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EPITHELIAL TISSUEEPITHELIAL TISSUE
CONNECTIVE TISSUECONNECTIVE TISSUE
MUSCULAR TISSUEMUSCULAR TISSUE
NERVOUS TISSUENERVOUS TISSUE
Oral cavity
Skin
Digestive Tract
Peritoneum
Respiratory Passages
Pleural cavities
Hart andBlood vessels
Pericardium
Urinary tracts
Glands
Limph vessels
FUNCTIONS OF EPITHELIAFUNCTIONS OF EPITHELIA
COVERING EPITHELIACOVERING EPITHELIA
covering of surfaces and lining of cavitiescovering of surfaces and lining of cavities
protection protection of covered tissueof covered tissue
absorption absorption -- intestines, proximal tubules of kidneyintestines, proximal tubules of kidney
GLANDULAR EPITHELIAGLANDULAR EPITHELIA
secretionsecretion - exocrine glands - exocrine glands
NEUROEPITHELIAL CELLSNEUROEPITHELIAL CELLS
sensation sensation - olfactory epithelium , taste buds - olfactory epithelium , taste buds
MYOEPITHELIAL CELLSMYOEPITHELIAL CELLS
contractility contractility -- salivary glands, sweat glands salivary glands, sweat glands
COMPONENTS OF BASAL COMPONENTS OF BASAL LAMINALAMINA
� COLLAGEN TYPE IVCOLLAGEN TYPE IV
� LAMININ, FIBRONECTIN LAMININ, FIBRONECTIN
(glycoproteins)(glycoproteins)
� PROTEOGLYCANSPROTEOGLYCANS - -
(HEPARAN SULFATE)(HEPARAN SULFATE)
� ANCHORING FIBRILS ANCHORING FIBRILS --
COLLAGEN TYPE VIICOLLAGEN TYPE VII
FUNCTIONS OF BASAL FUNCTIONS OF BASAL LAMINALAMINA
Selective barrier between connective tissue Selective barrier between connective tissue
and epitheliumand epithelium
Adhesion of the connective tissue and Adhesion of the connective tissue and
the epitheliumthe epithelium
POLARITY OF EPITHELIAPOLARITY OF EPITHELIA
APICAL SURFACE APICAL SURFACE
BASAL SURFACE - rests on basal laminaBASAL SURFACE - rests on basal lamina
TYPES OF EPITHELIATYPES OF EPITHELIA
ACCORDING TO NUMBER OF LAYERSACCORDING TO NUMBER OF LAYERS
simplesimple
stratifiedstratified
pseudostratifiedpseudostratified
ACCORDING TO SHAPE OF CELLSACCORDING TO SHAPE OF CELLS
squamoussquamous
cuboidalcuboidal
columnarcolumnar
SIMPLE SQUAMOUS EPITHELIUM SIMPLE SQUAMOUS EPITHELIUM
endothelium, mesotheliumendothelium, mesothelium
SIMPLE CUBOIDAL EPITHELIUM SIMPLE CUBOIDAL EPITHELIUM
proximal and distal renal tubulesproximal and distal renal tubules
SIMPLE COLUMNAR EPITHELIUM SIMPLE COLUMNAR EPITHELIUM
stomach, small and large intestine, stomach, small and large intestine, oviductoviduct
PSEUDOSTRATIFIED EPITHELIUM PSEUDOSTRATIFIED EPITHELIUM
respiratory passages, epididymisrespiratory passages, epididymis
STRATIFIED SQUAMOUS EPITHELIUM STRATIFIED SQUAMOUS EPITHELIUM
keratinised - skinkeratinised - skin
nonkeratinised - oral cavity, vaginanonkeratinised - oral cavity, vagina
STRATIFIED SQUAMOUS EPITHELIUMSTRATIFIED SQUAMOUS EPITHELIUM
keratinisedkeratinised nonkeratinisednonkeratinised
Skin Cornea Esophagus
INTERCELLULAR INTERCELLULAR JUNCTIONSJUNCTIONS
membrane associated structures responsible membrane associated structures responsible for cohesion and communication between for cohesion and communication between cellscells
ADHERING JUNCTIONSADHERING JUNCTIONS
IMPERMEABLE JUNCTIONSIMPERMEABLE JUNCTIONS
COMMUNICATING JUNCTIONSCOMMUNICATING JUNCTIONS
TIGHT JUNCTION - TIGHT JUNCTION - ZONULA OCCLUDENSZONULA OCCLUDENS
LOCATION - the most apicalLOCATION - the most apical
SHAPE - band encircling the cellSHAPE - band encircling the cell
MORPHOLOGY - network of linear fusion MORPHOLOGY - network of linear fusion
sites between membrane associated proteinssites between membrane associated proteins
FUNCTION - close off the intercellular space FUNCTION - close off the intercellular space
(leakiness of the epithelium)(leakiness of the epithelium)
TIGHT JUNCTION - TIGHT JUNCTION - ZONULA ZONULA
OCCLUDENSOCCLUDENS
Preventthe flowbetween the cells
Prevent the movement of membrane proteins
DESMOSOME -DESMOSOME -MACULA ADHERENSMACULA ADHERENS
LOCATION - along the lateral membranesLOCATION - along the lateral membranes
DISK-SHAPED DISK-SHAPED
