1. Tissue IntroductionTissue Introduction
&&
Epithelial TissueEpithelial Tissue
PhysiologyPhysiology

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. 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. 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. 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. 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. 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

9. 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

11. 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

13. 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

14. Cilia
Basement
Membrane

15. 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

16. Keratin
Stratified
Cubodial (layers
of cubodial only)

17. 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

19. 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.

20. 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

22. 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