Forensic Science: Lividity Concepts

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Questions and Answers

What is lividity and what two things can it tell a forensic investigator about the death?

Lividity is the pooling of blood in the body. It tells investigators if the body was moved and how long the person has been dead.

When does lividity first begin and when is it fixed?

It begins two hours after death and it's fixed after eight hours.

What is livor mortis?

The color the body changes to when lividity sets in.

What is rigor mortis?

The stiffening of the skeletal muscles after death. Signup and view all the answers

Describe three things that affect rigor mortis and why.

<ol> <li>A person's weight - the more body fat, the slower rigor mortis is and vice versa. 2. Sun exposure - direct sunlight speeds up rigor mortis. 3. The type of clothing - the presence of clothes on the body speeds up rigor mortis.</li> </ol> Signup and view all the answers

Explain the difference between cause of death and mechanism of death. Give two examples.

Cause of death is the immediate reason for a person's death. Mechanism of death is the specific body failure that leads to death. Examples: Cause of death could be shooting, the mechanism would be loss of blood. Cause of death could be a heart attack, the mechanism would be the heart stopped beating. Signup and view all the answers

What are the four manners of death?

<ol> <li>Natural - caused by interruption and failure of body functions. 2. Accidental - when investigators can't tell if the death was deliberate or not. 3. Suicidal - when a person purposefully kills themselves. 4. Homicidal - when a person kills another person.</li> </ol> Signup and view all the answers

What is death?

The cessation, or end, of life. Signup and view all the answers

What is proximate cause of death?

The underlying cause of death. Signup and view all the answers

What is algor mortis and at what rate does it occur?

Algor mortis is the temperature/heat loss of a corpse. The body cools at a rate of $0.78$ degrees Celsius per hour. Signup and view all the answers

What is autolysis?

The spontaneous breakdown of cells as they self-digest. Signup and view all the answers

What is decomposition?

The process of rotting and breaking down. Signup and view all the answers

What can stomach contents tell you about the time of death?

Whether or not the death was recent or not. Signup and view all the answers

What is entomology?

The study of insects as they pertain to legal issues. Signup and view all the answers

Why are insects attracted to a decomposing body and which insects arrive first?

They're attracted to the smell of the body. Blowflies are the first insects to arrive. Signup and view all the answers

What are the stages of insect development?

<ol> <li>Egg 2. Larva 1 (Instar 1) 3. Larva 2 (Instar 2) 4. Larva 3 (Instar 3) 5. Pre-pupa 6. Early and late pupa 7. Adult.</li> </ol> Signup and view all the answers

What is larvae?

The immature form of an animal that undergoes metamorphosis. Signup and view all the answers

What are instars?

The three larval stages of insect development. Signup and view all the answers

What are pupae?

When the larva forms a capsule around itself and changes into adult form. Signup and view all the answers

Study Notes

Lividity and Livor Mortis

Lividity refers to blood pooling in the body and indicates if the body was moved and the time since death.
Lividity begins two hours post-mortem and becomes fixed after eight hours.
Livor mortis describes the color change of the body due to lividity.

Rigor Mortis

Rigor mortis is the stiffening of skeletal muscles after death.
Influencing factors for rigor mortis:
- Body weight: Higher fat content slows down rigor mortis.
- Sun exposure: Direct sunlight accelerates rigor mortis.
- Clothing: Presence of clothing speeds up rigor mortis.

Cause and Mechanism of Death

Cause of death is the immediate reason for death; mechanism of death is the specific physiological failure leading to death.
Examples:
- Shooting (cause) leads to blood loss (mechanism).
- Heart attack (cause) results in cessation of heartbeat (mechanism).

Manner of Death

Four manners of death:
- Natural: Resulting from bodily function failure.
- Accidental: Unclear if the death was intentional or not.
- Suicidal: Intentional self-killing.
- Homicidal: Intentional killing of another person.

Definitions of Death

Death is defined as the cessation or end of life.
Proximate cause of death refers to the underlying cause.

Post-Mortem Changes

Algor mortis describes the cooling of the body at a rate of approximately 0.78°C per hour.
Autolysis involves spontaneous cellular breakdown due to self-digestion.
Decomposition is the rotting and breakdown process following death.

Forensic Entomology

Stomach contents can indicate the recency of death.
Entomology is the study of insects in legal contexts, with blowflies being the first attracted to decomposing matter.

Insect Development Stages

Stages of insect development include:
- Egg
- Larva (three instar stages)
- Pre-pupa
- Pupae (development into adult form)
Larvae refer to the immature form of an insect, which undergoes metamorphosis.

Instars and Pupae

Instars are the three larval stages of development preceding adulthood.
Pupae are the encased stage where larvae transform into adult insects.

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Description

This quiz covers key concepts related to lividity and its implications for forensic investigators. It includes important definitions and timelines associated with livor mortis. Test your knowledge on how lividity can provide insights into post-mortem changes.