AS_Ch 8.4 Blood, tissue fluid and the lymphatic system

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1、THEBLOODREDBLOODCELLSorERYTHROCYTES•containstheglobularproteinhaemoglobin,whichistheredpigmentthatgiveserythrocytestheircolour.•themainfunctionofhaemoglobinistotransportoxygenfromthealveoliinthelungstorespiringcellsinthetissuesofthebody.-theironinhaemoglobinbindsoxygenwhentheconcentrationofoxygeni

2、shigh(asinthelungs).-whentheconcentrationofoxygenislow(asinrespiringbodytissues),theoxygenboundtotheironinhaemoglobinisreleased.•haveshortlifetimes;theircellsurfacemembranesbecomemoreandmorefragilewithtimeandeventuallyerythrocytesruptureandtheremainsarebrokendownbytheliver.Redbloodcellsarecontinuo

3、uslyproducedinthebonemarrow.Thestructureoferythrocytesishighlyadaptedfortheirfunction:1.Shapedlikebiconcavediscs•increasedsurfacearea:volumeratio,whichmeansthatalotofoxygencandiffuseintoandoutofredbloodcellsatanygivenmomentintime.2.Verysmall•everyhaemoglobinmoleculeinaredbloodcellisclosetothecells

4、urfacemembrane,enablingrapidexchangeofoxygenacrossthecellsurfacemembrane.•allowsredbloodcelltotightlysqueezethroughthenarrowcapillaries,bringingoxygenascloseaspossibletotherespiringcells.3.Veryflexible•erythrocytesareabletodeform(changetheirshape),allowingthemtopassthrougheventhetiniestcapillaries

5、.•haveaspecialisedcytoskeletonmadeupofamesh-likenetworkofproteinfibresthatallowsthemtobesquashedintodifferentshapesandthenspringbackintothenormalbiconcaveshape.4.Havenonucleus,nomitochondriaandnoendoplasmicreticulum•lackoforganellesprovidesmorespaceforhaemoglobin,whichmaximisestheamountofoxygentha

6、tcanbecarriedbyeachredbloodcell.WHITEBLOODCELLSorLEUCOCYTES•therearemanydifferentkindsofleucocyteswithawidevarietyofspecificfunctions,althoughallarepartoftheimmunesystemandinvolvedinfightingdisease.•producedinthebonemarrow.•allleucocyteshaveanucleusbuttheshapeofthenucleusvariesindifferenttypesofwh

7、itebloodcells.•mostleucocytesarelargerthanerythrocytes.Onlylymphocytescanbesmaller.•leucocytesareeithersphericalorirregularinshape.•leucocytescanmoveacrossthewallsofcapillariesandintothetissuesofthebody.Twomaingr