Question

Corpses usually exhibit rigor mortis because_________

a. ATP hydrolysis is stimulating myosin head attachment to actin
b. a lack of ATP hydrolysis prevents myosin head detachment from actin
c. calcium stores become deficient
d. sodium stores become deficient

Answer 1

Rigor mortis occurs because a lack of ATP hydrolysis after death prevents myosin head detachment from actin, leading to muscle stiffness.

Step-by-step explanation:

Corpses usually exhibit rigor mortis because a lack of ATP hydrolysis prevents myosin head detachment from actin. When a person is alive, ATP is constantly produced and used by muscle cells for various functions, including muscle contraction where myosin heads bind to and pull on actin filaments. Following death, ATP production stops, and any remaining ATP is quickly depleted. Without ATP, myosin heads cannot detach from actin, thus causing the muscles to become rigid, a state known as rigor mortis. This muscular stiffness is the result of myosin and actin remaining bound together in the contracted state because there is no ATP available to release the myosin heads from the actin binding sites.

ATP hydrolysis is a process that provides the necessary energy for muscle contraction during life and for myosin heads to detach from actin following contraction. Once ATP is no longer available after death, muscle stiffness ensues because myosin heads remain attached to actin, creating the immobilized state observed in rigor mortis.