系统解剖学英文教学课件：Veins Lymphatic System

Veins

LymphaticSystemVeins2Veins3Veins-NeckTheveinsoftheneckdifferfromthearteries,theycanbedescribedasfollows:BranchCourseTributariesInternaljugularveinDescendswithinthecarotidsheath,anduniteswiththesubclavianveinposteriortotheclavicletoformthebrachiocephalicvein.Acontinuationofthesigmoidsinusasitexitstheskullviathejugularforamen.Inferiorpetrosalsinus.Facial.Lingual.Superiorandmiddlethyroid. ExternaljugularveinItarisesneartheangleofthemandible,anddescendsverticallyacrosssternocleidomastoidtodrainintothesubclavianvein.Retromandibular.Posteriorauricular.Internaljugular.Posteriorexternaljugular.Transversecervical.Suprascapular. 4InternalJugularVeinTributaries

Itisacontinuationofthesigmoidsinusasitexitstheskullviathejugularforamen.Italsoreceivesbloodfrom:Inferiorpetrosalsinus.Facialvein.Lingualvein.Pharyngealvein.Superiorandmiddlethyroidveins.Course

Theinternaljugularveindescendswithinthecarotidsheath,andcomestolielateraltotheinternalandcommoncarotidarteries.Atthesuperiorandinferiorends,theinternaljugularveinformsdilatedbulbs.Draininto

Ituniteswiththesubclavianveinposteriortotheclavicletoformthebrachiocephalicvein.Regionsdrained

Brain,Cranialcavity,Face,Neck.5AneedleandcathetermaybeinsertedintotheIJVfordiagnosticortherapeuticpurposes.Therightinternaljugularispreferablebecauseitisusuallylargerandstraighter(Geretal.,1996).Duringthisprocedure,theclinicianpalpatesthecommoncarotidarteryandinsertstheneedleintotheIJVjustlateraltoitata30ºangle,aimingattheapexofthetrianglebetweenthesternalandtheclavicularheadsoftheSCM,thelessersupraclavicularfossa.Theneedleisthendirectedinferolaterallytowardtheipsilateralnipple.InternalJugularVeinPunctureExternalJugularVeinTributaries

Formedbytheunionoftheretromandibularandposteriorauricularveins.Italsoreceivesbloodfrom:Internaljugularvein.Posteriorexternaljugularvein.Transversecervicalvein.Suprascapularvein.Anteriorjugularvein.Course

Itarisesneartheangleofthemandible,inferiortotheparotidglandanddescendsverticallyacrosssternocleidomastoid.


Drainsinto


Subclavianvein.

