An elderly man is found dead in his car with the windows down. He has been missing for 2
days. The average temperature has been 36 degrees F. How would these factors affect lividity
and rigor mortis rates?
O lividity - increases / rigor - increases
O lividity - decreases / rigor - decreases
O lividity - decreases / rigor - unaffected
O lividity - decreases / rigor - increases

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UpStudy AI · Accepted Answer

**Step 1. Effects on Postmortem Lividity**

- **Lividity (livor mortis)** is the settling of blood due to gravity.
- The rate and intensity of lividity depend largely on the fluidity of blood and the rate at which blood settles in dependent areas.
- **Cold temperatures $$(36^\circ F)$$** cause the blood to become more viscous. As a result, the gravitational pooling is less efficient even though lividity still occurs.
- Thus, in a colder environment, the *intensity or rate* of lividity formation is decreased compared to a warmer environment.

**Step 2. Effects on Rigor Mortis**

- **Rigor mortis** is the stiffening of muscles after death due to biochemical changes (especially the depletion of ATP).
- The onset and duration of rigor mortis depend on enzyme activity which is temperature sensitive.
- In colder temperatures $$(36^\circ F)$$, enzyme activity slows down. This slows the onset of rigor mortis.
- However, once established, the cold temperature also helps in preserving the muscles and slows down the processes (including proteolysis) that lead to the resolution of rigor mortis.
- Thus, while the onset of rigor is delayed, the **duration** of rigor mortis is prolonged, meaning that at a given time (two days later) the rigor might still be present or even appear “increased” compared to what one would expect in warmer conditions.

**Step 3. Conclusion**

- **Lividity:** Decreased (due to increased blood viscosity and slower pooling in the cold).
- **Rigor Mortis:** Increased (or prolonged) due to the slowed enzyme activity leading to a delayed onset and extended duration.

The correct choice is:  
**lividity - decreases / rigor - increases**
Lividity decreases and rigor mortis increases.

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