DNA forensics Flashcards
What are the Post-mortem Changes?
Pallor Mortis (Paleness)
Livor Mortis (Bluish color)
Algor Mortis (Coldness)
Rigor Mortis (Stiffness)
Eye changes.
Putrefaction
Mummification
Pallor mortis(30 min)
Pallor mortis results from the collapse of capillarycirculation throughout the body.
-The first stage of death, is an after-death paleness that occurs in those with light/white skin.
-Occurs almost immediately, generally within 15–25 minutes after death.
-No use in determining the time of death, aside from saying that it happened less than 30 minutes ago.
Livor mortis(fixed after 8 hours)
Hypostasis is the second stage of death.
-After Pallor Mortis, gravitythen causes the blood to sink down into the lower parts of the body except the independent part.
-starts in 20–30 minutes, but it is usually not observable by the human eye until 2 hours after death in independent parts of the dead body.
-It can be fixed in its place after 8 hours.
Medicolegal of hypostasis
1.Sure sign of death.
2.Rough estimation of time of death.
3.Detection if the position of the body has been changed after death or not.
4.Identification of possible cause of death through color and site.
Algor Mortis (after 18–24hours)
1- The third stage of death, is the post-mortem gradual decrease in body temperature, until it equalizes the temperature of the surrounding environment.
2- is the result of a cessation inthermoregulation. As body temperature is controlled by thehypothalamus
Factors affecting Algor Mortis (Body Cooling)
1-Body temperature.
2-Body weight: The rate of cooling will be slower in an obese body.
3-Temperature of the environmental surroundings: The rate of cooling will increase in a body immersed in water, a naked body, and a thin body( elder and babies).
4-Clothes worn by cadaver: If the body is wearing clothes
Rigor Mortis (Appears after 2 hours)
-is the fourth stage of death, resulting in the stiffening of the body muscles due to chemical changes in their myofibrils.
-helps in estimating the time since death as well to ascertain if the body had been moved after death.
- (disappears after 12-36 hours)
Primary flaccidity( lasts between 2-6 hours)
-General relaxation of the entire muscular system immediately after death, lasts between 2-6 hours.
-Starts before rigor mortis
-There is respond to electrical & mechanical stimuli
Secondary flaccidity (occurs 18-24 hours after death )
1- Complete relaxation of the body muscles, occurs 18-24 hours after death
2- Follows rigor mortis
3- No respond to electrical & mechanical stimuli.
What is Cadaveric spasm?
1- is a rare form of muscular stiffening that occurs at the moment of deathand persists into the period of rigor mortis.
2- stronger stiffening of the muscles than rigor mortis.
3- It is neurogenic in nature and means the death occurred in intense physical and/or emotional activity.
Eyes changes
1-The clear glistening appearance of the cornea is lost, the cornea appears dry, cloudy and opaque.
2-The light reflex is lost.
3-The intraocular tension falls and the eye balls become flaccid and sink into the orbit.
4-The blood stream in the retinal vessels becomes segmented.
5-Taches noire (3 hr after death)
Mummification
is a modification of the putrefaction process, characterized by the dehydration of the cadaveric tissues.
Asphyxia
can be defined as the condition of deficient supply of oxygento the body, which arises from abnormal breathing.
What are the main kinds of asphyxia?
1-Mechanical asphyxia
2-Traumatic asphyxia
3-Perinatal (birth) asphyxia
4-Compressive (compression) asphyxia
1-Mechanical asphyxia
when an object or a physical force stops you from breathing. It also includes body positions
2-Traumatic asphyxia
caused due to mechanical fixation of the chest so that normal movements of chest wall are prevented.
-occurs when a large weight falls onto or presses down on an individual’s chest.
3-Perinatal (birth) asphyxia.
Birth asphyxia is when your baby doesn’t get enough oxygen right before, during or right after birth.
4-Compressive (compression) asphyxia
is a type of mechanical asphyxiation. A strong external force presses on your chest or abdomen. Examples include a large crowd pushing against your body
– Mechanical asphyxia types:
Smothering, hanging, throttling, strangulation, chocking, drowning and traumatic asphyxia
Causes of asphyxia
- Mechanical asphyxia
- Poisoning
- Pathological:
Poisoning
- Morphine, barbiturate causing central asphyxia.
- Strychnine causing peripheral asphyxia.
- Carbon monoxide CO.
-Cyanide.
Autopsy findings in asphyxia:
A) Externally:
-The face is congested, swollen with petechiae.
-Eyes appear prominent, congested, dilated pupils, and subconjunctival petechiae.
-Lips finger nails are deeply cyanosed.
-Froth from mouth and nostrils (may be bloody)
-Tongue is protruded, sometimes bitten
- Semen may be ejaculated.
-Hypostasis is dark.
-Evidence of the cause: nail abrasion on face
Autopsy findings in asphyxia:
B) Internally:
Blood is dark and more fluid.
-Internal organs are deeply congested.
Evidence of the cause:
-Bruises in subcutaneous tissue of the face, Neck,
fracture of hyoid bone or laryngeal cartilage, foreign body in air passages.
1-Hanging
Constriction of neck anatomical structure by ligature using weight of the body
2- Strangulation
asphyxia by closure of the blood vessels and/or air passages in the neck due to external pressure by rope
Ligature strangulation:
is a violent form of death, which results from constricting the neck by means of a rope
Throttling
When constriction is produced by the pressure of the fingers and palms upon the throat.
Mugging
When strangulation is brought about by compressing the throat with a foot, knee, bend of elbow, or some other solid substances.
Smothering
Homicidal smothering is the deliberate occlusion of the external airways, usually using the hands, pillows, or bedding
Gagging
mechanical obstruction of oral cavity. It is usually resorted to prevent the victim from shouting for help.
-Later the gag becomes progressively soaked with saliva and/or mucous.
Choking
It is a form of asphyxia caused by an obstruction within the air passage by a foreign body
Drowning
defined as a process of respiratory impairment from submersion in a liquid medium.
Drowning is categorized into 4 principal types:
1- Wet Drowning
2- Dry drowning
3- Secondary drowning
4- Immersion syndrome
Cuticle
Its scales,
How many there are per centimeter,
How much they overlap,
Their overall shape, and
How much they protrude from the surface
Its thickness, and
Whether or not it contains pigment
The cortex varies in:
Thickness
Texture
Color
Medulla
The medulla may vary in:
Thickness
Continuity - one continuous structure or broken into pieces
Opacity - how much light is able to pass through it
The Life Cycle of Hair
1- anagen stage, hair actively grows.
2-In the catagen stage, the hair grows and changes.
3- telogen stage
Hair type
Scalp hair
Pubic hairs
Beard hairs
Eyebrow hairs
