Lecture # 3. SURFACE EPITHELIA Epithelia Closely apposed cells No or limited intercellular substances _____________ _____________ Derived from 3 germ layers: ____________ ____________- skin ____________ ____________ - inner lining lining of blood vessels vessels ____________ ____________ - inner lining lining of te !" tract tract pitelial tissues rest on connective tissues ________________ ________________ – CT underneath digestive$ respiratory respiratory lining epitelia. - - - - - - - - - - - - - - - - -
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pitelial e"posure to #i$erent matters: matters: !ases-integumentary !ases-integumentary 6 respiratory7 respiratory7 Li5uids-circulatory Li5uids-circulatory 6 urinary7 8emisolids-!" 8emisolids-!" tract - - - - - - - - - - - - - - - - –
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__________________ ____________________ __ % underlying underlying support &ere &ere epitelial cells are rested. "t demarcates te underlying C' from epitelium. - - - - - - - - - - - - - - - - Basement membrane composition _________________ _________________ - (embrane proteins proteins of te epitelial epitelial cells are ancored in te basal lamina. 'e ma)or * glycoprote glycoproteins ins - ___________ ___________ and 'ype "+ C,LL!N /N: acts as a selective$ permeable permeable 0lter bet&een epitelium and connective tissue 1C'2. _________________ _________________ - eticular eticular 0bers embedded embedded in ground ground substance tat connect te basal lamina &it te underlying C'. "t is syntesi4ed by cells of te C'. - - - - - - - - - - - - - - - - Functions of Epithelia: Absorption Absorption - ___________ Secretion - _________ Sensation Sensation - gustative and olfactory neuroepitelium Contractilit Contractilit - _____________ cells % breast !!!!!!!!!!!!! 5uickly &en sub)ected to trauma 6 destruction. •
% Tpes of Epithelia 9. Cover Cover or line all body body surfaces$ surfaces$ caviti cavities es and tubes tubes - !!!!!!!!!!!!!!!!!!!! *. pitelium tat is primarily involved in secretion secretion is often arranged into structures called glands. - !!!!!!!!!!!!!!!!!!!!! - - - - - - - - - - - - - - - - Surface Epithelia are reco&ni'e# base# on ( morpholo&ical characteristics: characteristics: 9. Number Number of of cell cell layers layers _________________ __________________ _ _________________ _________________ *. 8ape 8ape of te componen componentt cells cells _______________ _______________ _________________ _________________ ________________ ________________ 3. resen resence ce of surface surface modi0c modi0catio ations: ns: _______________ _______________ _________________ _________________ ________________ ________________ _______________ _______________ - - - - - - - - - - - - - - - - -
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)o#i*cations on the Apical surface of epithelial cells +, )icr )icro-i o-ill llii ingerlike process tat protrude from te cells apical surface -(. _______________ _______________ or ________ or _____________ _____ in in L( 10ne vertical lines on cell surface2 'o 'o increase increase surface area area of absorption. absorption. articularly numerous in te intestinal mucosa. Core : consist of __________0lament •
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maintains te ?uid nature of ?o&ing blood triggers _________________ &en needed cell adesion transmits in?ammatory signals permit normal arterial dilatation 34itric o"i#e5a pri'e6innin& molecule in +789 r, Robert Furch&ott of the State Uni-ersit of 4e6 ;or< 6as a6ar#e# a 4obel Pri'e for )e#icine "denti0ed te factor produced by te endotelium governing ______________ 1endoteliumderived rela;ation factor$@ or D2 as =Nitric o;ide> a signaling molecule for many processes and te single most po&erful artery dilating agent kno&n. - - - - - - - - - - - - - - - - •
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%, Cilia ./inocila0 ingerlike e;tensions resent in cells speciali4ed for _____________________________ over te surface of te epitelium. Cilia are motile % beat se5uentially or syncronously in one direction. Core : microtubules tat comprise te a;oneme. • •
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/arta&ener1s sn#rome % inerited abnormality in cilia$ compromising respiratory functions$ &it ine of te inner ear.
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!!!!!!!!!!!!!!!!!: Lining of te pleural$ pericardial and peritoneal cavities
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- - - - - - - - - - - - - - - - Classi*cation of Epithelia:
S2uamous Epithelium lining surfaces involved in passive transport 1di
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En#othelium: inner lining of blood vessels. Importance of en#othelium:
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Simple Cuboi#al lines _________ ducts and tubules tat may ave e;cretory$ secretory or absorptive functions. ;. collecting tubules of te kidney and te small e;cretory ducts of te salivary glands and pancreas. - - - - - - - - - - - - - - - - •
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Simple Columnar cells are taller and appear columnar nuclei are elongated7 basal$ central$ or apical most often found on _____________ surfaces suc as in te small intestine. it may constitute te lining of _____________surfaces suc as tat of te stomac. - - - - - - - - - - - - - - - - •
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Simple columnar epithelium )o#i*cations: 4on=ciliate# tpe - 9 Layer of rectangular cells$ often containing goblet cells7 .>0!!!!!!!!!!!! ,rgan: !" tract 1stomac to anus2$ ducts of glands and gallbladder ;n: 8ecretion and bsorption Ciliate# tpe % 1A2_______ ,rgan: parts of upper resp. tract$ uterine tubes$ uterus$ central canal of spinal cord ;n: (oves ?uids B particles along passage&ays - - - - - - - - - - - - - - - - 8imple columnar: non%ciliated - for absorption B secretion.