Regionsdrained

Shoulder.
Headandneck.7DuralFoldsandSinusesInthreeplacesthemeningeallayeroftheduramaterfoldsinwardstoformdoublethicknesssheetsknownasduralfolds;theyhelptoholdthebraininplace.Atcertainlocationstheperiostealandmeningeallayersoftheduramaterarepulledawayfromeachothertocreateaspace,aduralsinus.Thesesinusesarefilledwithvenousbloodfromthebrainviathecerebralveins.Theydrainbloodintotheinternaljugularvein.8DuralFoldsandSinuses9DuralFoldsandSinuses10DuralSinusesSuperiorSagittalSinusInferiorSagittalSinusCavernousSinusInferiorPetrosalSinusSuperiorPetrosalSinusTransverseSinusSigmoidSinusOccipitalSinus11SuperiorSagittalSinusTributariesItreceivesthesuperiorcerebralveins.CourseItoriginatesnearthecristagallioftheethmoidboneandrunsalongthemediansagittalplaneoftheskullintheattachedmarginofthefalxcerebri.DrainsintoRighttransversesinus.RegionsdrainedBrain.12InferiorSagittalSinusTributariesTheinferiorsagittalsinuscombineswiththegreatcerebralveintoformthestraightsinus.CourseItliesintheposterior2/3rdsoftheinferiorfreemarginofthefalxcerebri.13CavernousSinusTributariesSuperiorophthalmicvein.Cerebralveins.Sphenoparietalsinus.CourseThecavernoussinusislocatedonthebodyofthesphenoidbonebetweenthecranialandmeningeallayersoftheduramater.Theoculomotor,trochlearandabducentnervesandtheinternalcarotidarteryliewithinitswalls.DrainsintoSuperiorpetrosalsinus.Inferiorpetrosalsinus.14InferiorPetrosalSinusTributariesItarisesfromthecavernoussinus.CourseTheinferiorpetrosalsinusliesatthelowerborderofthepetrousbone,occupyingagrooveintheregionofthepetro-occipitalsuture.DrainsintoSuperiorbulboftheinternaljugularvein.RegionsdrainedInternalear.Brainstem.Cerebellum.15SuperiorPetrosalSinusTributariesItoriginatesfromthecavernoussinus.CourseItissituatedintheanteriorpartoftheattachedmarginofthetentoriumcerebelliandoccupiesagrooveontheupperborderofthepetrouspartofthetemporalbone.DrainsintoSigmoidsinus.RegionsdrainedBrain.16TransverseSinusTributariesRight:isacontinuationofthesuperiorsagittalsinus.Left:isacontinuationofthestraightsinus.CourseThetransversesinuspasseslaterallyacrosstheoccipitalboneintheattachedmarginofthetentoriumcerebelli.DrainsintoSigmoidsinus.RegionsdrainedBrain.17SigmoidSinusTributariesThesigmoidsinusdescendsfromthetransversesinus.CourseIthasanS-shapedcourse,groovingthetemporalandoccipitalbonesandisthemainsiteofdrainagefortheduralvenoussinussystem.DrainsintoItcontinuesastheinternaljugularveinasitpassesthroughthejugularforamen.RegionsdrainedBrain.Meninges.18OccipitalSinusTributariesTheoccipitalsinuscommunicateswiththe:Internalvertebralvenousplexus.Sigmoidsinus.Basilarvenousplexus.CourseTwosmallbranchespassaroundthemarginsoftheforamenmagnumanduniteinthemid-linewheretheyarelinkedtotheconfluenceofsinusesbyasinglesinusthatascendsintheattachedmarginofthefalxcerebelli.19ThefollowingVeinsaredifferentTheveinsoftheheadaredifferentfromthearteriesduepartlytothedifferencesoftheveinsintheneck.Thevenousdrainageofthebrainismarkedlydifferentfromthethearterialsupply:TransversefacialveinRetromandibularvein20TransverseFacialVeinTributaries

Facialvein.Course

Thetransversefacialveintraversesthezygomaticarchtoserveasaconnectingbranchbetweenthefacialandsuperficialtemporalveins.Drainsinto

Superficialtemporalvein.Regionsdrained

Zygomaticregion.21RetromandibularVeinTributariesFormeddeeptotheparotidglandbytheunionofthesuperficialtemporalandthemaxillaryveins.CourseIttravelsthroughtheparotidgland,dividingintoanteriorandposteriordivisions.DrainsintoAnteriordivision:facialvein.Posteriordivision:posteriorauricularvein,formingtheexternaljugularvein.RegionsdrainedSideoftheheadandscalp.Deepstructuresoftheface.2223Veins-ThoraxThesuperiorvenacavadescendstodrainintotherightventricleoftheheart,theinferiorvenacavaascendstoit.Venousdrainageofthethoraxisthereforequitedifferenttothatofthearteries.Theazygossytemofveinsinparticular.24Veins-Thorax25Veins-ThoraxThefollowingveinsdonothaveequivalentarteries,oraremarkedlydifferentfromtheartery.AccessoryhemiazygosveinAscendinglumbarveinAzygosveinBrachiocephalicveinHemiazygosveinPulmonaryveins26AccessoryHemiazygousVeinTributaries

Posteriorintercostalveins4to8.Leftbronchialveins.Course

ItdescendsontheleftofthevertebralcolumntothebodyofT7whereitunitswiththeazygosvein.Drainsinto

