hist101: histology
TRANSCRIPT
CourseComponents • Reading:AnthonyMescher,JunqueirasBasicHistologyAtlas,15thediBon
• Ross&Pawlina,Histology,ATextandAtlas,6thediBon,2011
• Lectureseries• SamplequesBonspostedonweb• hOp://docs.neu.edu.tr/staff/deniz.balci/• Virtualmicroscope:histologyguide.org• 1midterm,1finalexam
CourseOutline
• Week1-IntroducBontoHistology• Week2-EpithelialTissues• Week3-ConnecBveTissues• Week4-MuscleTissues• Week5-NervousTissue• Week6-Microscope&BasicHistologicalTechniques
Whatisthedefini>onofHistology?
² HistologyisthescienBficstudyofbiologicalBssues.
“Histo” comes from Greek which means “web” or “tissue”
Whatisthedefini>onofHistology?
² HistologyisthestudyofthemicroscopicstructuresofcellsandBssuesofplantsandanimals.Itiso_encarriedoutbyexaminingathinslice(calleda"secBon")ofBssueunderamicroscope.
WhyarewestudyingHistology?
• Todevelopamentalimageofthemicroscopicappearanceofcells,structures,Bssues,andorgans.
• TocorrelatemicroscopicappearancewithfuncBoninhealthanddisease.
• Toprovideabasisforlaterstudyofanatomyandpathology.
• Becauseit’sawesome.
WheredoesHistologyfitin?
• GrossAnatomy• MicroscopicAnatomy(Histology)
• OtherBiomedicalScienceCourses– Biochemistry– Physiology– Microbiology– Pathology– Pharmacology
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HistologicHierarchyIsthebasicfuncBonalunitofallorganisms.
Cells
CellsthataresimilarorfuncBonsimilarlyaregroupedtogethertoform
Tissues
TissuesaregroupedtogethertoformOrgans
OrgansgroupedtogethertoformtheOrgansystem.
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Ø Bodyhasover200differentcelltypes,100TrillioncellsØ CellscanbeputintofourgroupsaccordingtotheircellfuncBon.
• Neurons
• Musclecells
• Epithelialcells
• ConnecBveBssuecells
Organiza>onoftheBody
MajorTissueTypesØ BasedprimarilyoncellfuncBonØ Correspondtofourmajorcelltypes
Terminology
Tissuesarecomposedof:– Cells– Extracellularmatrix
Organsarecomposedof:– Parenchyma(cellsthatperformmainfuncBonoforgan)
– Stroma(supporBngBssue)
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TheCELL
CellsarethebasicstructuralandfuncBonalunitsofallmulBcellularorganisms.(withthepossibleexcepBonsofvirusesandprions).
Balcı D, 2009
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Prokaryotes–unicellular(e.g.bacteria)Archaea(e.g.thermophiles)Eukaryotes–canbeunicellularormulBcellular(e.g.fungi,animal,human,plants).
Prokaryo>candEukaryo>cCellStructure
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DifferencesInCellularOrganiza>onsofProkaryotesandEukaryotes
Prokaryotes EukaryotesMicroorganism Mostlyunicellular MulBcellularorunicellular
Nucleus No Yes
Membranousorganelles
No Yes(e.g.mitochondria,Golgibodies)
DNAorganisa>on
Circularanddoublestranded
Linear,enclosedinthenucleus
Size 1µm 10–100µm
Cytoskeleton NobutsomeofthemhaveacBnfilaments
Yes(e.g.microtubulesandacBnfilaments)
Metabolism Anaerobicoraerobic aerobic
15 Note:Inprokaryotesribosomesaretheonlycytoplasmicorganelles.TheyaresmallerthaneukaryoBcribosomes.
ORGANELLES
Lightmicroscopeamaximumof2000xmagnificaBon
Walls,vacuoles,cytoplasm,chloroplasts,nucleusandcellmembrane
Electronmicroscopeupto2millionBmes
Ribosomes,endoplasmicreBculum,lysosomes,centrioles,golgibodies
ComponentsofaCell:ThecellisamassofProtoplasmseparatedfromtheexternalenvironmentbyaPlasmaMembrane.TheProtoplasmismadeupoftwocomponents:1. Cytoplasm:thatcontainsØ numerousorganelles:
• Mitochondria• EndoplasmicReBculum• GolgiApparatus• Ribosomes• Lysosomes• Peroxisomes• ThecytoskeletonoftheCell:(a)Microfilaments(b)Intermediatefilaments(c)Microtubules• CentrosomeandcentriolesØ CytoplasmicInclusions
2.Nucleus:thathousesthegenomeofthecell.
