1.2 Post-mortem change Flashcards
What 3 changes can be identified in a cadaver?
- lesions
- agonal change
- post mortem change
lesions:
changes that are due to disease
agonal change:
changes that may occur prior to health
post mortem change:
changes occurring after death and before the cadaver is examined
What are major post mortem changes due to?
Autolysis and putrefaction
Autolysis:
action of the intrinsic enzyme system of the dead animal’s cells that results in self digestion
Putrefaction:
degradation of tissue by invasion and post-mortem activity of certain micro-organisms
during a post-mortem examination an enlarged spleen can indicate?
overdose
Rigor Mortis
The contraction of muscles occurring after death
- starts in the heart (blood pushed out of left ventricle)
- contraction reverses as carcase antolyses
How soon does rigor mortis commence and last?
Commences: 1-6 hours after death
Lasts: 1-2 days
When rigor Mortis sets in what is affected first?
Head and neck are affected first then extremities
What can accelerate rigor?
High environmental temperature or activity before death
What animals often have stronger rigor?
Muscular animals like grey hounds and race horses, emaciated animals have weaker rigor
Normal muscle contraction:
- Calcium is sequestered in the sarcoplasmic reticulum
- An action potential results in calcium being released into the cytoplasm, binding to
troponin on the actin myofibril, which exposes the binding site for myosin and results in
contraction of the sarcomere - ATP is required to sequester calcium back in the sarcoplasmic reticulum, resulting in
relaxation
Mechanism of rigor Mortis:
• Reduced ATP availability after death leads to a build up of calcium in the cytoplasm and consequent muscle contraction that persists as myosin binds to actin
• Subsequent muscle relaxation is due to enzymatic digestion of actin-myosin cross-links
How does blood separate post-morten?
- upper plasma lager: transtuant, looks like chicken fat
- lower red blood all layer: intense red, resembles jelly
Hypostatic congestion: Livor mortis
- Blood seeps to the dependent portions of
the body post-mortem - The process starts in an hour of death and stabilises in 12 to 24 hours
- May be apparent externally in animals with little hair cover (pigs)
- Best appreciated in the dependent lung and kidney during dissection
If an animal dies while lying on it’s right side what side will the blood he pulled to?
Right side - best appreciated in the dependent lung and kidney during dissection
Where is post mortemimbibition of blood best appreciated?
best appreciated on surface vessels of organs such as the intestine
Post Morten imbibition of bile pigments:
- Starts within hours of death
- Bile in the gall bladder penetrates the wall and stains adjacent tissue yellowish and then greenish brown
- Staining involves the local liver, omentum and gastrointestinal tract
Gaseous distension of the alimentary tract:
- bacterial fermentation producing gas in the alimentary tract continues after death
- may be surface pallor of adjacent organs due to the pressure of this distension squeezing blood out of this adjacent tissue
- abdominal viscera may be pale in comparison to thoracic viscera
** gas rises: distended loops may be pale and lower loops hypostatically congested (not to be confused with inflammation)
Antolysis characteristics:
particularly marked in the gut and associated glands such as the
pancreas that are enzyme-rich
• grossly tissue is uniformly paler and softer than normal
• the cut surface may exude fluid or be greasy
• cut surface tends to be greasy
Putrefaction
-Most putrefactive bacteria are anaerobes and include Clostridium spp. that are numerous in the large intestine
-proteins, fats and carbohydrates in the body substances are attacked by enzymes produced by these putrefactive bacteria, and are broken down peptides, amino acids and other compounds, including:
