医学英语教程Chapter 2.docx

医学英语教程Chapter 2.docx

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医学英语教程Chapter2

Chapter2Termspertainingtothebodyasawhole

I.StructuralOrganizationofthebody.

Cells

Thecellsisthefundamentalunitofalllivingthings（animalorplant）.Cellsareeverywhereinthehumanbody-everytissue,everytissue,everyorganismadeupoftheseindividualunits.

SimilarityinCells.Allcellsaresimilarinthattheycontainagelatinouissubstancecomposedofwater,protein,sugar,acids,fats,andvariousminerals.Severalpartsofacellwithanelectronmicroscope.LabelthestructuresonFigure2-1.Throughoutthebook,numbersinbracketsindicatethattheboldfacedtermprecedingitistobeusedinlabeling.

Thecellmembranenotonlysurroundsandprotectsthecell,butalsoregulateswhatpassesintoandoutofthecell.

Thenucleuscontrolstheoperationsofthecell.Itdirectsce;;dovosopmamddeterminesthestructureandfunctionofthecell.

Chromosomesarerod-likestructureswithinthenecleus.Allhumanbodycellscontain23pairsofchromosomes.Eachspermandeggcellhasonly23unpairedchromosomes.Aftertheeggandspermcellsunitetoformtheembryo,eachcelloftheembryo,eachcelloftheembryothenhas46chromosomes

Chromosomescontainregionscalledgenes.Thesearesevveralthousandgenes,inanorderlysequence,oneverychromosome.EachgeneiscomposedofachemicalcalledDNA.DNAregulatestheactivitiesofthecellbyitssequenceoneachchromosome.TheDNAsequenceresemblesaseriesofrecipesincode.Thecode,whenpassedoutofthenucleustotherestofthecell,directstheactivitiesofthecell,suchascelldivisionandsynthesisofproteins.

Chromosomeswithinthenecleusareanalyzedintermsoftheirsize,arrangement,andnumberbyperformingakarytype.Karyotypingofchromosomesdetermineswhetherthechromosomesarenormalinnumberandstructure.Forexample,obstetriciansoftenrecommendanamniocentesisforapregnantwomansothatthekaryotypeofthebabycanbeexamined.Figure2-3showsakaryotype,orchromosomemap,ofanormalmale.Thechromosomeshavebeentreatedwithchemicalssothatbandscanbeseen.

Ifababyisbornwithanabnormalnumberifchromosomes,seriousproblemscanresult.InDownsyndrome,thekaryotypeshows47chromosomesinsteadofthenormalnumberof46.Theextranumber21chromosomeresultsinthedevelopmentofachildwithDownsyndrome.Itsincidenceisabout1inevery750livebirths,butasthemother’sageincreases,thepresenceofthechromosomalabnormalityincreases.AtypicalDownsyndromeinfantisbornwithphysicalmalformationsthatmayincludeasmall,flattenedskull;ashort,flat-bridgednose;wide-set,slantedeyes;andshort,broadhandsandfeetwithawidegapbetweenthefirstandsecondtoes.Reproductiveorgansareoftenunderdeveloped,congenitalheartdefectsarenotuncommon,andsomedegreeofmentalretardationisevident.

ContinuelabelingFigure2-1

Cytoplasmincludesallthematerialoutsidethenucleusandenclosedbythemembrane.Itcarriesontheworkofthecell.Thecytoplasmcontains:

Mitochondriaaresmall,sausage-shapedbodiesthat,likeminiaturepowerplants,produceenergybyburningfoodinthepresenceofoxygen.Duringthischemicalprocess,calledcatabolism,complexfoodsarebrokendownintosimplersubstances.Thecatabolismofsugarandfatreleasesneededenergytodotheworkofthecell.

Endoplasmicreticulumisanetworkofcanalswithinthecell.Thesecanalsareacellulartunnelsysteminwhichproteinsaremanufacturedforuseinthecell.Thisprocessofbuildingupcomplexmaterials,suchasproteins,fromsimplerpartsiscalledanabolism.Durininganabolism,smallpievesofproteinarefittedtogetherlikelinksinachaintomakelargerproteins.

Thetwoprocesses,anabolismandcatabolism,areknownasmetabolism.Metabolismisthetotalofthechemicalprocessesoccurringinacell.Ifapersonhasa“fastmetabolism,”thenfoods,suchassugarandfat,arethoughttobeusedupveryquickly,andenergyisreleased.Ifapersonhasa“slowmetabolism,”foodsarethoughttobeburnedslowly,andfataccumulatesincells.

StudySection1

Practicespellingeach,term,andknowitsmeaning.

anabolismProcessofbuildingupcomplexmaterialfromsimplematerials.

catabolismProcessofbreakingdowncomplexmaterialstoformsimplersubstancesandreleaseenergy

cellmembraneStructuresurroundingandprotectingthecell.Itdetermineswhatentersandleavesthecell

chromosomesRod-shapedstructuresinthenucleusthatcontainregionsofDNAcalledgenes.Theseare46chromosomesineverycellexceptfortheeggandspermcells,whichcontainonly23individual,unpairedchromosomes.

CytoplasmAllthematerialthatisoutsidethenucleusandyetcontainedwithinthecellmembrane

DNAChemicalfoundwithineachchromosome.Arrangedlikeasequenceofrecipesincode,itdirectstheactivitiesofthecell.