In cytoplasmic matrix
Organellesaredescribedasmembranous(membrane-limited)ornon-membranous
• performthemetabolic,syntheBc,energy-requiring,andenergy-generaBngfuncBonsofthecell
• Allcellshavethesamebasicsetofintracellularorganelles,whichcanbeclassifiedintotwogroups:
① membranousorganelles② nonmembranousorganelles-cytoskeleton,centrioles,ribosomes
PlasmaMembrane(Plasmalemma)• Lipidbilayer(2layers).
• 8to10nm• Primarilyconsistsof
phospholipid,cholesterol,andproteinmolecules.
• Cellmembranesareinvolvedinavarietyofcellularprocessessuchasionandnutrienttransport,recogniBonofenvironmentsignal(receptor),adhesion.
• Cellinjuryo_enmanifestsasmorphologicchangesinthecell’splasmamembrane(Blebbing).
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Extracellularspace
Protoplasm
SurfacemoleculesconsBtutealayeratthesurfaceof
thecellcalledcellcoatorglycocalyx.Madeinsidethecellandsecreted
Func>ons• ProtecBon,Metabolism,CellrecogniBon,CellassociaBon• Serveasreceptorsitesforhormones• CellidenBty(organtransplantaBon)
Cytoskeleton
Microfilaments 7nm
Aktin Under plasma membrane cell shape, Support for microvilli in intestinal cell
Microtubules 25 nm
Vimentin Support nuclear envelope , holding skin cells tightly together
Tubulin cause movement of organelles
Intermediate filaments 10 nm
• Maintainscellshape• Facilitatescellmobility• Anchorsthevariousorganelles
• Phagocytosis• Cytokinesis• Cell-cellandcell–ECM
adherence
AssemblyofCytoskeleton
Microfilament Microtubules
- Pointed end Depolymerization
Gelsolin(capping) + Barbed end Polymerization
G-actin,globular
F- actin; filamentous
ATP-dependent
Slowergrowingend
Fastergrowingend
CytoskeletalDrugs
EndoplasmicRe>culum(ER)² BothtypesofERareconBnuouswithone
another.
² playsaroleinthetransportofmaterials
² RoughER-hasribosomes
• Synthesizesandtransportsgeneproducts(exportedproteins)
• qualitycheckpointintheprocessofproteinproducBon.
² SmoothER• synthesizelipidsinthecell.
• storeforCa+2(muscle)
• principalorganelleinvolvedindetoxificaBonandconjugaBonofnoxioussubstances.(liver)
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• Fluorescence micrograph of a cultured mammalian cell stained with ananBbodythatbindstoaproteinretainedintheER.• TheERextendsasanetworkthroughouttheenBrecytosol,sothatallregionsofthecytosolareclosetosomeporBonoftheERmembrane.
TherERismosthighlydevelopedinac>vesecretorycells.Secretorycellsincludeglandularcells,acBvatedfibroblasts,plasmacells,
odontoblasts,ameloblasts,andosteoblasts.
Membrane-boundRibosomesDefinetheRoughER
RibosomesØ Ribosomesarecytoplasmicgranulesthat
helpinthesynthesisofproteins• Someribosomesarefreewithincytoplasm
(polyribosome,polysome)(neurons)-remaininthecell
• mostareboundedtoER-specialisedforsecre>on,lysosomalenzymes
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• IndividualribosomesandpolysomesareNOTvisibleunderlightmicroscope.
• Cellscontaininglargenumbersoffreeribosomesarebasophilic(becauseofthenucleicacidintheribosomes)
GolgiComplex(Body)
• funcBonsinthepost-transla>onalmodifica>on,sor>ngandpackagingofproteins.
• TheGolgiisusuallylocatednearthecellnucleus,andiso_enclosetothecentrosome,orcellcenter.
• TheGolgi complex is composed of 3-15parallelcisternaeandassociatedvesicles
Nucleus
Plasma membrane
Light-microscopeappearance
• Not visible under light microscope but someBmes observed asunstainedimageinsidethewellstainedcytoplasm,calleda"Golgighost"
• Can be demonstrated with heavy metal staining (silver orosmium).
