Lab 7 580201 Frog Dissection ADA PDF

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BIOLOGY

Frog Dissection Investigation Manual

FROG DISSECTION Table of Contents 2

Overview

2 2

Outcomes Time Requirements

3 Background 6

Materials

7

Safety

9

Activity 1

10 Activity 2 11 Activity 3

Overview Dissectingafrogallowsstudentstobecomefamiliarwiththe basicstructurescommontovertebrateswhilelearningabout specificadaptationsthatallowfrogstoliveinsemi-aquaticenvironments.Thedevelopmentofspecificsystemscanbeexamined bycomparingthefrogtootherorganismssuchasfish,reptiles, andmammals.

Outcomes • Becomefamiliarwithdissectiontoolsandterminology. • Recognizetheinternalandexternalanatomiesofafrog. • Understandhowformaffectsfunction.

11 Activity 4 11 Activity 5

Time Requirements

12 Activity 6

Preparation ...................................................................... 5 minutes Dissection ..................................................................... 90 minutes

13 DisposalandCleanup

Key Personal protective equipment (PPE) goggles gloves apron

follow photograph stopwatch linkto resultsand required video submit

warning corrosion flammabletoxic environment healthhazard

MadeADAcompliantby NetCentric Technologies using theCommonLook® software

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Background FrogsaremembersoftheclassAmphibia. Amphibiansfirstemergedfromthewateronto landaround400millionyearsago.Theyare derivedfromagroupknownas“lobe-fin”fish. Thebonynatureofthesefishes’pectoralfins allowedthedevelopmentofweight-supporting forelimbs.Thedevelopmentoflungsfromthe fishes’swimbladdersallowedforfulltransitiontoterrestriallife.Theseorgansareusedfor densityregulationtoaidswimmingbyaquatic organisms,butastheancestorsofamphibians becamemoreterrestrial,theseorganstookon theroleofgasexchangethatwaspreviously handledbythegills.Whilefrogsmayspend largeamountsoftimeonland,theyrequiremoist environmentstomaintainhydration.Wateris alsonecessaryforreproduction,asfrogslayand fertilizetheireggsinwater. Frogsdonothavedirectdevelopmentlike mammals,reptiles,andbirds.Instead,frogs hatchintotadpoles,whichareconsidereda larvalform.Tadpolesbearverylittleresemblancetoadultfrogs.Theirmetamorphosis intotheadultformistriggeredbyhormonal changesproducedbythethyroidgland.The timingofmetamorphosisiscriticalintemperate regionsbecauseadultfrogscansurvivewinter buriedinmud,buttadpolescannot.Almost everyorganundergoeschangeduringmetamorphosis.Asthetailrecedes,thehindlimbs andforelimbsbegintodevelop.Cartilageis replacedbybone.Tadpolesarelargelyherbivorous,andastheydevelopintofrogs,theirteeth usedfortearingplantsdisappear,andthelarge intestineshortensastheneedtodigestfibrous plantmaterialsdecreases.Adultfrogs,which areprimarilycarnivorous,nolongerneedthese structures.Instead,thetonguemuscledevelops

toenableinsectcatching. Sensory Organs Theeyesofthefrogsithighontopofitshead, providingexcellentvisionwithawideangle ofview.Thiseyeplacementallowsfrogstolie submergedinthewater,hidingfrombothpredatorsandprey,andstillwatchtheirsurroundingswithonlytheireyesandnares (nostrils) exposed.Becausethetwoprimaryeyelidsare notverymobile,frogsrarelyclosetheireyes. Atransparentthirdlid,calledanictitating membrane,protectstheeyesfromdehydrating. Frogshaveanexternaleardrumcalleda tympanum.Theinnerearisprotectedfromthe frogs’owncallsbyamuscularmembrane.Frogs arecapableofmakingnoisessoloudthatthey canbeheardoveramileaway. Respiration Frogshavetworespirationpathways.Thefirstis throughtheskin;whencompletelysubmergedin water,gasescanbeexchangedthroughthethin, membranoustissue.Onland,mucusissecreted byglandsinthelowerlayeroftheskin(dermis). Frogsdonotpossessadiaphragmasmammals do.Inordertobreatheonland,afrogmust bringairintoitslungsbyloweringthefloorofits mouth,whichcausesthethroattoexpand.This createsnegativepressure,pullingairinthrough thenares,whichhaveanexternalopening andaninternalopeninginsidethemouth.The frogthenclosesthenaressothatairisforced intothelungswhenthethroatcontracts.The throatthenexpandsagain,drawingcarbon dioxide(CO2)-richairoutofthelungs. Thenthenaresarereopened,andtheairis continued on next page www.carolina.com/distancelearning