Azygosvein.Regionsdrained

Leftchestwall.27AscendingLumbarVeinTributariesAbranchofthecommoniliacvein.Italsoreceivesbloodfromthefollowingveins:Iliolumbarveins.Lumbarveins.Course

ItascendsbetweenpsoasmajorandthelumbartransverseprocessestopassbehindthecrusofthediaphragmatL1.Drainsinto

Right:uniteswiththesubcostalveintoformtheazygosvein.Left:uniteswiththesubcostalveintoformthehemiazygosvein.Regionsdrained

Posteriorabdominalwall.28AzygousVeinTributaries

Formedbytheunionoftherightascendinglumbarveinandtherightsubcostalvein.Italsoreceivesbloodfromthefollowingveins:Rightposteriorintercostalveins2to8.Hemiazygosvein.Accessoryhemiazygosvein.Esophagealveins.Rightbronchialvein.Course

ItascendsintheabdomenanteriortotheupperlumbarvertebraeandintheposteriormediastinumanteriortothebodiesofT12toT4.Drainsinto

Superiorvenacava.Regionsdrained

Lateralandposteriorwallsofthetrunk.Esophagus.Bronchialtree.29BrachiocephalicVeinTributaries

Formedbytheunionoftheinternaljugularandsubclavianveins.Italsoreceivesbloodfromthefollowingveins:Vertebralvein.Internalthoracicvein.1stposteriorintercostalvein.Course

Right:about3cmlong,itdescendsmediallybehindtheclavicle.Left:about6cmlong,itdescendsobliquelyright,behindthemanubrium.Drainsinto

Ituniteswithitsoppositetoformthesuperiorvenacava.Regionsdrained

Headandneck.Upperlimb.Anteriorchestwall.30HemiazygousVeinTributaries

Formedbytheunionoftheleftascendinglumbarveinandthesubcostalveins.Italsoreceivesbloodfromthefollowingveins:Leftposteriorintercostalveins9to11.Course

ItascendsanteriortothebodiesofT12toT8posteriortotheaortatopassbehindtheleftcrusofthediaphragm.Drainsinto

Azygosvein.Regionsdrained

Leftchestwall.31PulmonaryVeinsCourse

Numerousbranchescoursethroughtherightlungbeforeunitingtoformtwopulmonaryveinsthatleavethelungatthehilum.Pulmonaryveinsaretheonlyveinstocontainarterialblood.Drainsinto

Heart:leftatrium.Regionsdrained

Lungs.323334Veins-ABDOMENVeins-ABDOMENTheInferiorvenacavaliestotherightofandposteriortotheabdominalaorta.formedatthelevelofL4bytheunificationofthecommoniliacveins.Venousdrainageoftheabdomenisquitedifferenttothatofthearteriesduetothearrangementofthehepaticportalsystemwhichdirectsvenousbloodfrommostoftheabdominalorganstotheliver,ratherthandirectlytotheheart.Apartfromtheportalsystem,thefollowingdifferencescanalsobeseen:AscendinglumbarveinAzygosveinRenalveinsOvarian/testicularvein36Veins-ABDOMEN37AscendingLumbarVeinTributariesAbranchofthecommoniliacvein.Italsoreceivesbloodfromthefollowingveins:Iliolumbarveins.Lumbarveins.Course

ItascendsbetweenpsoasmajorandthelumbartransverseprocessestopassbehindthecrusofthediaphragmatL1.Drainsinto

Right:uniteswiththesubcostalveintoformtheazygosvein.Left:uniteswiththesubcostalveintoformthehemiazygosvein.Regionsdrained

Posteriorabdominalwall.38AzygousVeinTributaries

Formedbytheunionoftherightascendinglumbarveinandtherightsubcostalvein.Italsoreceivesbloodfromthefollowingveins:Rightposteriorintercostalveins2to8.Hemiazygosvein.Accessoryhemiazygosvein.Esophagealveins.Rightbronchialvein.Course

ItascendsintheabdomenanteriortotheupperlumbarvertebraeandintheposteriormediastinumanteriortothebodiesofT12toT4.Drainsinto

