chapter 05 histology: epithelium -
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CHAPTER 05
ANATOMY & PHYSIOLOGY IBIO 211:
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Dr. Lawrence G. Altmanwww.lawrencegaltman.comSome illustrations are courtesy of McGraw-Hill.
Histology:EPITHELIUMPart 01: Brief IntroductionPart 02: Survey of Types
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TISSUES Group of cells closely associated in:a) structure (similar)b) function (common or related)
HISTOLOGY = the study of tissues
TYPES In general, FOUR (4) MAJOR TYPES:
1. EPITHELIAL (this week's topic)2. CONNECTIVE (supportive)3. MUSCLE (movement)4. NERVOUS (control)
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4EPITHELIALOCATIONS:
COVERING or LINING EPITHELIUM of-
a) FREE SURFACES (i.e. SKIN)
b) LINING of OPEN CAVITIES (i.e. DIGESTIVE, RESPIRATORY SYSTEMS)
c) LINING of CLOSED CAVITIES (i.e. VENTRAL BODY CAVITY)
d) LINING of BLOOD VESSELS and HEARTMay also serve as a GLANDULAR EPITHELIUMTo be discussed…
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5EPITHELIAMANY FUNCTIONS
PROTECTION Bacterial Infections, Injury etc
ABSORPTION Example: lining of digestive tract
FILTRATION Example: Renal (renal = kidney)
SECRETION Example: glandular epithelium
…or any COMBINATION of the above.
6EPITHELIAL FEATURES
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7EPITHELIAL FEATURESPOLARITY
APICAL surface: often contain MICROVILLI:highly folded EXTENSIONSof the PLASMA MEMBRANEIncreases ABSORBTION areaNote: “brush border” = many microvilli
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9EPITHELIAL FEATURESPOLARITY
BASAL surface: bottom - most layer of epithelialtissue is always attached to aBASEMENT MEMBRANE.Acts as a barrier between the EPITHELIUMand the underlying CONNECTIVE ISSUE.
BASEMENTMEMBRANE
EPITHELIUM
10EPITHELIAL FEATURESPOLARITY
BASAL surface: The BASEMENT MEMBRANEis composed of two layers.Closest to the epitheliumActually secreted by the epithelium.
BASALLAMINA
- thin, non - cellular adhesive layer- selective filter of materials from blood- template for wound repair
Below the BASAL LAMINAExtracellular network of collagen fibers
RETICULARLAMINABASAL LAMINA + RETICULAR LAMINA = BASEMENT MEMBRANE
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11EPITHELIAL FEATURES
12EPITHELIAL FEATURES
AVASCULARITY - No blood vessels
- Nutrients etc. via DIFFUSION(upward)
- IS innervated
REGENERATION - High MITOTIC INDEX (turnover)
END of PART 01: Brief Introduction
NEXT: Part 02: Survey of Types
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13EPITHELIA: SURVEY of TYPES
CLASSIFICATION of EPITHELIA
Number!ofLayers
SIMPLE epithelium:one layer of cells
cells
BM
BM
STRATIFIED epithelium:multiple layers of cells
SHAPE
of!cells
SQUAMOUS flattenedCUBOIDAL! height!=!widthCOLUMNAR! height!>!width!
STRATIFIED EPITHELIUM: layers may have DIFFERENT SHAPES butnomenclature based upon the CELL SHAPE of the free (APICAL) surface.
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SIMPLE epithelium:Little protection; other functions
in!other!words,ALL!of!the!shapes!may!exist!in!theone!cell!layer!arrangement!
LOOKS!stratifiedbut!really!NOT!
ONE!LAYER!of!cellsbut!different!heights
PSEUDOSTRATIFIEDPSEUDO!=!FALSE!or!FAKE
TYPES:
SIMPLE!SQUAMOUS
SIMPLE!CUBOIDAL
SIMPLE!COLUMNAR
TYPES
EPITHELIA: SURVEY of TYPES
CLASSIFICATION of EPITHELIA
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SIMPLE epithelium:Little protection; other functions
FLATTENEDSINGLE!LAYER
usually!quite!permeable
In!certain!locations-!special!names:
ENDOTHELIUM:! LINING!of!BLOOD! VESSELS/CAPILLARIES
MESOTHELIUM: SEROSAL!MEMBRANES
KIDNEY:!
FILTRATION
LUNGS:!
DIFFUSION
SIMPLE!SQUAMOUS!EPITHELIUM!