TheGolgiapparatusisespeciallyprominentincellsthatarespecializedforsecre>on,suchasthe
gobletcellsoftheintesBnalepithelium,whichsecretelarge
amountsofpolysaccharide-richmucusintothegut.
Mitochondria(singular:mitochondrion)• Sitesofenergyproduc>on.
• sugars+O2-->ATP+CO2+H2O• mobilepowergenerators
• HasitsownDNA,increasetheirnumbersbydivision,synthesizesomeoftheirstructuralproteins
• decidewhetherthecelllivesordies.(Apoptosis)
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Mitochondriainthelightmicroscope
SomeBmesobservedinfavorablesituaBons(e.g.,liverornervecells)asminiscule,darkdots.
Lysosomes
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• Membrane-boundorganellesthatcontaindiges>veenzymes(proteases,nucleases,glycosidases,lipases,andphospholipases)
• Roundshape-sphericalbodiesboundedbyasinglemembrane&proteinsandmembranearemanufacturedbytheGolgi.
• somecells(osteoclast,neutrophils)mayreleaselysosomalenzymesdirectlyintoECM
Lysosomesinthelightmicroscope
Cells in a kidney tubule shownumerous purple lysosomes (L) inthe cytoplasmic area between thebasally located nuclei (N) andapical ends of the cells at thecenter of the tubule. Usingendocytosis, these cells acBvelytake up small proteins in thelumen of the tubule, degrade theproteins in lysosomes, and thenrelease the resulBng amino acidsforreuse.
Peroxisome
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• singlemembrane-boundedorganellescontainingoxidaBveenzymes.
• funcBontoridthebodyoftoxicsubstanceslikehydrogenperoxide,orothermetabolites.
• TheyareamajorsiteofoxygenuBlizaBonandarenumerousintheliverwheretoxicproductsaregoingtoaccumulate.
CellularDifferen>ta>on
Humanorganismincludes200differentcelltypesallderivedfromzygote
• Cellsarise in thebody fromprogenitororstemcellsandbecomespecializedforoneormoredisBnctfuncBonssuchas• contracBon,nerveconducBon,secreBon,absorpBon,protecBon
• ThisprocessofcellspecializaBonisknownascelldifferen>a>on.• Structural (become very efficient for specialized funcBon) or
morphological (change in shape) modificaBons duringdifferenBaBonareaccompaniedbybiochemicalchanges
• (Ex;formaBonofredbloodcellsrequiresthedifferenBaBngcellstomakespecializedproteinsforoxygentransport).
Vary in their shape and size
Cellstructurecloselyrelatesfunc>on
• MusclecellscontainnumerousorganellesprovidingenergyrequiredformusclecontracBon.
• Nervecellsarelongandthintocarryimpulsesoverdistance.
39 Pictures adapted from www.imgarce.com
TheEndomembraneSystemincludesNucleus,ER,Golgi,PlasmaMembrane,Lysosomes:theseareconnectedbytransportvesicles.
EndocytosisandExocytosis• Thegroupofprocessescalledendocytosisbringsmacromolecules,largeparBcles,smallmolecules,andevenothercellsintotheeukaryoBccell.
• Therearethreetypesofendocytosis:phagocytosis,pinocytosis,andreceptor-mediatedendocytosis.
① PhagocytosisistheengulfingofsolidparBcles.
② Pinocytosisiscellulardrinking.Theengulfingofliquiddroplets.
•
③ Receptor-mediatedendocytosisissimilartopinocytosis,butitishighlyspecificanditoccurswhenthematerialtobetransportedbindstocertainspecificmoleculesinthemembrane.
*Ex;thetransportofinsulinandcholesterolintoanimalcells.
1985- Nobel Prize (Brown & Goldstein)
• Theoppositeofendocytosisisexocytosis.Large molecules that are manufactured in the cell arereleasedthroughthecellmembrane.
Exocytosis
Vesicle-MediatedTransport• VesiclesandvacuolesthatfusewiththecellmembranemaybeuBlizedtoreleaseortransportchemicalsoutofthecellortoallowthemtoenteracell
Inclusions
• Nonlivingpartsofthecell• HavenometabolicacBviBes• Donothavemembrane• Existinthecytoplasm
Glycogenlipiddropletspigmentgranulescristaloids(ReinkecrystalsinLeydigcells)Secre>ongranulesResidualbody(waste)lipofuscin