搜索
SELF-ASSESSMENTINHISTOLOGYQUESTIONS六,CIRCULATORYSYSTEM1Theendocardiumoftheheartconsistsofendothelialcellssuppportedbyathinzoneofdelicatefibroelasticconnectivetissue.(T)2Themajorpartofthemyocardialconductingsystempassesintheepicardium.(F)3Thepeericardialcavityislinedbyendothelium.(F)4TheconductingsystemoftheheartconsistsofhighlymodifiedneuronesknownasPurkinjefibres.(F)5Thecoronaryarteriesandtheirbranchesrepresentthevasavasorumoftheheart.(T)6Inelasticarteries,elastinisdisposedasawelldefinedinternallaminaandamorediffuseexternallamina.(F)7Majordistributingarteeriessuchasthefemoralarteriesaredefinedasmusculararteries.(T)8Unliketherestofthearterialsystem,theaortahasnovasavasorum.(F)9Undernormalcircumstances,thetoneofarteriolarsmoothmuscleistheprincipalfactordeterminingperipheralvascularesistance.(T)10Thearteriolesofhighlyvasculartissuessuchasendocrineglandshaveafenestratedendotheliallining.(F)211Thewalloftheaortacontainsnosmoothmuscle.(F)12Invesselsofthearterialsystem,elastinisdisposedinfenestratedsheetsratherthanasdiscretefibresasinconnectivetissue.(T)13Inthearterialsystemthevasavasorumareconfinedtothetunicaintimaanddonotextendintothetunicamedia.(F)14Atthejunctionofsmallarterieswithlargearteriolestheendothelialliningundergoestransitionfromacuboidaltoanextremelyflattenedform.(F)15Thetunicaadventitiaofarterialvesselsmainlyconsistsofcollagenousconnectivetissue,theperipheryofwhichmergeswithsurroundinglooseconnectivetissues.(T)16Sinusoidsaredefinedaslargediametercapillarieswithmuscularwalls.(F)17Fenestratedcapillarieshaveporesintheendothelialcellsbutnotintheunderlyingcasementmembrane.(T)18Gasescrosscapillarywallsbypassivediffusion.(T)19Post-capillaryvenulesaretheprincipalsiteatwhichleucocytesenterandleavethecirculation.(T)20Autoregulationistheprocesswherebytheconcentrationofveaioustissuemetaabolitesinfluencesbloodflowinthelocalmicrocirculation.(T)21Arteriovenousshuntsarealsoknownasmetarterioles.(F)22Attheoriginofeachcapillarythereisahistologiacllydistinctmuscularsphincterwhichcontrolscapillarybloodflow.(F)23Pericytesareflattenedcellsscatteredbeneaththeendothelialbasementmembranesofcapillariesespeciallyofthecontinuousendotheliumtype.(T)24Theprincipalfunctionoffenestratedcapillariesistofacilitateleucocytepassagetoandfromthecirculation.(F)25Pinocytoticvesiclesareacharacteristicultrastructuralfeatureoftheendothelialcellcytoplasm.(T)26Incontrasttoarteries,thesmoothmuscleofveinwallsisdisposedinalongitudinalmanner.(F)27Venousreturntotheheartfromthelowerlimbsisaidedbyrhythmiccontractionofthemuscularwallsofmediumsizedveins.(F)28Inveins,thetunicaadventitiaisthebroadestlayerofthevesselwall.(T)29Thevalvesofveinsandlymphaticsconsistofdelicateconnectivetissueinvestedbyendothelialcells.(T)30Lymphaticcapillariesmaybedistinguishedhistologicallyfrombloodcapillariesbytheabsenceoferythrocytes,moreabundantleucocytesandthepresenceofprecipitatedplasmaproteins.(T)