What is the cause of rigamortas (stiffining of bodies) in dead bodies?

Answer 1

Muscle fibers have long proteins called actin that are disposed as "railways" and form a long chain al along the muscle.
A second protein, miosin, has a movable head that "crawls" up the actin, dragging a limited amount of muscle mass with it. The coordinated movement of millions of these proteins produces the contraction of the muscle.
For this, muscles need two things: Calcium that allows the miosin head to "glue" to the actin, and ATP (an energy carrier molecule that is produced by the cellular respiration) that gives it the energy to move one step and be dettached for a new cycle.
When people die, there's no more respiration, so cells consume the lasts molecules remaining of ATP. So there's calcium, the miosin attaches firmly to the actin, but there's no aTP, so it doesn't move and it doesn't detach. That's Rigor Mortis. Eventually, when the cells die, the balance of ions change and the proteins start to break down and the corpse becomes very jellylike.

Answer 2

The correct term is rigor mortis. It is caused by inseparable binding of actin to myosin in the muscle fibers, which is essentially caused by a disappearing ATP supply. Actin and myosin normally need ATP to separate, so in the absence of ATP, this cannot happen. However, necrosis leads to the opening of lysosomes, which makes the cell acidic, cleaving actin and myosin.

The timeframe of rigor mortis is usually short after death for about a day or two, then the lysosomes release the acid.

Answer 3

Actually, the stiffening of dead bodies is called rigor mortis. It is caused by the partial contraction of skeletal muscles which results to unrelaxed muscles and the joints become fixed also and stiffens.

Answer 4

The tendons quit receiving blood and are no longer supple. Thus the joints stiffen.