FMGE 2008 - Forensic Medicine FMGE Practice Questions and MCQs
Question 1: The poison that can be detected in hair/bones long after death is:
- A. Lead
- B. Arsenic (Correct Answer)
- C. Mercury
- D. Cannabis
Explanation: ***Arsenic***
- **Arsenic** has a high affinity for **keratin-rich tissues** like hair and nails, where it accumulates and can be detected long after exposure or death.
- It also deposits in **bones**, allowing for its detection in archaeological remains, making it a classic poison for historical forensic analysis.
*Lead*
- While **lead** also accumulates in bones and teeth, its primary long-term storage is in these tissues, not predominantly in hair in a way that is easily detectable post-mortem in the same manner as arsenic.
- Lead poisoning detection in **hair** is possible but less reliable or common for long-term retrospective analysis compared to arsenic due to varying growth rates and external contamination.
*Mercury*
- **Mercury**, particularly organic forms, can accumulate in hair, but its detection for very long periods post-mortem tends to be more variable and less definitive for pinpointing chronic poisoning than arsenic in hair and bone.
- Its excretion and distribution patterns differ, making it somewhat less persistent in hair/bone over extremely long periods compared to arsenic, which binds strongly to **sulfhydryl groups**.
*Cannabis*
- **Cannabis** metabolites can be detected in hair for an extended period (months), but typically not "long after death" in the same forensic toxicology context as heavy metals which are incorporated into bone and keratin structures.
- As an organic compound, its stability and detectability diminish over time in a way that heavy metals like arsenic, which become part of the mineral matrix, do not.
Question 2: True about rigor mortis are all, except:
- A. It disappears in the sequence as it appears
- B. It lasts 18-36 h in summer
- C. Seen immediately after death (Correct Answer)
- D. It lasts 24-48 h in winter
Explanation: ***Seen immediately after death***
- **Rigor mortis** does not appear immediately after death; it typically begins 2-4 hours post-mortem.
- The onset and progression of rigor mortis are dependent on the depletion of **ATP** and accumulation of lactic acid, which takes time.
*It disappears in the sequence as it appears*
- The resolution of rigor mortis, often referred to as **secondary flaccidity**, generally follows the same order of onset.
- This sequential relaxation is due to the breakdown of muscle proteins by **autolytic enzymes**.
*It lasts 18-36 h in summer*
- In warmer conditions, such as summer, the metabolic processes and decomposition accelerate, causing rigor mortis to develop faster and resolve sooner.
- The duration of rigor mortis in summer can indeed be shorter, typically ranging from **18 to 36 hours**.
*It lasts 24-48 h in winter*
- In colder environments, like winter, the onset and duration of rigor mortis are prolonged due to slower biochemical reactions.
- The duration of rigor mortis can extend to **24-48 hours or even longer** under these conditions.
Question 3: Vitreous humor is preserved in suspected poisoning with:
- A. Cyanide
- B. Morphine
- C. Alcohol (Correct Answer)
- D. Carbon monoxide
Explanation: ***Alcohol***
- **Vitreous humor** is an ideal sample for postmortem alcohol analysis due to its **sequestration** from other body fluids, which minimizes postmortem production or degradation of alcohol.
- Its **avascular nature** and **slow diffusion** rates ensure that the alcohol concentration in the vitreous humor closely reflects the ante-mortem blood alcohol concentration.
*Cyanide*
- Sampling **vitreous humor** is generally not the primary choice for detecting cyanide because cyanide is rapidly absorbed and metabolized, making its detection more reliable in other tissues.
- Cyanide can degrade in biological samples, and its concentration in the vitreous humor may not accurately reflect the lethal dose or recent exposure.
*Morphine*
- While **vitreous humor** can be used for opiate detection, **blood and urine** are generally preferred for initial screening and quantitative analysis of morphine.
- Morphine undergoes metabolism during its elimination, and its distribution into the vitreous humor might not always accurately reflect the **pharmacodynamics** or precise time of exposure compared to blood.
*Carbon monoxide*
- **Carbon monoxide (CO) poisoning** is primarily diagnosed by measuring **carboxyhemoglobin levels** in blood, as CO binds avidly to hemoglobin.
- The vitreous humor is not a suitable sample for detecting carbon monoxide or carboxyhemoglobin as it lacks red blood cells and hemoglobin, which are the targets of CO toxicity.