Endoplasmicreticulumstructurewithinthecytoplasm.Siteinwhichlargeproteinsaremadefromsmallerproteinpieces.Ribosomesarefoundontheendoplasmicreticulum

genesregionsofDNAwithineachchromosome

karyotypePictureofchromosomesinthenucleusofacell.Thechromosomesarearrangedinnumbericalordertodeterminetheirnumberandstructure

metabolismThetotalofthechemicalprocessesinacell.Ittincludesbothcatabolismandanabolism

mitochondriaStructuresinthecytoplasminwhichfoodsareburnedtoreleaseenergy

nucleusControlcenterofthecell.Itcontainschromosomesanddirectstheactivitiesofthecell

DifferencesinCells.Cellsaredifferent,orspecialized,throughoutthebodytocarryouttheirindividualfunctions.Forexample,amuscleislongandslenderandcontainsfibersthataidincontractingandrelaxing;anepithelialcellmaybesquareandflattoprovideprotection;anervecellmaybelongandhavevariousfibrousextensionsthataidinitsjobofcarryingimpulses;afatcellcontainslarge,emptyspacesforfatstorage.Theseareonlyafewofthemanytypesofcellsinthebody.Figure2-5illustratesthedifferentsizesandshapesofmuscle,nerve,fat,andepithelialcells.

Tissues

Atissueisagroupofsimilarcellsworkingtogethertodoaspecificjob.Ahistologistisascientistwhospecializesinthestudyoftissues.Differenttypesoftissuesinclude.

EpithelialTissue,locatedalloverthebody,formstheliningsofinternalorgans,andtheoutersurfaceoftheskincoveringthebody.Italsolinesexocrineandendocrineglands.Thetermepithelialoriginallyreferredtothetissueabovethebreastnipple.Nowitdescribesalltissuethatcoverstheoutsideofthebodyandlinestheinnersurfaceofinternalorgans.

MuscleTissue.Voluntarymusclefoundinarmsandlegsandpartsofthebodywheremovementisunderconsciouscontrol.Involuntarymuscle,foundintheheartanddigestivesystem,aswellasotherorgans,allowsmovementthatisnotunderconsciouscontrol.Cardiacmuscleisaspecializedtypeofmusclefoundonlyintheheartandcanbeseenbeatingina6-week-oldfetus.

ConnectiveTissue.Examplesarefat,cartilage,andblood.

NerveTissue.Nervertissueconductsimpulsesallovethebody.

Organs

Organsarestructurescomposedofseveralkindsoftissue.Forexample,anorgansuchasthestomachiscomposedofmuscletissue,nervetissue,andglandularepithelialtissue.Themedicaltermforinternalorgansisviscera.Examplesofabdominalvisceraaretheliver,stomach,intestines,pancreas,spleen,andgallbladder.

Systems

Systemsaregroupsoforgansworkingtogethertoperformcomplexfunctions.Forexample,themouth,esophagus,stomach,andsmallandlargeintestinesareorgansthatdotheworkofthedigestivesystemtodigestfoodandabsorbitintothebloodstream.

Examinethebodysystemslistedbelowwiththeirindividualorgans.Learntospellandidentifytheorgansinboldface.

Systems.

Digestive:

mouth,pharynx（throat）,esophagus,stomach,intestines（smallandlarge）,liver,gallbladder,pancreas

Urinaryorexcretory:

kidneys,ureters,urinarybladder,urethra.

Respiratory:

nose,pharynx,larynx（voicebox）,trachea（windpipe）,bronchialtubes,lungs

Reproductive:

female:

ovaries,fallopiantubes,uterus（womb）,vagina,mammaryglands,bartholingland（前庭球腺）;male:

testesandassociatedtubes,urethra,penis,prostategland,epididymis.epi'didimis,.seminalvesicle精囊腺bulbourethralgland,尿道球腺

Endocrine:

thyroidgland,pituitarygland,sexglands（ovariesandtestes）,adrenalglands,pancreas（isletsofLangerhans）,parathyroidglands

Nervous:

brian,spinalcord,nerves,andcollectionsofnerves.

Circulatory:

heart,bloodvessels（arteries,vains,andcapillaries）,inferiorcavalvein,superiorvenacava,lymphaticvesselsandnodes,spleen,thymusgland.

Musculoskeletal:

muscles,bones,andjoints

Skinandsenseorgans:

skin,hair,nails,sweatglands,sebaceous（oil）glands,eye,ear,nose,andgongue.

StudySection2

adiposetissueCollectionoffatcells

cartilageFlexibleconnectivetissueattachedtoboneatjoints.Forexample,itsurroundsthetracheaandformspartoftheexternalearandnose

epithelialcellSkincellsthatcovertheexternalbodysurfaceandlinetheinternalsurfacesoforgans.

HistologistSpecialistinthestudyoftissues

LarynxVoicebox;locatedattheupperpartofthetrachea

PharynxThroat.Thepharynxisthecommonpassagewayforfoodandair.

pituitaryglandEndocrineglandatthebaseofthebrain

thyroidglandEndocrineglandthatsurroundsthetracheaintheneck

tracheawindpipe

ureterOneoftwotubes,eachleadingfromasinglekidneytotheurinarybladder.Spellingclue:

Ureterhastwoe’sandtherearetwoofthem

urethraTubefromtheurinarybladdertotheoutsideofthe