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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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