Objective: SWBAT use the evidence of livor mortis, rigor mortis, and algor Objective: SWBAT use the evidence of livor mortis, rigor mortis, and algor mortis to calculate the approximate time of deathmortis to calculate the approximate time of death

Do Now:

Review GameReview Game

Purpose: Be able to guess your Purpose: Be able to guess your word(s) by using only minimal cluesword(s) by using only minimal clues

Round 1: charades (no talking)Round 1: charades (no talking) Round 2: one wordRound 2: one word Round 3: definition or example Round 3: definition or example

Introducing the Mortis Introducing the Mortis BrothersBrothers

The Chemistry, Math and The Chemistry, Math and Biology of DeathBiology of Death

Rigor MortisRigor Mortis

Skeletal muscles partially contractSkeletal muscles partially contract Joints stiffen, lock in placeJoints stiffen, lock in place Onset is 10 minutes to several hoursOnset is 10 minutes to several hours Rapid cooling can delay itRapid cooling can delay it Lasts up to 72 hoursLasts up to 72 hours

Chemistry of Rigor MortisChemistry of Rigor Mortis

Living muscle cells use oxygen to burn Living muscle cells use oxygen to burn glycogenglycogen

After death no oxygen—anaerobic glycosis After death no oxygen—anaerobic glycosis makes lactic and pyruvic acidsmakes lactic and pyruvic acids

pH falls as acidity increasespH falls as acidity increases Acid promotes a reaction between actin and Acid promotes a reaction between actin and

myosin which work together to contract the myosin which work together to contract the musclemuscle

Muscle shortens until all ATP and Muscle shortens until all ATP and acetylcholine is used upacetylcholine is used up

Exit TicketExit Ticket

In 4-5 full, complete sentencesIn 4-5 full, complete sentences

Give a definition of rigor mortis, livor Give a definition of rigor mortis, livor mortis, and algor mortis. How does mortis, and algor mortis. How does this relate to calculating the manner, this relate to calculating the manner, cause, mechanism or time of death.cause, mechanism or time of death.

BRING YOUR CALCULATORS FOR BRING YOUR CALCULATORS FOR THURSDAY!!!THURSDAY!!!

Muscle ContractionMuscle Contraction

Ca and ATP Ratchet the Ca and ATP Ratchet the FibersFibers

End of Rigor MortisEnd of Rigor Mortis

The muscles relax when the body The muscles relax when the body starts to decompose and the fibers starts to decompose and the fibers begin to break downbegin to break down

Intracellular digestive enzymes are Intracellular digestive enzymes are released from the lysosomes as the released from the lysosomes as the cells begin to disintegrate, destroying cells begin to disintegrate, destroying the muscle fibers the muscle fibers (autolysis)(autolysis)

Meat is more tender after rigor mortis Meat is more tender after rigor mortis has passed (Aged Beef?)has passed (Aged Beef?)

Livor MortisLivor Mortis

Heart stops beating which had been Heart stops beating which had been mixing bloodmixing blood

Red blood cells are denser so they sinkRed blood cells are denser so they sink Maroon to blue color develops at Maroon to blue color develops at

lowest pointslowest points Visible 30 minutes-2 hours after deathVisible 30 minutes-2 hours after death Tells you if the body was moved.Tells you if the body was moved.

Livor MortisLivor Mortis

Soon after death, blood is still in vessels, so Soon after death, blood is still in vessels, so pressure on an area pushes the bood out—pressure on an area pushes the bood out—– get blanching up to approximately 4 hours after get blanching up to approximately 4 hours after

deathdeath As time goes on blood vessels break down As time goes on blood vessels break down

as do blood cells and hemoglobin break as do blood cells and hemoglobin break down pigment moves out into the tissuesdown pigment moves out into the tissues– No more blanchingNo more blanching

Pressure or constrictive clothing prevents Pressure or constrictive clothing prevents blood from pooling locallyblood from pooling locally– Contact pallorContact pallor

Livor MortisLivor Mortis

Livor MortisLivor Mortis

After death cells release enzyme After death cells release enzyme (fibrinolysins) that (fibrinolysins) that preventsprevents clotting clotting

Blood in body stays liquid after deathBlood in body stays liquid after death– Permanently won’t clot 30-60 minutes Permanently won’t clot 30-60 minutes

after deathafter death

Algor MortisAlgor Mortis

Body cools by Body cools by – Radiation Radiation

(the higher the body temperature the more heat lost)(the higher the body temperature the more heat lost)

– Conduction depends on surface contactConduction depends on surface contact faster if in water because enhanced contactfaster if in water because enhanced contact

– ConvectionConvection Wind cools fasterWind cools faster

Rate of cooling of body after deathRate of cooling of body after death– 1.5 1.5 °°F per hour under “normal conditions”F per hour under “normal conditions”– No real conditions are “normal”No real conditions are “normal”

Algor MortisAlgor Mortis

Ambient temperatureAmbient temperature– Newton’s Law of CoolingNewton’s Law of Cooling

T is body temperature, t is timeT is body temperature, t is time The bigger the temperature difference, the The bigger the temperature difference, the

faster the cooling ratefaster the cooling rate Outdoors, temperature varies a lot—must Outdoors, temperature varies a lot—must

correct formula by varying Tcorrect formula by varying Tambientambient

( )( ( ) )ambient tT k T t Tt

Algor MortisAlgor Mortis

If ambient temperature is constant, If ambient temperature is constant, Newton’s Law of Cooling is easy to Newton’s Law of Cooling is easy to solvesolve

Measure temperature at two Measure temperature at two different times without moving the different times without moving the body to find kbody to find k 0( ) ( ) kt

ambient ambientT t T T T e

Algor MortisAlgor Mortis

70

80

90

100

0 2 4 6 8 10 12 14Time Since Death (hrs)

Bo

dy

Tem

per

atu

re (

F)

Ambient T

Body T

Algor MortisAlgor Mortis

Clothing Clothing – Insulates body from heat lossInsulates body from heat loss

ObesityObesity– Fat insulates, temperature falls more Fat insulates, temperature falls more

slowlyslowly Ratio of surface area to volumeRatio of surface area to volume

– Children, thin people cool fasterChildren, thin people cool faster In water?In water?

– Cooling is faster since water is a better Cooling is faster since water is a better conductor of heat than airconductor of heat than air

Algor MortisAlgor Mortis

New issueNew issue– Is there a plateau before body Is there a plateau before body

temperature starts to fall after death?temperature starts to fall after death?– May be up to several hoursMay be up to several hours– Anaerobic cellular chemistry continues Anaerobic cellular chemistry continues

after deathafter death– Cellular chemistry releases energy as Cellular chemistry releases energy as

heatheat