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FROG DISSECTION Background continued forcedoutbyanothercontractionofthethroat. This“two-stroke”processiscalledbuccal pumping. Feeding and Digestion Frogsareambushpredators.Theyremainvery stilluntilpreysuchasinsects,spiders,worms, orsmallfishapproach.Thenthemouthopens, andthetongueflicksout,grabbingthepreywith thetip,whichiscoatedwithastickymucus. Veryshortteetharelocatedontheupperjaw. Thevomerine teethareinthemiddleoftheroof ofthemouth,andthemaxillary teethareatthe sides;somespeciesusetheseforgrindingtheir food. Fromthemouth,foodpassesintotheesophagusbeforeitentersthestomach,whereit isbrokendownchemicallyandphysically. Movingoutofthestomach,foodtravelsinto thesmall intestine,wherechemicalandenzymaticdigestioncontinues.Theliver produces bile,adarkgreenoryellowishcollectionof digestivechemicalsandenzymesthathelps digestlipids.Bileisstoredinthegallbladder. Thepancreasproducesanothercollectionof enzymesandchemicalsthatdigestproteins, fats,andvitamins.Thehighconcentrationof bicarbonateionsalsohelpstoneutralizethe acidicgastricjuicefromthestomach.Bileand pancreaticjuiceflowintothecommonbileduct, thenintothesmallintestine,wherenutrients areabsorbed.Materialthatisnotabsorbedin thesmallintestinetravelstothelargeintestine, wherewaterisabsorbed,andthenoutthrough thecloaca,thecommonexcretoryopening

fortheurinary,digestive,andreproductive systems. Urinary System Thefunctionoftheurinarysystemistoclean wasteproductsoutoftheblood.Itconsistsof threemajororgans:thetwokidneysandthe bladder.Thekidneysfilterthefrog’sblood, removingwastes,salts,andwater.Thefrog’s urinarysystemmustbemoreflexiblethanthat ofamammaltoaccommodatethedifferent amountsofwatercomingintothebodywhen thefrogissubmergedversuswhenitisonland. Whenafrogissubmerged,itabsorbswater throughitsskin.Byadjustingtherateoffiltration atthekidney,amphibianscancontroltheirrate ofwaterloss.Frogkidneyspasswatertothe bladderwhenthefrogistakinginexcesswater. Whenthefrogisonland,muchofthewaste usuallydissolvedinurineiscarriedawaybythe renal portal system.Waterisalsoreabsorbed fromthebladder. Reproduction Assoonasmetamorphosisiscomplete,the firstspermcellsbegintodevelop.Maleswillbe readytoreproduceinaround1year.Females generallytakelonger,between2and3years. Matingisaccomplishedbyamplexus,where themalegraspsthefemalearoundthebelly anddepositshissperminthemassofeggsas shelaysthem.Thelevelofparentalcarevaries among species. Some species of frogs leave theireggsassoonastheyarelaidinthewater. Inotherspecies,oneoftheparents,frequently themale,maywatchovereggsuntiltheyhatch. continued on next page

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Midsagittal plane

Dissection Terminology Anatomistsandhealthcareprovidersuse veryspecificterminologythatenablesthemto preciselycommunicatetheirwork.Directional anatomicaltermsareusedtodescribethe relativepositionsofdifferentbodystructuresor toprovideinstructionsforincisionplacement. Directionaltermsareusedinthisandmost otherdissectionguides.Therefore,learning thesetermsisessentialforunderstandingand studyinganatomy.

Transverse plane

Midsagittal plane

Frontal plane

Transverse plane

Frontal plane

Direction or Plane

Definition

Superior

Above,towardthehead

Inferior

Below,towardthefeet

Anterior

Front,synonymouswithventralinbipedsandcranialinquadrupeds

Posterior

Back,synonymouswithdorsalinbipedsandcaudalinquadrupeds

Lateral

Towardtherightorleftside

Medial

Towardthemidline

Proximal

Nearortowardthepointofreference

Distal

Awayfromthepointofreference,whichisusuallytheattachmentpoint

Dorsal

Towardtheback

Ventral

Towardthebellyorabdomen

Cranial

“Towardthehead”

Caudal

“Towardthetail”

Superficial

Towardoralongthesurface

Deep

Asignificantdistancebelowthesurface

Rostral

Towardthenoseormouth

Sagittal plane

Dividesthebodyintolongitudinalleftandrightportions

Midsagittalplane

Dividesthebodyintoequalleftandrighthalves

Transverse plane

Perpendiculartothelongaxis,producescross-sections

Frontal plane

Dividesthebodyintodorsalandventralportions www.carolina.com/distancelearning

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FROG DISSECTION Materials Needed from the dissection kit:

Included in the materials kit:

Frog

Dissecting tray

Frogdissectionmat

Absorbent pad

Scissors

Forceps

Resealable bag

Ruler

Scalpel

Reorder Information: Replacement supplies forFrogDissection,itemnumber580201, canbeorderedfromCarolinaBiological SupplyCompany. Call: 800-334-5551toorder.