TYPES:
SIMPLE!SQUAMOUS
SIMPLE!CUBOIDAL
SIMPLE!COLUMNAR
PSEUDOSTRATIFIEDPSEUDO!=!FALSE!or!FAKE
TYPESEPITHELIA: SURVEY of TYPES
CLASSIFICATION of EPITHELIA
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SIMPLE epithelium:Little protection; other functions
ALVEOLUS!(LUNG)LAB!ATLASPLATE!85-D
BOWMAN'S!CAPSULE!(KIDNEY)LAB!ATLASPLATE!97-D
Also see:
TYPES:
SIMPLE!SQUAMOUS
SIMPLE!CUBOIDAL
SIMPLE!COLUMNAR
PSEUDOSTRATIFIEDPSEUDO!=!FALSE!or!FAKE
TYPESEPITHELIA: SURVEY of TYPES
CLASSIFICATION of EPITHELIA
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SIMPLE epithelium:Little protection; other functions
TYPES:
SIMPLE!SQUAMOUS
SIMPLE!CUBOIDAL
SIMPLE!COLUMNAR
PSEUDOSTRATIFIEDPSEUDO!=!FALSE!or!FAKE
TYPES
usually!quite!permeable
DISTAL!TUBULE!(KIDNEY)Lab!Atlas:!PLATE!9-F
KIDNEY:!ABSORPTION(Many!MICROVILLI)
Also see:
EPITHELIA: SURVEY of TYPES
CLASSIFICATION of EPITHELIA
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SIMPLE epithelium:Little protection; other functions
BOTH!TYPES:GOBLET!CELLSMAY!BE!PRESENT
(MUCOUS!PRODUCTION)
NOCILIA
EXAMPLE:DIGESTIVE!TRACT(STOMACH!to!ANUS)
TYPES:
SIMPLE!SQUAMOUS
SIMPLE!CUBOIDAL
SIMPLE!COLUMNAR
PSEUDOSTRATIFIEDPSEUDO!=!FALSE!or!FAKE
TYPES
CILIATED
EXAMPLE:
UTERINE!TUBES
EPITHELIA: SURVEY of TYPES
CLASSIFICATION of EPITHELIA
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SIMPLE epitheliumLittle protection; other functions
TYPES:
SIMPLE!SQUAMOUS
SIMPLE!CUBOIDAL
SIMPLE!COLUMNAR
PSEUDOSTRATIFIEDPSEUDO!=!FALSE!or!FAKE
TYPESEPITHELIA: SURVEY of TYPES
CLASSIFICATION of EPITHELIA
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SIMPLE epithelium:Little protection; other functions
TYPES:
SIMPLE!SQUAMOUS
SIMPLE!CUBOIDAL
SIMPLE!COLUMNAR
PSEUDOSTRATIFIEDPSEUDO!=!FALSE!or!FAKE
TYPES
MAYHAVECILIAEXAMPLE:RESPIRATORYTRACT
REALLY!SIMPLE!EPITHELIUM!!!!!
why???-ALL!CELLS!REST!ON!BM-SOME!DO!NOT!REACH!APICAL!SERVICE
-NUCLEI!AT!DIFFERENT!LEVELS!GIVING!
FALSE!APPEARANCE!of!BEING!STRATIFIED
EPITHELIA: SURVEY of TYPES
CLASSIFICATION of EPITHELIA
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SIMPLE epithelium:Little protection; other functions
TYPES:
SIMPLE!SQUAMOUS
SIMPLE!CUBOIDAL
SIMPLE!COLUMNAR
PSEUDOSTRATIFIEDPSEUDO!=!FALSE!or!FAKE
TYPESEPITHELIA: SURVEY of TYPES
CLASSIFICATION of EPITHELIA
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SIMPLE epithelium:Little protection; other functions
TYPES:
SIMPLE!SQUAMOUS
SIMPLE!CUBOIDAL
SIMPLE!COLUMNAR
PSEUDOSTRATIFIEDPSEUDO!=!FALSE!or!FAKE
TYPESEPITHELIA: SURVEY of TYPES
CLASSIFICATION of EPITHELIA
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STRATIFIED!epithelium:Different!layers!may!have!
different!shapesBUT
nomenclature:!
BASED!ON!CELL!SHAPEof!the
free!(APICAL)!surface
STRATIFIED!SQUAMOUS!EPITHELIUM!
MOST!COMMON!TYPE
of!STRATIFIED!EPITHELIUM-PROTECTION!vs.!ABRASION
-HIGH!MITOTIC!INDEX
-CELLS!SHED!
FROM!APICAL!REGION
BASAL!LAYERS:
-USUALLY!NOT!SQUAMOUS
-SITE!OF!NEW!CELL!
GENERATION
APICAL:!!MAY!POSSESS
KERATIN!=!
WATER!INSOLUBLE!PROTEIN
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25STRATIFIED!SQUAMOUS!EPITHELIUM!
26STRATIFIED!COLUMNAR!EPITHELIUM!
REMINDER:STRATIFIEDEPITHELIUMNAMEDONBASISofAPICALLAYER
VERY!RARE!
-URETHRA!of!MALE
-some!LARGE!DUCTS!of!GLANDS!
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27STRATIFIED!CUBOIDAL!EPITHELIUM!
ALSO!VERY!RARE!
-2!to!3!CELLS!DEEP
-LARGEST!DUCTS!of:!
SWEAT!GLANDS!
MAMMARY!GLANDS
SALIVARY!GLANDS
SURROUNDING!EGGS
28TRANSITIONAL!EPITHELIUM!
RELAXED DISTENDED
CUBOIDAL
COLUMNAR
"UMBRELLACELLS"
THINK
URINARY
BLADDER!!
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29TRANSITIONAL!EPITHELIUM!
Bladder
PICTURE!EQUIVALENT:ATLAS:!
Fig.!11-B!(RELAXED)Fig.!11-C!(DISTENDED)
30TRANSITIONAL!EPITHELIUM!
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