Postmortem Changes and Time of Death

Vocabulary flashcards covering postmortem changes, early and late stages of death, biochemical markers, temperature estimation models, and forensic decomposition phenomena.

Uniform Determination of Death Act (UDDA)

A legal standard adopted by the American Bar Association and American Medical Association defining death as either (1) irreversible cessation of circulatory and respiratory functions, or (2) irreversible cessation of all functions of the entire brain, including the brain stem.

Postmortem Interval (PMI)

The total time elapsed between the occurrence of death and the attempt to estimate or determine the time since death.

Pallor Mortis

The postmortem paleness of the skin occurring within $15$ to $30\,\text{minutes}$ after death due to the cessation of blood circulation.

Algor Mortis

The postmortem cooling of the body from normal body temperature (37\,\text{^\circ C}) at an estimated average rate of 1.5\,\text{^\circ F/hour} due to the loss of metabolic heat production.

Rigor Mortis

The postmortem stiffening of body muscles caused by the progressive depletion of adenosine triphosphate (ATP).

Nysten's Law

The rule describing the sequence of rigor mortis, affecting first the muscles of mastication, followed by the face and neck, upper trunk and arms, and lastly the legs and feet.

Livor Mortis

The purplish-blue skin discoloration that appears within $30\,\text{minutes}$ to $2\,\text{hours}$ postmortem due to the gravitational pooling of blood in dependent cutaneous vessels.

Somatic Death

The immediate stage of death (also known as systemic death) marked by the irreversible cessation of vital functions in the brain, heart, and respiratory system.

Molecular Death

The early postmortem period (also known as cellular death) during which individual cells and tissues gradually lose viability and undergo biochemical and physical changes.

Tache noire de la sclérotique

A dark, reddish-brown triangular or band-like ocular drying artifact that develops across the exposed sclera when the eyelids remain open after death.

Kevorkian Sign

The postmortem fragmentation or 'trucking' of blood vessels visible in the retina, appearing within minutes after death and lasting for about $1\,\text{hour}$.

Thanatometer

A $25\,\text{cm}$ long thermometer with a temperature range of 0\,\text{^\circ C} to 50\,\text{^\circ C} used to measure body core temperature postmortem.

Vitreous Potassium Level

The concentration of potassium in the eye's vitreous humor that predictably rises non-linearly postmortem, aiding in postmortem interval estimation when corrected for decedent age and ambient temperature.

Autolysis

The aseptic self-digestion and breakdown of body cells and tissues mediated by internal cellular enzymes without bacterial action.

Maceration

The aseptic autolytic decomposition of a fetus within the amniotic cavity, characterized by skin slippage and brownish-black discoloration of underlying tissues.

Putrefaction

The decomposition of body proteins and tissues carried out by microbial action, beginning within an hour of death and reaching peak activity around $24\,\text{hours}$.

Marbling

A dark, branching, vein-like discoloration on the skin caused by erythrocyte hemolysis and sulphahemoglobin formation within superficial blood vessels during putrefaction.

Postmortem Purging

The expulsion of dark putrefactive liquids and gases from the mouth and nostrils driven by increased intra-abdominal gas pressure during decomposition.

Casper's Dictum

A forensic rule stating that a body decomposes in air twice as rapidly as when submerged in water, and eight times as rapidly as when buried in earth.

Adipocere

A yellowish, greasy, waxy substance formed during decomposition in warm, moist, anaerobic environments through the saponification (hydrolysis and hydrogenation) of body fatty tissues into palmitic, oleic, and stearic acids.

Mummification

A modification of putrefaction occurring in dry, warm, and airy environments, characterized by tissue desiccation causing the skin to become brown, hard, stretched, and leathery.

Blowfly Life Cycle

The predictable developmental progression of blowflies on a body—ranging from egg laying on day 1, larva hatching on day 2, prepupation at days 8-9, to adult fly emergence at two weeks—used in forensic entomology to calculate PMI.