Question

Rigor mortis is due to
A. Leakage of calcium out of the sarcoplasmic reticulum after death
B. Lack of ATP
C. Death of the motor neuron
D. Loss of electrical potential difference across the sarcolemma.

Answer 1

Hint:- The body needs the energy to maintain proper functioning, so ATP (Adenosine Triphosphate) serves as the energy currency for the body. ATP is one of the critical factors for muscle contraction.

Complete Answer:-
Rigor mortis or post-mortem rigidity is the stiffness of the muscles and joints of the body (making it difficult to move) or post-death of the person, which usually lasts between one and four days. It is the third stage and a recognizable sign of death occurring due to the chemical changes in the muscles or myofibrils and causing stiffening of the muscles of limbs.
After death chemical changes start in the muscles resulting in rigor mortis. When a person dies the body no longer receives oxygen because of this chemical reactions and exchanges do not take place, and muscles do not produce ATP. As muscles cells can generate ATP with oxygen known as aerobic respiration. ATP binds with the myosin and causes it to change the position and attach to the action and pull causing muscles to contract and it allows the muscle to move. ATP breaks the actin-myosin cross-bridge and freeing the myosin for the next contraction.
There four different stages of Rigor mortis i.e. Autolysis, Bloat, Active decay, and Skeletonization.
1. Autolysis- This stage begins immediately after death and it is also known as self-digestion. As blood circulation and respiratory activities stop after death. The body cannot receive oxygen or excretes out metabolic waste which leads to an acidic environment in the body which causes cell rupturing.
2. Bloat- Skin color starts fading due to the sulfur-containing compounds which are released by the bacteria, and foul odor secretes by the microorganisms in the process term as putrefaction.
3. Active decay- At this stage, all body parts become liquified. Soft tissues of the body decompose while hairs, cartilage, and bones of the decay remain.
4. Skeletonization- There is no fixed time frame when skeletonization occurs because the decomposition rate depends upon the loss of organic and inorganic components.

So, as we have discussed the correct answer is option B (Lack of ATP).

Note:- Rigor mortis starts after three to four hours of the death and reaches the maximum stiffness in twelve hours. Rigor mortis is a major application in the field of forensic science because it can be used to determine the exact time of death.