please explain rigor mortis?

Answer 1

Rigor mortis refers to the state of a body after death, in which the muscles become stiff. It commences after around 3 hours, reaching maximum stiffness after 12 hours, and gradually dissipates until approximately 72 hours after death. Rigor mortis occurs due to changes in the physiology of muscles when aerobic respiration ceases.

Muscles are made up of two types of fibre. These fibres have connections between them that lock and unlock during muscle contraction and relaxation. These connections are controlled by a biochemical pathway within the cell, which is partially driven by the presence of calcium ions. The concentration of calcium ions is higher in the fluid surrounding muscle cells than it is inside the cells, so calcium tends to diffuse into the cell. High calcium levels inside the cell drive the biochemical pathway in the direction that maintains muscle contraction. To relax, muscle cells must expel the calcium ions from the cell and this requires energy molecules to pump them across the cell membrane.

After a body has died, the chemical reaction producing these energy molecules is unable to proceed because of a lack of oxygen. The cells no longer have the energy to pump calcium out of the cell and so the calcium concentration rises, forcing the muscles to remain in a contracted state. This state of muscle stiffening is known as rigor mortis and it remains until the muscle proteins start to decompose.

Answer 2

What Causes Rigor Mortis

Answer 3

Rigor mortis is a recognisable sign of death (Latin "mors, mortis") that is caused by a chemical change in the muscles, causing the limbs of the corpse to become stiff (Latin "rigor") and difficult to move or manipulate. Assuming mild temperatures, rigor usually sets in about 3-4 hours after clinical death, with full rigor being in effect at about 12 hours, and eventually subsiding to relaxation at about 36 hours. Times for the onset of rigor mortis can vary from a few minutes to several hours depending on the temperature of the environment in which the body is found.

Answer 4

Rigor mortis is a recognisable sign of death (Latin "mors, mortis") that is caused by a chemical change in the muscles, causing the limbs of the corpse to become stiff (Latin "rigor") and difficult to move or manipulate. Assuming mild temperatures, rigor usually sets in about 3-4 hours after clinical death, with full rigor being in effect at about 12 hours, and eventually subsiding to relaxation at about 36 hours. Times for the onset of rigor mortis can vary from a few minutes to several hours depending on the temperature of the environment in which the body is found.

Answer 5

A few hours after a person or animal dies, the joints of the body stiffen and become locked in place. This stiffening is called rigor mortis. Depending on temperature and other conditions, rigor mortis lasts approximately 72 hours. The phenomenon is caused by the skeletal muscles partially contracting. The muscles are unable to relax, so the joints become fixed in place. More specifically, what happens is that the membranes of muscle cells become more permeable to calcium ions. Living muscle cells expend energy to transport calcium ions to the outside of the cells. The calcium ions that flow into the muscle cells promote the cross-bridge attachment between actin and myosin, two types of fibers that work together in muscle contraction. The muscle fibers ratchet shorter and shorter until they are fully contracted or as long as the neurotransmitter acetylcholine and the energy molecule adenosine triphosphate (ATP) are present. However, muscles need ATP in order to release from a contracted state (it is used to pump the calcium out of the cells so the fibers can unlatch from each other). ATP reserves are quickly exhausted from the muscle contraction and other cellular processes. This means that the actin and myosin fibers will remain linked until the muscles themselves start to decompose. Rigor mortis can be used to help estimate time of death. The onset of rigor mortis may range from 10 minutes to several hours, depending on factors including temperature (rapid cooling of a body can inhibit rigor mortis, but it occurs upon thawing). Maximum stiffness is reached around 12-24 hours post mortem. Facial muscles are affected first, with the rigor then spreading to other parts of the body. The joints are stiff for 1-3 days, but after this time general tissue decay and leaking of lysosomal intracellular digestive enzymes will cause the muscles to relax. It is interesting to note that meat is generally considered to be more tender if it is eaten after rigor mortis has passed. :) :)

Answer 6

G'day Louise C,

Thank you for your question,

Rigor mortis is a recognisable sign of death (Latin "mors, mortis") that is caused by a chemical change in the muscles, causing the limbs of the corpse to become stiff (Latin "rigor") and difficult to move or manipulate. Assuming mild temperatures, rigor usually sets in about 3-4 hours after clinical death, with full rigor being in effect at about 12 hours, and eventually subsiding to relaxation at about 36 hours. Times for the onset of rigor mortis can vary from a few minutes to several hours depending on the temperature of the environment in which the body is found.

The biochemical cause of rigor mortis is hydrolysis of ATP in the muscle tissue, the chemical energy source required for movement. Myosin molecules devoid of ATP become permanently adherent to actin filaments to form actomyosin complex, causing muscles to become rigid. After the pH of the muscle has become 5.5, release of autolytic enzymes stored in lysosomes will take place. The major proteolytic enzymes are Cathepsins and Calpains. These enzymes act at the myofibrillar proteins and hydrolyse them. As a result, the actomyosin complex is broken down and muscles become "soft" again. This is known as resolution of rigor.

I have attached sources for your reference.

Regards

Answer 7

Muscles always contracts and losens up using actin, myosin etc. After contraction, the muscle requires ATP for actin to let go of the myosin, or to relax. When you die, you no longer produce ATP (energy), so muscle stays contracted. Or rigor mortis...stiff...

Hope that helped a little... I can explain in more details but a google search will do the same for you.

Answer 8

Ok...but only if you explain Goth and Emo first.

I just don't get it.

Answer 9

http://en.wikipedia.org/wiki/Rigor_mortis

Answer 10

http://www.youtube.com/watch?v=kuLjuD3XrXI

http://www.youtube.com/watch?v=H2jtRWFOd04

http://www.youtube.com/watch?v=A55CzcYl7qQ