'e cilia propel mucus &it entrapped particles to&ards te paryn;. = = = = = = = = = = = = = = = = =
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8imple Columnar ciliated ound mainly in female reproductive tract allopian tube B uterine tube Ciliary action facilitates transport of te _______________ from te ovary to te uterus. = = = = = = = = = = = = = = = = = Pseu#ostrati*e# ______________ of simple columnar epitelium. 'e appearance in section conveys te _______________ impression tat tere is more tan one layer of cells. ll te cells rest on te basement membrane. lmost e;clusively con0ned to te larger air&ays of te respiratory system. = = = = = = = = = = = = = = = = = )ucociliar escalator (ucus secreted by goblet cells are converyed on te surface. (ucus traps _________________ material •
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Strati*e# Epithelia epitelia consisting of t&o or more layers of cells. function mainly for !!!!!!!!!!!!!! . te degree and nature of te strati0cation are related to te kinds of pysical stresses to &ic te surface is e;posed N,': strati0ed epitelium is classi0ed on te basis of te sape of te cells in te ______ L ,NL - - - - - - - - - - - - - - - - Strati*e# S2uamous _________________________ ;ample: skin epidermis 8trati0ed 85uamous _________________________ ;ample : sopagus ,ter e;amples: ______________________________________ = = = = = = = = = = = = = = = = = Strati*e# cuboi#al *E layers of cuboid cells ,rgans: Ducts of s&eat glands$ male uretra ;n: rotection = = = = = = = = = = = = = = = = = Strati*e# columnar epithelium (any _____________ cell layers % columnar cells in super0cial layer ,rgan: Lines part of uretra$ e;cretory ducts of glands$ anal mucous membrane ;n: rotection and ________________ = = = = = = = = = = = = = = = = = Transitional Epithelium ______________ appearance % cuboid to s5uamous ,rgans: exclusively in e;cretory urinary passages 1renal calyces and pelvis$ ureter$ urinar bla##er$ and part of te uretra2. •
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;n: ermits ___________________ = = = = = = = = = = = = = = = = = Frinary bladder - Gigly specialised to accommodate a great degree of ___________ and to &itstand te ___________ of urine. •
beneat te luminal surface of simple columnar epitelium = = = = = = = = = = = = = = = = = A#herens "n, Donula a#herens lso called =belt desmosome> Located )ust belo& tigtBoccluding );n. orms a band tat completely encircles eac epit. cells. Cell membranes of ad)oining cells are very close but neiter adere nor fuse. 8eparated by an intercellular space 19I-*J nm &ide2 articularly present in epitelia &it microvilli or cilia •
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Rela"e# vs isten#e# )o#i*cations on the lateral surfaces of epithelial cells, Cell Junctions / Intercellular jxns. / Junctional complexes bind epitelial cells to ad)acent cells to provide pysical strengt and mediate e;cange of information and metabolites. 'e intimate contact bet&een epiteiial cells ensures tat materials passing troug te epitelium ave to pass troug te cells$ rater tan bet&een tem. = = = = = = = = = = = = = = = = = Cell ?unctions +, !!!!!!!!!!!!!!!!!!!!!!! %, !!!!!!!!!!!!!!!!!!!!!!! (, !!!!!!!!!!!!!!!!!!!!!!! @, !!!!!!!!!!!!!!!!!!!!!!! •
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Ti&ht unction or cclu#in& unction =occlude> % to block B inder (ost apically situated of te )unctional comple;es a continuous belt-like )unction 4onula H latin for belt 7 =4onula occludens> roteins in te membrane of ad)acent cells called occludin interact &it eac oter to produce tis tigt seal. to seal te intercellular spaces so tat luminal contents cannot penetrate bet&een te lining cells. Common in transport epithelia. ;ample: •
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= = = = = = = = = = = = = = = = = Spot esmosome Fsually situated )ust belo& 4onula aderens. 'ey do not form a band around te epitelial cells 1instead2 button-like or rivet-like adesions tat are arranged in a line t te desmosome );n$ te cells are separated by a relatively &ide intercellular space 1about 3J nm2 articularly numerous in keratini4ed s5uamous epitelium. •
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= = = = = = = = = = = = = = = = = ap ?unction lso called =communicating> )unction. !ap % broad areas "ntecellular space is only 3 nm &ide pposed plasma membranes are perforated by tiny tubes % =conne;ons> Conne;on allo& e;cange of ions and small molecules bet. ad)acent cells = = = = = = = = = = = = = = = = = Hemi#esmosomes (odi0cation on te basal surfaces of epitelial cells. •
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Galf of a desmosomeK Gelps ancor te epitelial cells to te underlying basal lamina 1basement membrane2
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