decomposition- lqc 1b

Question 1

describe what happens immediately after death

Answer 1

autolysis occurs- digestive enzymes from the digestive tract and lysosomes start to break down cells

Question 2

describe the role of bacteria in the first stages of decomposition

Answer 2

bacteria from the digestive tract and gas exchange system rapidly invade the tissue. they release digestive enzymes. this is putrefaction. the lack of oxygen promotes the growth of anaerobic bacteria

Question 3

describe the first signs of decomposition

Answer 3

a greenish discolouration appears on the skin of the abdomen- due to anaerobic bacteria converting haemoglobin into sulfhaemoglobin, the discolouration spreads across the body darkening to reddish-green and then purple-black

Question 4

what is the time frame for the discolouration

Answer 4

starts between 36-72 hours

Question 5

describe what happens during and after the gas phase

Answer 5

bacteria produce gases (hydrogen sulfide, methane, CO2, ammonia, hydrogen) in the tissues and intestine. the body becomes bloated and starts to smell. after further decomposition, the gas escapes, the body deflated and fluid drains away. the tissues shrink and the body starts to dry

Question 6

what is the time frame of the gas production

Answer 6

usually after 7 days. if temp remains high (>26°c) it can appear within 72hrs

Question 7

describe the factors that can affect the rate of decomposition

Answer 7

ambient temperature- low temps slow, warm temps speed up
clothing- insulation
body injuries- aid entry of bacteria
intense heat- slows as enzymes denature

Question 8

why is the process of decomposition so useful in determining time of death

Answer 8

it follows a specific sequence