Recall, from this chapter, that the factor gamma (?) governs both time dilation and length contraction, where ? When you multiply the time in a moving frame by ?, you get the longer (dilated) time in your fixed fame. When you divide the length in a moving frame by ?, you get the shorter (contracted) length in your fixed frame. According to Newtonian mechanics, the momentum of the bus in the problem 1 is ?p? = mv.? According to relativity, it is ?p? = ??mv?. How does the actual momentum of the bus moving at 0.99?c? compare with the momentum it would have if classical mechanics were valid? How does the momentum of an electron traveling at 0.99?c? compare with its classical momentum? Recall, from this chapter, that the factor gamma (?) governs both time dilation and length contraction, where ? When you multiply the time in a moving frame by ?, you get the longer (dilated) time in your fixed fame. When you divide the length in a moving frame by ?, you get the shorter (contracted) length in your fixed frame. A passenger on an interplanetary express bus traveling at ?v? = 0.99?c? takes a 5-minute catnap, according to her watch. Show that her catnap from the vantage point of a fixed planet lasts 35 minutes.

SarahStewart BIOL1040 Exam3notes Chapter42:TheImmuneSystem Lecturegiven3/1/16 • Canfightoffpathogenswithbarriers(skinandmucousmembranes),nonspecific internaldefenses(phagocytosis,naturalkillercells,inflammation),andspecific immuneresponse(cell-mediatedandhumoralimmunity). Innateimmunity–aseriesofdefensesthatactimmediatelyuponinfection • Invertebratesrelysolelyonthis,canconsistof o Exoskeleton o LowpH o Enzymes o Immunecellscapableofphagocytosis • Vertebrateshaveinnateandadaptiveimmunity o Skinandmucousmembranes o Interferons o Neutrophils–phagocyticcells o Naturalkillercells-attackcancercellsandvirus-infectedcells o Macrophages o (Mostofthesearemodifiedwhitebloodcells) o Complementsystem • Tissuedamagetriggerstheinflammatoryresponse,candisinfectinfectedtissues andlimitthespreadofinfection SarahStewart BIOL1040 Exam3notes • Canbelocalizedorwidespread;somebacteriamaymakeittothebloodstreamif notdisinfectedfully,causesbacterialinfection • Bacterialinfectionsbringaboutinflammatoryresponseleadingtosepticshock– highfever,lowbloodpressure Lecturegiven3/10/16 Lymphaticsystem–abranchingnetworkoflymphaticvessels,lymphnodes(filterout bacteria,butcanswellup),andcirculatinglymph(similartointerstitialfluid,buthasless nutrients) • Lymphaticvessels–collectfluidfrombodytissues,returnlymphtoblood • 2mainfunctionsonlymphaticsystem: o Toreturntissuefluidtothecirculatorysystem o Tofightinfection • Aslymphcirculates,itcollectsmicrobes,partsofmicrobes,andmicrobialtoxins; transportsthesetolymphaticorganswheremacrophagesingesttoxinsand lymphocyteshaveanadaptiveresponse Adaptiveimmunity(acquired)–asetofdefensesfoundonlyinvertebratesthatisonly activatedafterexposuretocertainpathogens • Slowerresponse,recognizesspecificpathogens(antigens),andhasa“memory” • Ourcellsarelabeledwithuniquesurfacemembraneproteins(MHCmarkers) thatcharacterizecellsasours,distinguishthesefromforeignparticles o Self–abletorespondtothingsthatareapartofus SarahStewart BIOL1040 Exam3notes o Non-self–whattriggersanimmuneresponse,isnotapartofus Antigens–anyoutsidesubstancethatelicitsanadaptiveimmuneresponse;canbe viruses,bacteria,dust,etc.–anythingforeign • Whileantigenreceptorsareveryspecific,antigensthemselvescanbindto severaldifferentcellsandtheirantigenreceptors Lymphocytes–whitebloodcellsresponsibleforadaptiveimmunity,originatefromstem cellsinthebonemarrow • Differenttypesoflymphocytes o Blymphocytes(Bcells)–continuetodevelopinthebonemarrow; humoralimmuneresponse o Tlymphocytes(Tcells)–developfurtherinthethymusglandtomature; cell-mediatedimmuneresponse o Bothofthesefinishmaturinginlymphaticorgans(lymphnodes,spleen) • BandTcellsdifferentiatefromeachotherandothercellsduringmaturationby formingantigenreceptorsintheirplasmamembrane;allantigenreceptorsona certaincellareidenticalandrespondtoonlyoneantigen • Together,BandTcellswardoffdiseasesandinfectioninbothbodyfluidsand cells–everypersonhascommonanduniqueresponsestocertainantigens Clonalselection–modelforadaptiveimmunitydealingwithantigens • AcertainBcellisselectedandmultipliedinresponsetoanantigen SarahStewart BIOL1040 Exam3notes • SomeoftheseBcellsbecomeeffectorcells,whichsecreteantibodiesintothe bloodandlymph • Othersbecomememorycells,usedifantigenencounteredagain • Primaryvs.secondaryimmunity o Primaryresponseoccursatthefirstencounterwithanantigen,slow o Secondaryresponseoccursatthesecondencounterwithanantigen, faster o Bothactivateeffectorcellsandmemorycells