Superiorvenacava.Regionsdrained

Lateralandposteriorwallsofthetrunk.Esophagus.Bronchialtree.39RenalVeinsTributariesFormedatthehilusofthekidneybytheunionoftheinterlobarveins.Theyalsoreceivebloodfromthefollowingveins:Suprarenalveins.Inferiorphrenicveins.Leftovarian/testicularvein.Course

Left:itpasseshorizontallytotherightinfrontoftheleftrenalarteryandaorta,behindthepancreas.Right:itpasseshorizontallytotheleftbehindthedescendingduodenum.Drainsinto

Inferiorvenacava.Regionsdrained

Kidneys.Suprarenalglands.40RenalVeins4142Ovarian/TesticularVeinsCourseTwoveins,onelyingoneithersideoftheovarianartery,ascendinthebroadligamentandthenonpsoasmajor,behindtheperitoneum.MalehomologyTheyarehomologouswiththetesticularveinsinthemale.DrainsintoRight:inferiorvenacava.Left:leftrenalvein.RegionsdrainedOvaries.Ureters.Uterus.4344ShortBreakHepaticPortalSystem45HepaticPortalSystemThehepaticportalsystemfunctionstofilterthedeoxygenatedbutnutrientrichbloodreceivedfromthedigestivesystemoftoxinsandbacteriabeforeitisreturnedtothehearttobedistributedtotherestofthebody.Theliverreceivesvenousbloodfromtheesophagus,stomach,smallandlargeintestines,gallbladder,pancreasandspleenviathelargeportalvein.Onreachingthelivertheportalveindividesintotwolargebranches(leftandright),whichentertheliverandcontinuallybranchtoformhepaticsinusoidswithinallfourlobesoftheliver.Superiorlythehepaticsinusoidsunitetoformthehepaticveinswhichexittheliverfromitsposteriorsidetoentertheinferiorvenacava.Fromtheinferiorvenacavathebloodistransportedtotherightatriumwhereitentersintothepulmonarycirculation. 46HepaticPortalSystem47HepaticPortalSystemGastric,splenic,superior&inferiormesentericandgastroepiploicveinsDeoxygenated,nutrientrichbloodisreceivedfromtheoesophagus,stomach,smallintestine,largeintestine,gallbladder,pancreasandspleen.PortalveinsThegastric,splenic,mesentericandgastroepiploicveinsalldrainintotheportalveinwhichascendstotheliver.Left&rightportalveins

Onreachingthelivertheportalveindividesintoleftandrightportalveinswhichentertheliver.Hepaticsinusoids

Theportalveinscontinuallybranchtoformhepaticsinusoidswithinthefourlobesoftheliver.HepaticveinsThehepaticsinusoidsunitetoformthehepaticveins,whichexittheliverposteriorlytoentertheinferiorvenacava.Inferiorvenacava

Theinferiorvenacavatransportsthebloodtotherightatrium.RightatriumTherightatriumsqueezesthebloodintotherightventriclewhereitispumpedintothepulmonarycirculation.48HepaticPortalSystem49Venousdrainageofthespleen,pancreas,gallbladder,andtheabdominalpartofthegastrointestinaltract,exceptfortheinferiorpartoftherectum,isthroughtheportalsystemofveins,whichdeliverbloodfromthesestructurestotheliver.PortalVeinTheportalveinisthefinalcommonpathwayforthetransportofvenousbloodfromthespleen,pancreas,gallbladder,andtheabdominalpartofthegastrointestinaltract.Itisformedbytheunionofthesplenicveinandthesuperiormesentericvein

posteriortotheneckofthepancreasatthelevelofvertebraLII.50Ascendingtowardstheliver,theportalveinpassesposteriortothesuperiorpartoftheduodenumandenterstherightmarginofthelesseromentum.Asitpassesthroughthispartofthelesseromentum,itisanteriortotheomentalforamenandposteriortoboththebileduct,whichisslightlytoitsright,andthehepaticarteryproper,whichisslightlytoitsleft.PortalVein51Onapproachingtheliver,theportalveindividesintorightandleftbranches,whichentertheliverparenchyma.