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Wooden probe

Safety Thisinvestigation requiressafetygoggles, disposablegloves,andalabapron. Followtheinstructionsforthisactivityclosely andobserveestablishedlaboratorysafetypractices,includingappropriatepersonalprotective equipment(PPE);safetygoggles,gloves,and labapronsmustbewornwhendissecting.Do noteat,drink,orchewgumwhileperformingthe dissection.Useproperhygienepracticesbefore, during,andafterthelab,includingwashingyour handsbeforeandafterperformingthedissection. Review pertinent portions of any Safety DataSheets(SDS)beforebeginningtheactivity. Keeppetsandchildrenawayfromlabmaterials andequipment. Dissections require special attention to safety. Pleasefollowtheseadditionalprecautions: •Cleanthecounterorworkspacethoroughly beforeandafterthedissection,usingisopropyl alcohol(orothernon-bleachdisinfectant). Isopropylalcohol(rubbingalcohol) isflammable.Keepawayfromopen flameifusingalcoholasdisinfectant. •Washyourhandsthoroughlywithsoapand waterbeforeandafterthedissection. •Onlyperformthedissectiononthedissecting tray.Thiswillcontainboththespecimenand anyexcessfluids. •Spreadtheabsorbentpadblue-sidedown underneaththetraytocaptureanyspilledfluid. •Ingeneral,scissorsareusedmorefrequently thanthescalpel,especiallywhencaremustbe takennottocuttoodeeplyintothespecimen.

CuttingaSpecimen h  ttp://players.brightcove. net/17907428001/HJ2y9UNi_default/index. html?videoId=4573445864001 •Scalpelsareusedinfrequentlyinmost dissectionlabsandrequirespecialhandling anddisposal: -Nevercuttowardyourholdinghandand fingers. -Cutinadownwardmotionusingasteady, even pressure. -Alwaysuseasharpblade. -Donotuseascalpelthatisnicked,bent,or damaged. -Donotuseascalpeltocutthroughboneor heavycartilage. -Neveruseascalpelforanythingotherthan dissection. -Donotuseascalpeltocutthroughboneor heavycartilage. -Neveruseascalpelforanythingotherthan dissection. Using a Scalpel http://players.brightcove. net/17907428001/HJ2y9UNi_default/index. html?videoId=5170128655001 Carolina’s Perfect Solution® Independent,certifiedlaboratoryanalysesof specimensfixedinCarolina’sPerfectSolution® havefoundthatitisnontoxicanddoesnotgive offdangerousfumes.Thismeansthat,forsafety purposes,useofCarolina’sPerfectSolution® specimensdoesnotrequirespecializedventilation.Carolinadoesrecommendperforming thedissectioninawell-ventilatedroomwith continued on next page

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FROG DISSECTION Safety continued someactiveventilationwhenworkingwithany preservedspecimens.Forahomesetting,this mayincludeopeningwindowsandturningona ceilingfan.ThesafenatureofCarolina’sPerfect Solution®alsomeansthatinmostlocalitiesthere arenomandateddisposalrequirements. Carolina’sPerfectSolution® causes mildskinirritationifsuitablePPEis notworn.Avoidcontactwithskinand eyes.Donotingestspecimen,especiallyifyou areormaybecomepregnant. Storage of Specimens Ifitisnecessarytostorethespecimenbetween workperiods,youmaychoosetoplaceitinthe plasticstoragebagwithasmuchoftheoriginal solutionaspossible.Establishinganairtight sealisthebestwaytoretainspecimenintegrity andpreventdryingoutofthespecimen.First, squeezeasmuchairoutofthespecimenbag aspossiblebeforesecuringtheopeningwitha rubberband,tape,orabinderclip.Afterclosing thebag,thespecimencanbestoredinalarger, airtightboxorbagatroomtemperature.

8 CarolinaDistanceLearning

ACTIVITY ACTIVITY 1 A External Anatomy 1. L  aythefrogdorsalsurfaceupinthe dissectiontray. 2.  Takeaphotoofthedorsalsideofthe  frog.Noticethethinnessofthefrog’s skin(5)andtheabsenceofscales,hair,or anyotherprotectivecovering. Numbersinparentheses()refertoyour includeddissectionmat. 3. 

Takeaphotoofthehead.Locatethe external nares(1),ornostrils.

