what happens when you die?

Click here to load reader

Post on 23-Feb-2016

48 views

Category:

Documents

0 download

Embed Size (px)

DESCRIPTION

What happens when you die?. Introducing the Mortis Brothers. The Chemistry of Death. Rigor Mortis. Skeletal muscles partially contract Joints stiffen, lock in place Onset is 10 minutes to several hours Rapid cooling can delay it Lasts up to 72 hours. Chemistry of Rigor Mortis. - PowerPoint PPT Presentation

TRANSCRIPT

Introducing the Mortis Brothers

What happens when you die?Introducing the Mortis BrothersThe Chemistry of DeathRigor MortisSkeletal muscles partially contractJoints stiffen, lock in placeOnset is 10 minutes to several hoursRapid cooling can delay itLasts up to 72 hoursChemistry of Rigor MortisLiving muscle cells use oxygen to burn glycogenAfter death no oxygenanaerobic glycolysis makes lactic and pyruvic acids Faster than aerobic but only produces 2 ATP vs 38 ATPpH falls as acidity increases shutting off enzymesAcid promotes a reaction between actin and myosin which work together to contract the muscleMuscle shortens until all ATP and acetylcholine is used upMuscle Contraction

Ca and ATP Ratchet the Fibers

http://www.ebsa.org/npbsn41/intro_muscle.htmlHastening RigorAnything that depletes ATP will hasten rigorStrenuous exercise just before deathSevere convulsionsHigh feverCadaveric SpasmInstantaneous onset of rigor

Forensic Pathology, Second EditionBy Dominick DiMaio, Vincent J.M. DiMaioEnd of Rigor MortisThe muscles relax when the body starts to decompose and the fibers begin to break downIntracellular digestive enzymes are released from the lysosomes as the cells begin to disintegrate, destroying the muscle fibers (autolysis)Meat is more tender after rigor mortis has passed (Aged Beef?)Temperature Dependence of Rigor Mortis

Rigor depends on: the type of muscle fibersTemperatureStiffen faster at higher temperatureStudies of rigor development in ratshttp://www.geradts.com/anil/ij/vol_003_no_002/papers/paper001/002.gifFull Rigor

As foundAfter rolling the bodyLivor MortisHeart stops beating which had been mixing bloodRed blood cells are denser so they sinkMaroon to blue color develops at lowest pointsVisible 30 minutes-2 hours after deathTells you if the body was moved.Livor MortisSoon after death, blood is still in vessels, so pressure on an area pushes the bood outget blanching up to approximately 4 hours after deathAs time goes on blood vessels break down as do blood cells and hemoglobin break down pigment moves out into the tissuesNo more blanchingPressure or constrictive clothing prevents blood from pooling locallyContact pallorLivor Mortis

Livor MortisAfter death cells release enzyme (fibrinolysins) that prevents clottingBlood in body stays liquid after deathPermanently wont clot 30-60 minutes after deathAlgor MortisBody cools by Radiation (the higher the body temperature the more heat lost)Conduction depends on surface contactfaster if in water because enhanced contactConvectionWind cools fasterRate of cooling of body after death1.5 F per hour under normal conditionsNo real conditions are normal

Algor MortisAmbient temperatureNewtons Law of Cooling

T is body temperature, t is timeThe bigger the temperature difference, the faster the cooling rateOutdoors, temperature varies a lotmust correct formula by varying Tambient

Algor MortisIf ambient temperature is constant, Newtons Law of Cooling is easy to solveMeasure temperature at two different times without moving the body to find k

Algor Mortis

Algor MortisClothing Insulates body from heat lossObesityFat insulates, temperature falls more slowlyRatio of surface area to volumeChildren, thin people cool fasterIn water?Cooling is faster since water is a better conductor of heat than air

Approximate Times for Algor and Rigor Mortis.

Algor MortisNew issueIs there a plateau before body temperature starts to fall after death?May be up to several hoursAnaerobic cellular chemistry continues after deathCellular chemistry releases energy as heat

Testing Potassium Levels in the Eye to Determine Time of DeathK concentration is higher inside cells by up to 40X during lifeIt takes energy (ATP) to maintain the difference

Maintaining Concentration Differences in a Living CellPotassium in Ocular FluidAt death, no more ATP formation (energy storage molecule)K diffuses out of cells at a constant rate, into fluid inside the eyeTime of death

Most accurate in first 12 hours after deathSupposedly independent of temperature

Determining Long Post Mortem IntervalsDecomposition occurs in stagesInitial Decay (0-3 days)Autolysis--bodys own enzymes destroys tissueBegins immediatelyPutrefaction (4-10 days)Bacteria in gut leak outAnaerobic conditionsBloat from hydrogen sulfide, methane, cadaverine, putrescine released

The Smell of Death

putrescinecadaverineBreakdown products from amino acids ornithine and lysineAmino acid loses CO2H = white C = turquoise N = blueDetermining Long Post Mortem IntervalsBlack Putrefaction (10-20 days)Body collapsesLiquid seeps into the soilButyric Fermentation (20-50 days)Cheesy smell from butyric acidMaggots leaveBeetles arriveDry decay (beyond 50 days)Hair is consumed by moths and mitesBones are left

Longer Term Estimates of Time of DeathMonitoring ratios of body decay products in the soil

Dr. ArpadVass, ORNL

The Body FarmU. Tenn.