PortalVein52Tributariestotheportalveininclude:rightandleftgastricveinsdrainingthelessercurvatureofthestomachandabdominalesophagus;cysticveinsfromthegallbladder;thepara-umbilicalveins,whichareassociatedwiththeobliteratedumbilicalveinandconnecttoveinsontheanteriorabdominalwall.PortalVein53Anastomosesprovideacollateralcirculationincasesofobstructionintheliverorportalvein.Here,theportaltributariesaredarkerblueandsystemictributariesarelighterblue.

Aindicatesitesofanastomoses.Aisbetweenthesubmucosalesophagealveinsdrainingintoeithertheazygosvein(systemic)ortheleftgastricvein(portal);whendilatedtheseareesophagealvarices.PortosystemicAnastomosis54Bisbetweentheinferiorandmiddlerectalveinsdrainingintotheinferiorvenacava(systemic)andthesuperiorrectalvein,continuingastheinferiormesentericvein(portal).Thesubmucosalveinsinvolvedarenormallydilated(varicoseinappearance),eveninnewborns.Whenthemucosacontainingthemprolapses,theyformhemorrhoids.(Thevaricoseappearanceoftheveinsandtheoccurrenceofhemorrhoidsarenottypicallyrelatedtoportalhypertension,asiscommonlystated)PortosystemicAnastomosis55Cshowsparaumbilicalveins(portal)anastomosingwithsmallepigastricveinsoftheanteriorabdominalwall(systemic);thismayproducethecaputmedusae.D

isontheposterioraspects(bareareas)ofsecondarilyretroperitonealviscera,ortheliver,wheretwigsofvisceralveinsorexample,thecolicvein,splenicveins,ortheportalveinitself(portalsystem)anastomosewithretroperitonealveinsoftheposteriorabdominalwallordiaphragm(systemicsystem).PortosystemicAnastomosis56Whenthepressureintheportalveiniselevated,venousenlargement(varices)tendtooccuratandaroundthesitesofportosystemicanastomosesandtheseenlargedveinsarecalled: Hemorrhoids

attheanorectaljunction; Esophagealvaricesatthegastroesophagealjunction; Caputmedusaeattheumbilicus.Esophagealvaricesaresusceptibletotraumaand,oncedamaged,maybleedprofusely,requiringurgentsurgicalintervention.57Whenthepressureintheportalveiniselevated,venousenlargement(varices)tendtooccuratandaroundthesitesofportosystemicanastomosesandtheseenlargedveinsarecalled: Hemorrhoidsattheanorectaljunction; Esophagealvaricesatthegastroesophagealjunction; Caputmedusaeattheumbilicus.Esophagealvaricesaresusceptibletotraumaand,oncedamaged,maybleedprofusely,requiringurgentsurgicalintervention.5859606162Veins-PELVISVeins-PELVISTheinferiorvenacavaliestotherightofandposteriortotheabdominalaorta.itisformedatthelevelofL4bytheunificationofthecommoniliacveinswhichlieposteriortothecommoniliacarteries.Venousdrainageofthepelvisgenerallymirrorsthatofthearteries.Theveinstendtoformthickerplexusesaroundthepelvicorgans.64Veins-PELVISVeins-PELVIS67Veins-UpperLimbVeins-UpperLimbVeins-ShoulderandArm70Veins-ShoulderandArmVeins-ShoulderandArmThedeepveinsofthearmfollowthepathsofthearteriesandarenamedaccordingly.Therearehoweversomeadditionalvesselswhichliejustundertheskinandformasuperficialvenousnetwork.Theyarenamedasfollows:BasilicCephalicMediancubitalvein72BasilicVeinTributaries

Mediancubitalvein.Dorsalvenousplexus.Superficialveinsoftheforearm.Course

Itappearsmediallyonthedorsumofthehandandascendsthemedialaspectoftheforearmtocontinueintothearmwhereitpiercesthedeepfasciamedialtobiceps.Drainsinto

Ituniteswiththebrachialveinstoformtheaxillaryveinatthelowerborderofteresmajor.Regionsdrained

Superficialaspectofthemedialsideofthehandandforearm.73CephalicVein74Tributaries

Dorsalvenousplexus.Mediancubitalvein.Superficialveinsoftheforearm.Course

Itpassessuperficiallyupthelateralborderoftheforearm,crossestheelbowandascendsthearmlateraltobicepsandmedialtothedeltoidwhereitpiercestheclavipectoralfascia.Drainsinto

Axillaryvein.