MORPHOLOGY -MORPHOLOGY -
attachment plaques - desmoplaquinattachment plaques - desmoplaquin
intercellular space - desmogleinintercellular space - desmoglein
cytokeratin filaments cytokeratin filaments
FUNCTION - very firm adhesion of FUNCTION - very firm adhesion of neighbor-cellsneighbor-cells
ZONULA ADHERENSZONULA ADHERENSLOCATION - just below tight junctionLOCATION - just below tight junction
SHAPE - band encircling the cellSHAPE - band encircling the cell
MORPHOLOGY -MORPHOLOGY -
dense plagues - dense plagues - αα -actinin, vinculin, -actinin, vinculin, myosin, tropomyosinmyosin, tropomyosin
intercellular space - E-kadherin and intercellular space - E-kadherin and calcium ionscalcium ions
actin-containing microfilamentsactin-containing microfilaments
FUNCTION - adhesion of neighbor-cellsFUNCTION - adhesion of neighbor-cells
HEMIDESMOSOMEHEMIDESMOSOME
LOCATION - contact zone LOCATION - contact zone
between epithelium and basal between epithelium and basal
laminalamina
DISK-SHAPEDDISK-SHAPED
MORPHOLOGY - half a MORPHOLOGY - half a
desmosomedesmosome
FUNCTION - binds the epithelial FUNCTION - binds the epithelial
cell to basal laminacell to basal lamina
GAP JUNCTION -GAP JUNCTION -NEXUS NEXUS
LOCATION - anywhere along the lateral LOCATION - anywhere along the lateral membranes of epithelial cellsmembranes of epithelial cells
MORPHOLOGY - hexamers of proteins MORPHOLOGY - hexamers of proteins with a hydrophilic pore in the center with a hydrophilic pore in the center (connexon)(connexon)
FUNCTION - interchange of small FUNCTION - interchange of small molecules between adjacent cells (cyclic molecules between adjacent cells (cyclic AMP, ions) AMP, ions)
MICROVILLIMICROVILLI
Extension of cytoplasm - Extension of cytoplasm -
11µµ m longm long
Actin-containing Actin-containing
microfilamentsmicrofilaments
FUNCTION - increase FUNCTION - increase
the surface areathe surface area
LIGHT MICROSCOPE LIGHT MICROSCOPE
- BRUSH BORDER - BRUSH BORDER
CILIACILIA
LONG PROJECTIONS - 10 LONG PROJECTIONS - 10 µµmm
MOTILEMOTILE
STRUCTURE:STRUCTURE:
central pair of microtubulscentral pair of microtubuls
9 pairs at the periphery9 pairs at the periphery
INSERTED INTO BASAL BODIESINSERTED INTO BASAL BODIES
FUNCTION - permit a current of FUNCTION - permit a current of material over epitheliummaterial over epithelium
STEREOCILIA - STEREOCILIA - long microvillilong microvilli
FLAGELLA - FLAGELLA - similar in structure to ciliasimilar in structure to cilia
GLANDULAR GLANDULAR EPITHELIA - GlandsEPITHELIA - Glands FUNCTION - FUNCTION -
secretion of secretion of
products which are products which are
used in other parts used in other parts
of the organismof the organism
SEROUS GLANDSSEROUS GLANDSACINAR SECRETORY PORTIONSACINAR SECRETORY PORTIONS
SECRET CLEAR FLUID SECRETIONSECRET CLEAR FLUID SECRETION
SEROUS CELLS:SEROUS CELLS:
ruonded nucleus at basal part of ruonded nucleus at basal part of
cytoplasm cytoplasm
abundant RER – abundant RER –
basophilic cytoplasmbasophilic cytoplasm
well visible secretory well visible secretory
granules at the apexgranules at the apex
MUCOUS GLANDSMUCOUS GLANDSTUBULAR SECRETORY TUBULAR SECRETORY
PORTIONSPORTIONS
SECRET MUCUSSECRET MUCUS
MUCOUS CELLSMUCOUS CELLS
� flat nucleus at flat nucleus at
the basisthe basis
� large, translucent large, translucent
secretory granulessecretory granules
� well developed well developed
Golgi complexGolgi complex
TYPES OF EXOCRINE GLANDSTYPES OF EXOCRINE GLANDS
APOCRINEsecretory product is discharged with apical part of cytoplasm
MEROCRINEsecretory granules leave the cell by exocytosis
HOLOCRINEsecretory product is shed with whole cell
NUTRITION OF EPITHELIANUTRITION OF EPITHELIA
NO BLOOD VESSELS IN EPITHELIANO BLOOD VESSELS IN EPITHELIA
NUTRIENTS AND PRECURSORS OF NUTRIENTS AND PRECURSORS OF PRODUCTS DIFFUSE FROM PRODUCTS DIFFUSE FROM CONNECTIVE TISSUE ACROSS THE CONNECTIVE TISSUE ACROSS THE BASAL LAMINA TO EPITHELIAL CELLSBASAL LAMINA TO EPITHELIAL CELLS