The first well controlled experiments to explore decompositionVolatile Fatty AcidsBreakdown Products of Fat

Red= OTurquoise=CWhite = HPropionic (3C)n-butyric (4C in a row)i-butyric (4C branched)n-valeric (5C in a row)i-valeric (5C branched)Parmesan cheeseRancid butterStinky feetVomitOld cheeseRancid Swiss cheeseHydrolysis of Fat

Red= OTurquoise=CWhite = H

Fat + 3 WaterGlycerol + 3 Fatty AcidsIdentifying Small MoleculesGas chromatographyPresumptive testGas chromatography + mass spectrometryDefinitive testWe will discuss these techniques in detail later in the course!

Volatile Fatty Acid AnalysisResults from the Body FarmDepends on temperatureThe hotter, the faster the reactions proceedAccumulated Degree Days (sum average daily temp)Decay is linear in Accumulated Degree DaysDepends on whether body was buried or notDecay is faster on the surfaceMore insect activityWarmer2 feet down is fairly constant 50-55o FDecay is slower in acid soilPine forests have very acid soilDecay is slower if the body is sprayed with insecticide

AdipocereGrave WaxOn bodies are not exposed to insectsRequires moist anaerobic environment (drowning)Hydrolysis of fat to fatty acids and soaps in presence of bacterial enzymesBasic conditions enhance formationProminent on cheeks, buttocks, stomach, breastsResistant to bacteriaSlows further decompositionOtzi, the Ice Man5300 year old bodyFound by hikers in Austrian AlpsOtzi is primarily now adipocere

www.spectroscopynow.com/.../MS_Feb08_otzi.jpg Forensic EntomologyBlow flies lay eggs within minutes of deathThere are a succession of insects that will infest the body at different points after death

http://ysp.ucdavis.edu/research/WongB/default_files/image003.jpgLucilia sericataForensic EntomologyEstimating time of death from lifecycle of insectsInsect life cycle also should be timed in accumulated degree hours to account for temperature

http://www.brazoria-county.com/sheriff/id/bugs/blowfly_lifecycle_pic.htm

Life Cycle of the Blowfly

Maggots are cold blooded and take longer to hatch and grow in cooler temperatures.http://www.nhm.ac.uk/nature-online/life/insects-spiders/fathom-maggot/assets/22feat_maggots_and_murders.pdfTemperature Dependence of Life Cycle of Lucilia sericata Temp(C) Egg (hrs)Larva 1st Instar (hrs) Larva 2nd Instar (hrs)Larva 3rd Instar (hrs)Pre-pupa (hrs)Pupa (hrs)Total time (days) 16 (61 F)41 53 42 98 148 393 32 21 (70 F)21 31 26 50 118 240 20 27 (81 F)18 20 12 40 90 168 14 Dormancy IssuesMost insects go dormant (stop growing) below a certain critical temperature Td6 C for cold tolerant insects10 C for cold intolerant insectsUsually you subtract off the dormant temperature when calculating ADD or ADH(Tav Td )number of hoursForensic EntomologyDetermine temperature history at crime sceneGet hourly records from nearest weather stationSet up weather station at crime scene to estimate accuracy of weather station dataRear maggots from body to adulthood in lab to determine speciesCan also use DNA to identify species if DNA library is availableEstimate backwards to estimate age of maggots when foundThen knowing life cycle, estimate backwards to date of egg laying correcting for temperature effectsDo it for each species of insect found

Forensic EntomologyConsider behavorial factors affecting ovipositionDoes the species lay eggs at night?Does the species lay eggs in the rain?Does the species fly in high winds?Is it active only above a certain temperature?Is it attracted to sunlight or shade?Would coverings or burial keep the flies from getting to the body?Is the maggot mass so large it is hot?

Succession of FaunaBacteria (body is acidic from lactic acid)Blow fly eggs/larvae (body becomes basic)Beetles that feed on larvaeParasitic wasps lay eggs in larvae and pupaeCheese flies and coffin flies arrive as body dries and blow flies leaveHide beetles, carcass beetles eat ligaments and dry fleshMoth larvae and mites consume hair

http://www.deathonline.net/decomposition/corpse_fauna/index.htmPost Mortem Time Line

What methods can you use? Which will be the most accurate?Introducing the Mortis BrothersThe Chemistry of DeathBody Temp7298.67296.80167560957295.12492906167293.56154094287292.10384752277290.74470318657289.47744540717288.29586208537287.19416109847286.16694190687285.20916908097284.31614761717283.48349992327282.7071443593

Ambient TBody TTime Since Death (hrs)Body Temperature (F)

Sheet1Time (hrs)Ambient TInitial Body TkBody T07298.60.0798.617298.60.0796.801675609527298.60.0795.124929061637298.60.0793.561540942847298.60.0792.103847522757298.60.0790.744703186567298.60.0789.477445407177298.60.0788.295862085387298.60.0787.194161098497298.60.0786.1669419068107298.60.0785.2091690809117298.60.0784.3161476171127298.60.0783.4834999232137298.60.0782.7071443593

Sheet2

Sheet3

Bo

View more