Rigor mortis refers to which of the following processes?

Rigor mortis refers to which of the following processes?

• A. Process when the muscles of the body stiffen related to a chemical change occurring within the muscles after death
• B. Decomposition of tissues due to bacteria
• C. Cessation of heart activity
• D. Increase in body temperature after death

Answer: (A)

Rigor mortis is the stiffening of the body's muscles after death caused by chemical changes in the muscle tissue when ATP production stops. In living muscle, ATP is needed to detach myosin heads from actin after a contraction. After death, no new ATP is made, calcium leaks into the muscle cells, and the cross-bridges between actin and myosin become locked in place. That locking produces stiffness that starts in smaller muscles and moves to larger ones, lasting for a period before decomposition breaks the tissues down and relief of stiffness occurs. This is not the same as decomposition caused by bacteria, nor is it the cessation of heart activity itself, and it’s not an increase in body temperature (the body typically cools after death).

Rigor mortis is the stiffening of the body's muscles after death caused by chemical changes in the muscle tissue when ATP production stops. In living muscle, ATP is needed to detach myosin heads from actin after a contraction. After death, no new ATP is made, calcium leaks into the muscle cells, and the cross-bridges between actin and myosin become locked in place. That locking produces stiffness that starts in smaller muscles and moves to larger ones, lasting for a period before decomposition breaks the tissues down and relief of stiffness occurs. This is not the same as decomposition caused by bacteria, nor is it the cessation of heart activity itself, and it’s not an increase in body temperature (the body typically cools after death).