Topic 5 &6

• What are the factors that are involved in Time of death?

  • Decomposition
  • Stage of Succession
  • Rigor Mortis
  • Body Temperature
  • Forensic Entomology
• Body Temperature?

  After a person Dies their core temp will resolve down to the ambient temperature. As the body decreases by 1.5 - 2 degrees every hour after death. So we can use a sigmoid curve to approx a time of death
• How to measure body temperature?

  1. Abdominal Stab
  2. Rectal temperature
• Rigor Mortis?After death After death muscles begin to stiffen as ATP is used up, calcium ions build up in the muscle cells and they become fixed in a state of contraction. The extent of rigor mortis can be used to determine time of death
• Rigor Mortis?

  After death muscles use up all remains oxygen till oxygen depletion leading to anaerobic conditions begins to stiffen as ATP is used up, then after a while lactic acid causes pH to drop and inhibits production of enzymes needed for respiration and then ATP is no longer produces then they become fixed in a state of contraction due to myosin and actin need this to relax. But then as the body starts to decompose muscles relax. The extent of rigor mortis can be used to determine time of death.
• What can affect Rigor Mortis?

  Body mass - storage of oxygen

  Temperature- change nature of enzyme activity
• What can affect body temperature?

  1. Body Position such as foetal conserves heat
  2. Wind conditions
  3. Clothing
• Decomposition?

  1. Autolysis- break down of cells
  2. Breaking down of cells leads to excretion of enzymes further breaking down surrounding tissue
  3. Bacteria in the gut then can break down further cells
  4. Putrefaction production of sulphaemoglobin
  5. Bloating where the decomposing bacteria starts to explode due to overgrowth as gases are produced such as ammonia, carbon dioxide
  6. This then leads to succession of organisms that colonise the body when at optimal living conditions.