures and releases secretionThe gland ruptures and releases secretion and dead cells as well.and dead cells as well.  Sebaceous (oil glands on the face) onlySebaceous (oil glands on the face) only exampleexample