embalming 1- postmortem changes

Postmortem

period that begins after somatic death

• Physical PM changes do not change the chemical composition of the body or create new chemical

substances

• Chemical PM changes result in the formation of new chemical substances

Algor Mortis

postmortem cooling of the body to ambient temperature

Rate at which the body cools depends on various intrinsic and extrinsic factors

Intrinsic factors

from within the body

• Body weight

• Larger surface area = faster cooling

• More mass = slower cooling

• Temperature of body at time of death

• Higher temperature at time of death = longer time to cool off

Extrinsic Factors

from outside the body

• Clothing covering the body

• Temperature and humidity of environment

• Cause and manner of death

Hypostasis

settling of blood into dependent tissues

• Contact pallor – areas where blood flow has been inhibited

• Discolorations do not occur in areas of contact pallor

• Thinner blood will cause more hypostatic changes

Livor mortis (cadaveric lividity) – intravascular red-blue discoloration resulting from postmortem hypostasis of blood

Contact Pallor

areas where blood flow has been inhibited

• Discolorations do not occur in areas of contact pallor

• Thinner blood will cause more hypostatic changes

Livor mortis (cadaveric lividity)

intravascular red-blue discoloration resulting from postmortem hypostasis of blood

Dehydration

loss of moisture from body tissue, which may occur antemortem or postmortem ; the removal of water from a substance

Desiccation

extreme dehydration often resulting in post-embalming discolorations

Surface Evaporation

Surface evaporation – due to the passage of air over the body, moisture will evaporate from the surface of the body directly

Imbibition

ability of cells to draw moisture from the area surrounding them

Gravitation of body fluids

fluids will move toward dependent areas

Viscosity

the thickness of a liquid

• Occurs because of dehydration

• Formed elements of blood agglutinate:

Agglutination

increased viscosity of blood brought about by the clumping of particulate formed

elements in the blood vessels

Imbibition

other cells draw moisture out of the vascular system

Translocation of Microbes

Organisms may be motile, may enter and move through the bloodstream, or may move with shifts in moisture and hypostatic changes

pH shift

After death the pH shifts from slightly basic → acidic → basic

→ acidic

• After death, carbs being stored in the muscle tissue are broken down into pyruvic acid and lactic acid

• The presence of these acids causes the tissues to be acidic

• This usually occurs within the first three hours following death

• The body remains acidic during the rigor mortis stage

Neutral Period

Buildup of acid creates an ideal environment for soft proteins to decompose

• Proteins break down into nitrogenous products (ammonia, amines, etc.)

• These products, particularly ammonia, are basic

→ alkaline

• Nitrogenous products build up and neutralize the acids that have built up in the tissues

• Eventually as the nitrogenous products build up and acids are neutralized, the pH shifts to alkaline

• pH continues to become more alkaline as decomposition continues

Rigor Mortis

postmortem stiffening of the body muscles by natural body processes

• Affects only muscles and usually affects all muscles

• Stiffness of muscles because of rigor will get in the way of distribution of fluid

Timing of Rigor Mortis

Rigor marks the end of muscle cell life

• Rigor passes naturally within 36 – 72 hours

• Usually appears 2 – 4 hours after death

Cadaveric spasm (instantaneous rigor)

immediate stiffening of the muscles of a dead human body

Primary vs Secondary flaccidity

Primary flaccidity occurs before rigor begins

• Secondary flaccidity occurs after rigor mortis has passed naturally

How Rigor Mortis Affects Embalming

Rigor begins in the entire body at the same time however is most evident, at first, in small muscles

• Begins usually in the involuntary muscles of the eye

• Moves to the jaw, face, and neck

• Then makes its way to the upper extremities, trunk, and lower extremities

Rigor Mortis Severity Depends on

Temperature

• Ideal temperature is 98° F

• Rigor will not occur at temperatures below 32° F or above 120° F

• Age

• Gender

• Cause of death

• Condition of muscles

Postmortem stain

extravascular discoloration that occurs when heme seeps through the vessel walls and into

the body tissues

• Occurs because of hemolysis of blood (rupture of RBCs)

• Occurs about 6 – 10 hours after death

Postmortem caloricity

rise in body temperature after death due to continued cellular metabolism