RegionsdraineSuperficialpartsofthelateralhandandforearm.MedianCubital

Vein75Tributaries

Cephalicvein.Course

Themediancubitalveinascendsmediallyinthecubitalfossa,superficialtothebicipitalaponeurosis.Drainsinto

Basilicvein.Regionsdrained

Superficialforearmandhand.Veins-Forearm(sameasarm)Thedeepveinsoftheforearmfollowthepathsofthearteriesandarenamedaccordingly.Therearehoweversomeadditionalvesselswhichliejustundertheskinandformasuperficialvenousnetwork.Theyarenamedasfollows:BasilicCephalicMediancubitalvein76Veins-Forearm(sameasarm)Veins-HandThedeepveinsofthehandfollowthepathsofthearteriesandarenamedaccordingly.Therearehoweversomeadditionalvesselswhichliejustundertheskinandformasuperficialvenousnetwork.Theyarenamedasfollows:DorsalVenousArch78DorsalVenousArchTributaries

Dorsalmetacarpalveins.Dorsaldigitalveinsofthethumb.Course

Thisplexusofveinsliesoverthemetacarpalssuperficialtotheextensortendons.Drainsinto

Laterally:cephalicvein.Medially:basilicvein.Regionsdrained

Superficialstructuresofthedorsumofthehand.79Veins-Hand81Veins-LowerLimbVeins-LowerLimbSuperficialVeinsoftheLowerLimbThetwomajorsuperficialveinsinthelowerlimbarethegreatandsmallsaphenousveins.Mostoftheirtributariesareunnamed.Veins-HipandThighThedeepveinsofthethighfollowthepathsofthearteriesandarenamedaccordingly.Therearehoweversomeadditionalvesselswhichliejustundertheskinandformasuperficialvenousnetwork.Theyarenamedasfollows:Long(Great)saphenousvein85Long(Great)SaphenousVeinTributaries

Dorsalvenousarch.Course

Thelongestveininthebody,thelongsaphenousveinpassesanteriortothemedialmalleolusthenascendsthemedialsideofthelegandthightothefemoraltriangle.Drainsinto

Femoralvein.Regionsdrained

Skinofthelowerlimb.86Long(Great)SaphenousVein87Thegreatsaphenousveinhas10-22valves,whicharemorenumerousinthelegthaninthethigh.Thesevalvesareusuallylocatedjustinferiortotheperforatingveins.Theperforatingveinsalsohavevalves.Venousvalvesarecusps(flaps)ofendotheliumwithcup-likevalvularsinusesthatfillfromabove.Whentheyarefull,thevalvecuspsoccludethelumenofthevein,therebypreventingrefluxofblooddistally,makingflowunidirectional.Long(Great)SaphenousVeinVeins-LegThedeepveinsofthelegandfootfollowthepathsofthearteriesandarenamedaccordingly.Therearehoweversomeadditionalvesselswhichliejustundertheskinandformasuperficialvenousnetwork.Theyarenamedasfollows:LongsaphenousveinShortsaphenousvein.89ShortSaphenousVeinTributaries

Theshortsaphenousveinisthelateralcontinuationofthedorsalvenousarch.Course

Itpassesposteriortothelateralmalleolusandascendsthecalfbetweenthetwoheadsofgastrocnemius.Drainsinto

