Unit 8 – Decomposition & Human Remains Mrs. Teates Forensic Science Newport High School. Unit 8 – Decomposition & Human Remains Mrs. Teates Forensic Science Newport High School 2. Lesson 1 – Stages of Death Lesson Essential Questions: – What are the stages of death? Vocabulary: Algor mortis, glaister equation, livor mortis, rigor mortis, autolysis, putrefaction, adipocere, saponification, diagenesis 3. Rigor Mortis Skeletal muscles partially contract Joints stiffen, lock in place Onset is 1. Rapid cooling can delay it Lasts up to 7. Chemistry of Rigor Mortis Living muscle cells use oxygen to burn glycogen After death no oxygen—anaerobic glycosis makes lactic and pyruvic acids p. H falls as acidity increases Acid promotes a reaction between actin and myosin which work together to contract the muscle Muscle shortens until all ATP and acetylcholine is used up 5. Muscle Contraction 6. End of Rigor Mortis The muscles relax when the body starts to decompose and the fibers begin to break down Intracellular 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?) 7. Temperature Dependence of Rigor Mortis Rigor depends on: the type of muscle fibers Temperature Stiffen faster at higher temperature Studies of rigor development in rats http: //www. Livor Mortis Heart stops beating which had been mixing blood Red blood cells are denser so they sink Maroon to blue color develops at lowest points Visible 3. Tells you if the body was moved. Livor Mortis Soon after death, blood is still in vessels, so pressure on an area pushes the bood out As time goes on blood vessels break down as do blood cells and hemoglobin break down pigment moves out into the tissues Pressure or constrictive clothing prevents blood from pooling locally – Contact pallor 1. Livor Mortis 1. After death cells release enzyme (fibrinolysins) that prevents clotting Blood in body stays liquid after death – Permanently won’t clot 3. Algor Mortis Body cools by – Radiation (the higher the body temperature the more heat lost) – Conduction depends on surface contact faster if in water because enhanced contact – Convection Wind cools faster Rate of cooling of body after death – 1. F per hour under “normal conditions” – No real conditions are “normal” 1.
Algor Mortis Ambient temperature – Newton’s Law of Cooling T is body temperature, t is time The bigger the temperature difference, the faster the cooling rate Outdoors, temperature varies a lot—must correct formula by varying T ambient 1. Algor Mortis If ambient temperature is constant, Newton’s Law of Cooling is easy to solve Measure temperature at two different times without moving the body to find k 1. Algor Mortis 1. Clothing – Insulates body from heat loss Obesity – Fat insulates, temperature falls more slowly Ratio of surface area to volume – Children, thin people cool faster In water? Cooling is faster since water is a better conductor of heat than air 1. Approximate Times for Algor and Rigor Mortis. Full text of 'The Times News (Idaho Newspaper) 1965-06-25' See other formats. Download Blood Out torrent from movies category on Isohunt. Torrent hash: 9ee1f379278719fb2dac53638e36dd0072936f35. bood-out_arc.avi Download from Movies. Title: The Irish Volunteer - Volume 1 - Number 42, Author: An Phoblacht, Name: irish-vol-1-42-med, Length: 16 pages, Published: 2014-11-21T00:00:00.000Z. He would've been bood out of the reunion show! permalink; embed. Similarly, Savage's story arc is fantastic, though shorter than many of the other's on the list. Unit 8 – Decomposition & Human Remains Mrs. Teates Forensic Science Newport High School. Published byWesley Mallison Modified about 1 year ago. Algor Mortis New issue – Is there a plateau before body temperature starts to fall after death? May be up to several hours – Anaerobic cellular chemistry continues after death – Cellular chemistry releases energy as heat 1. Testing Potassium Levels in the Eye to Determine Time of Death K concentration is higher inside cells by up to 4. X during life It takes energy (ATP) to maintain the difference 2. Maintaining Concentration Difference in a Living Cell 2. Potassium in Ocular Fluid At death, no more ATP formation (energy storage molecule) K diffuses out of cells at a constant rate, into fluid inside the eye Time of death Most accurate in first 1. Supposedly independent of temperature 2. Determining Long Post Mortem Intervals Decomposition occurs in stages – Initial Decay (0- 3 days) Autolysis- -body’s own enzymes destroys tissue Begins immediately – Putrefaction (4- 1. Bacteria in gut leak out Anaerobic conditions Bloat from hydrogen sulfide, methane, cadaverine, putrescine released 2. The Smell of Death putrescine cadaverine Breakdown products from amino acids ornithine and lysine Amino acid loses CO 2 H = white C = turquoise N = blue 2. Determining Long Post Mortem Intervals – Black Putrefaction (1. Body collapses Liquid seeps into the soil – Butyric Fermentation (2. Cheesy smell from butyric acid Maggots leave Beetles arrive – Dry decay (beyond 5. Hair is consumed by moths and mites Bones are left 2. Longer Term Estimates of Time of Death Monitoring ratios of body decay products in the soil Dr. Arpad Vass, ORNL The Body Farm U. Tenn. The first well controlled experiments to explore decomposition 2. Identifying Small Molecules Gas chromatography – Presumptive test Gas chromatography + mass spectrometry – Definitive test We will discuss these techniques in detail later in the course! Volatile Fatty Acid Analysis Results from the Body Farm Depends on temperature – The hotter, the faster the reactions proceed – Accumulated Degree Days (sum average daily temp) – Decay is linear in Accumulated Degree Days Depends on whether body was buried or not – Decay is faster on the surface More insect activity Warmer—2 feet down is fairly constant 5. F Decay is slower in acid soil – Pine forests have very acid soil Decay is slower if the body is sprayed with insecticide 2. Adipocere—Grave Wax On bodies are not exposed to insects Requires moist anaerobic environment (drowning) Hydrolysis of fat to fatty acids and soaps in presence of bacterial enzymes Basic conditions enhance formation Prominent on cheeks, buttocks, stomach, breasts Resistant to bacteria – Slows further decomposition 2. Otzi, the Ice Man 5. Found by hikers in Austrian Alps Otzi is primarily now adipocere www. MS_Feb. 08_otzi. jpg 3. The Process of Death, continued Stage. Description Initial or fresh decay (autolysis) The cadaver appears fresh externally but is decomposing internally due to the activities of bacteria present before death (0–4 days). Putrefaction or bloating The cadaver is swollen by gas produced internally, accompanied by the odor of decaying flesh (4–1. Black putrefaction Flesh of creamy consistency, with exposed body parts black. Body collapses as gases escape. Fluids drain from body. Odor of decay very strong (1. Butyric fermentation Cadaver drying out. Some flesh remains at first; cheesy odor from butyric acid (2. Dry decay (diagenesis) Cadaver almost dry; slow rate of decay. May mummify (5. 0–3. Summary of Stages of Death 3. F – internal body temperature 1. Hours since death = The Process of Death Algor Mortis: Body cooling rate Livor Mortis: skin discoloration caused by pooling of blood Rigor Mortis: rigidity of skeletal muscles A pathologist estimates time of death from these factors. Temperature of body. Stiffness of body. Time since death Warm. Not stiff. Not dead more than 3 hours Warm. Stiff. Dead between 3 and 8 hours Cold. Stiff. Dead between 8 and 3. Cold. Not stiff. Dead for more than 3. Summary of Decomposition 3. Lesson 2 – Forensic Entomology Lesson Essential Questions: – How is the life cycle of insects important in determining the time of death? How do insects play a role in decomposition? Vocabulary: Metamorphosis, molt, instar, oviposition, ambient, mites, eclosion, degree- day, puparia 3. Taxonomy Classification of Things in an Orderly Way We are interested in the phylum, Arthropoda; class, Insecta; order: Diptera (flies) Coleoptera (beetles) 3. Forensic Entomology Entomology is the study of insects. Forensic entomology involves the use of insects and other arthropods to aid in legal investigation There are three areas of application: Insect damage to structures Infestation of foodstuffs Insects that inhabit human remains 3. Life Cycle of Insects Metamorphosis egg larva (maggot) pupa winged adult The life cycle of Musca domestica 3. Insects arrive at a decomposing body in a particular order (succession) and then complete their life cycle based on the surrounding temperature. By collecting and studying the types of insects found on a body and their metamorphic stage, a forensic entomologist can estimate the time of death. Time of Death 3. Accumulated Degree Hours and Days Accumulated degree hour (ADH): a given amount of thermal energy needed to develop from one stage of an insect life cycle to the next Degree day – amount of development that occurs in 2. Accumulated degree day (ADD): a given amount of days that an insect requires to complete its development. Unique to different species of insects ADH and ADD are calculated from temperature data. Calculating ADD 1. Calculate the mean (average) temperature for that day. Compare the mean to the organism’s lower developmental threshold. If the mean is three degrees higher than the lower developmental threshold, then there have been three degree- days. Developmental thresholds need to be looked up for individual insects.) 3. Calculating ADH Calculate degree days and then multiple by 2. This is an approximate value. Insects of Death Diptera First to arrive Then Blowflies Flesh flies Houseflies Flies can arrive within minutes. They lay eggs that hatch to maggots. Maggots feed on soft, mushy body parts. More insects arrive to feed on the body and each other. Insects of Death, continued Coleoptera In rough order of appearance, from within hours to dry decay: Rove beetle.
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