What Causes Rigor Mortis?

Q. What is Rigor Mortis?

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Q. What causes Rigor Mortis?

Ans. Chemical changes in the muscles after death result in rigor mortis. 

Muscle transverse tubules, a part of the sarcoplasmic reticulum, release calcium ions when action potentials delivered by the nerves reach their target muscles. The concentration of calcium ions within a muscle fibre is controlled by the sarcoplasmic reticulum that envelops each myofibril. The sarcoplasmic reticulum “sequesters” calcium ions away from the cytosol in a resting muscle fibre by binding them to a protein called calsequestrin. Fast-contracting muscle fibres contain more calsequestrin than slow-contracting fibres do.

Transverse tubules that move from the surface of each muscle fibre carry impulses that are sent by the nervous system to tell the fibres to contract whenever the tubules approach the sarcoplasmic reticulum. Any sarcoplasmic reticulum region near the transverse tubule will release calcium ions in the presence of such a signal. The movement of troponin and tropomyosin along the muscle filament as a result of the released calcium ions results in the beginning of muscular contraction. After the muscle has contracted and there are no more impulses from the neurological system, the remaining signalling neurotransmitter, acetylcholine, is broken down by acetylcholinesterase.

Rigor Morits

The sarcoplasmic reticulum’s SERCA pump (sarcoplasmic endoplasmic reticular calcium ATPase pump) stops releasing calcium ions and locks them up in quarantine zones. Myosin is prevented from moving since there aren’t enough calcium ions present, which allows the muscle to relax. The only thing that can keep a muscle flexed for any amount of time in a living body is continual nervous system messages. Because of brain death, there are no nervous system messages in the dead, and muscle contraction then only arises from chemical imbalance. A SERCA pump needs lots of ATP, as its full name implies. All metabolic processes stop working after death, and ATP is no longer created. As a result, the sarcomere has chronically high calcium ion levels and no sequestering mechanism. Therefore, they cannot be eliminated by the SERCA pump. This causes rigor mortis, or prolonged contraction.

Q. What is Cadaveric Spasm? Are Rigor Moris and Cadaveric Spasm Same?

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MCQ: What causes rigour mortis, or the hardening of the body after death?

A. Sarcoplam’s accunulation of molecules of stiff proteins.
B. The absence of ATP, which is required to dissociate the actin-myosin bond.
C. A drop in body temperature upon death.
D. Tissue death owing to a lack of oxygen

Ans. B. The absence of ATP, which is required to dissociate the actin-myosin bond.