Poplitealvein.Regionsdrained

Skinofthelateralsideofthefootandleg.90Frequently,thegreatsaphenousveinanditstributariesbecomevaricose(dilatedsothatthecuspsoftheirvalvesdonotclose).Varicoseveinsarecommonintheposteromedialpartsofthelowerlimbandmaycauseconsiderablediscomfort.Varicoseveinsformwhenthevalvesthatusuallypreventbloodflowfromthedeepveinsthroughtheperforatingveinstothesuperficialveinsareincompetent.Whenthevalveswithinthegreatsaphenousveinitselfareincompetent,thepullofgravityontheuninterruptedcolumnofbloodresultsinahigherintraluminalpressure,whichalsoexacerbatesvaricosities.Asaresult,thesuperficialveinsbecometortuousanddilated.VaricoseVeinsVeins-FootThedeepveinsofthefootfollowthepathsofthearteriesandarenamedaccordingly.Therearehoweversomeadditionalveinswhichliejustundertheskinandformasuperficialvenousnetwork.Theyarenamedasfollows:DorsalvenousarchDorsalmetatarsalveinsLongsaphenousveinShortsaphenousvein.92DorsalVenousArchTributaries

Dorsalmetatarsalveins.Superficialveins.Course

Itliestransverselyacrossthedorsumofthefoot,superficialtotheextensortendons.
DrainsintoLongandshortsaphenousveins.

RegionsdrainedDorsalaspectofthetoes.93DorsalMetatarsalVeins94Tributaries

Theyarecontinuationsofthedorsaldigitalveins.Course

Theypassproximallyonthedorsalinterosseousmusclesintheintermetatarsalspaces.Drainsinto

Dorsalmetatarsalvein1:dorsalispedisvein.Dorsalmetatarsalvein2to4:arcuatevein.Regionsdrained

Dorsalsurfaceofthetoes.95ShortBreakLymphaticSystemTheLymphaticSystemHeart

ArteryCapillariesVeinCellTissuefluidLymphaticcapillaryLymphaticvesselLymphatic

nodeLymphatictrunkLymphaticductLymphaticSystemThelymphaticsystemconsistsofanetworkofvessels,nodesandorgans,locatedthroughoutthetissuesofthebody.Functions:

MaintainingfluidbalancebydrainingexcessfluidfromthetissuesDefendingthebody

againstdiseasebyproducingandtransportinglymphocytesandDigestingfats

fromtheintestineandtransportthemintotheblood.9899LymphaticSystemLymphaticVesselsLymphvesselsoriginateastinyhair-likecapillariesintheinterstitialspacesbetweencells.Thesecapillariesjointogethertoformlargerlymphaticvesselsthataresimilarinstructuretoveins.

Thesevesselsaccompanyveinsandarteriesandareoftenlocatedsuperficially.

Unlikethecirculatorysystem,thelymphaticfluidwithinthesevesselsisnotpumpedaroundthebodyandinsteadreliesoncompressionfromthesurroundingmusclesandvessels,breathing,gravityanddifferingpressuregradientstopushitthroughthesystem. 101LymphaticvesselWallsThickness:Thin(thinnerthanveins).Composition:Simpleoverlappingsquamouscellsthatformaone-wayvalve;itallowsfluidtoenterthevesselandpreventslymphfromleaving.Permeability:Morepermeablethanthewallsofbloodcapillaries.ValvesFrequency:Morefrequentthanthosefoundinveins.Function:Likeveins,thevalvespreventthelymphflowingbackwardsalongthevessel. 103LymphaticVessels-FeaturesFluidbalance Fluidsimilartobloodplasma,calledinterstitialfluid,

leachesfromthebody'sminutebloodcapillariesintothesurroundingtissue.Itbatheseachcellandsupplieseachonewithnutrients,oxygenandwater,whilstremovingurea,carbondioxideandwater.30litersofinterstitialfluidwillleavethearterialcapillarieseveryday,butonly27litersoffluidwillreturntothevenouscapillaries.

Lymphaticvesselsfunctiontodrainthisexcessfluidfromthetissuesaslymphandreturnitintothebloodcirculation.

Digestionoffats

Somefatsaretoolargetopassthroughthecapillarywallsofthesmallintestinetoenterthebloodcirculation,andarethereforeunabletobeabsorbedbythebody.Lymphaticvesselsknownaslactealsdoallowtheselargefatstopassintothem,wheretheyarethentransported