4. T  heeyes(2)areeasytofind.Closely examineeacheyeandlocatethenictitating membrane,athirdeyelid.Inlivingfrogs,the nictitatingmembranesaretransparentand covertheeyeswhentheanimalisunderwater. 5. J  ustposteriortotheeyesarelarge,circular areasknownasthetympanic membranes (7),oreardrums.Nearthecenterofeach tympanicmembraneisaraisedareathat markstheattachmentofasmallbone,the columella,tothemembrane.Thisbone transmitsvibrationstotheauditorynerve. 6. L  ocatetheshoulder,elbow,andwristjoints oftheforelimbs.Countthedigitsoneach forelimb.Theinnermostdigitofmalefrogshas aswollenpadduringthebreedingseason.

9. G  entlyprythemouthopenandusescissors tocutthejawsatthejoints.Examinethe insideofthemouth.RefertoFigure1. Figure 1. Internal nares Vomerine teeth

Maxillary teeth

Esophageal opening (gullet)

Eustachian tubeopening

Opening to vocal sac

Glottis

10.   Takeaphotooftheinsideofthe   mouth.Findthetongue(6)andnote anyunusualcharacteristicsyouobserve. 11. D  irectlybehindthetongue,locatearaised structurewithaslitinit.Thisistheglottis, theopeningoftheairpassagewaythatleads fromthemouthtothelungs(15),which willbevisiblewhenviewingthecirculatory system.Behindtheglottisistheopeningof theesophagus.

7. N  eartheendofthebodyontheventralside ofthefrog,istheopeningofthecloaca. Feces,urine,andreproductivecellsare expelledthroughthecloaca.

12. F  indtwobonyknobsprojectingfromthe uppersurfaceofthemouth.Thesearethe vomerine teeth(8).Ifyourubyourfinger alongtheinsideofthejaw,youwillfeelthe maxillary teeth (4).

8. E  xaminethemuscularhindlimbs.Locatethe hip,knee,andanklejoints.Examinethewebsof eachfoot.Countthedigitsoneachhindlimb.

13. N  earthevomerineteetharetheinternal nares(3),theinternalopeningsofthe continued on next page www.carolina.com/distancelearning

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ACTIVITY

nostrils.Musclesattachedtosmallbones canopenandclosethenares’passageways. 14. T  heopeningsoftheEustachiantubesare locatednearthecornersofthemouth.Insert adissectingprobeintooneopening,push carefully,andobservewheretheneedle comes out. 15. T  wolarge,muscularpadsarefoundinthe roofofthemouth.Thefrogretractsitseyes intothesepadswhenitblinks.

2. W  iththeforceps,liftandmakeanincision throughtheabdomenmuscles.Usethepoint ofapairofscissorstomakethecutsshown inFigure3.Itwillbenecessarytocutthe bonesofthepectoralgirdlewithscissors. Makethecutscarefullytoavoiddamaging theinternalorgans. Figure 3. Cutbones here

ACTIVITY 2 A Internal Anatomy 1. L  aythefrogventralsurfaceuponthe dissectiontray.Usingtheforceps,lifttheskin overthefrog’sabdomen,insertthepointof apairofscissors,andmakethecutsshown inFigure2.Whenthecutsaremade,liftone corneroftheskinwiththeforcepsanduse thescalpelandscissorstoseparatetheskin fromtheunderlyingmuscles.Completelycut awaytheskinfromtheabdomenandthroat. Figure 2.

10 CarolinaDistanceLearning

3. Foldbackthebodywallandcutitoffto  exposetheinternalorgans. 4. Ifyourfrogisafemale,theoviductmaybe enlargedwitheggsandmaypartiallycover thedigestiveorgans.Ifthisisthecase, carefullycutawaytheoviductandremove enoughoftheeggstoclearlyseetheinternal organs.

ACTIVITY 3 A Digestive System 1.  Takeaphoto.Youmayneedtotake  additionalphotosinordertoshowall oftheorgansinthissection.Attheanteriorof theabdominalcavityistheliver (14),alarge, brownglandwiththreelobes.Liftthelobes oftheliverandsearchforadark,greenish sac.Thissacisthegallbladder(10).The greencolorisduetoapigmentinthebile, whichisaliversecretionthatisstoredinthe gallbladder. 2. T  heJ-shaped,muscularsacpartiallybeneath theliverontheleftsideofthefrog’sbodyis thestomach(22)(leftandrightrefertothe frog’sleftandright).Thelowerendofthe stomachattachestothesmall intestine (20). Twodivisionsmakeupthesmallintestine; theduodenumisthelessfoldedportionthat attachestothelowerendofthestomach, andtheileumisthehighlyfoldedportion.The smallintestineandtheotherinternalorgans areheldinplacebymembranescalledthe mesenteries(16).Noticethatthedigestive organsareattachedtonumerousblood vessels. 3. L  ookbetweenthestomachandduodenumto findthepancreas,along,thinmassoftissue inthemesenterybetweenthetwoorgans. 4. L  ifttheileumandfindthespleen(21),a somewhatroundorganthatisbrownincolor. Thespleenisactuallypartofthecirculatory system.Follow...