Question

In striated muscle, rigor results from a low ATP concentration in the sarcomeres. As a result, the myosin heads remain attached to the actin filaments. What is the cause of rigor in striated muscle?

1) High ATP concentration in the sarcomeres
2) Low ATP concentration in the sarcomeres
3) High ADP concentration in the sarcomeres
4) Low ADP concentration in the sarcomeres

Answer 1

Rigor mortis in striated muscles is caused by a low concentration of ATP, which prevents the detachment of myosin heads from actin filaments, resulting in muscle rigidity.

Step-by-step explanation:

In striated muscle, rigor mortis occurs due to a low ATP concentration in the sarcomeres. During muscle contraction, myosin heads bind to actin filaments to form cross-bridges, which require ATP to detach after a power stroke. When ATP levels are insufficient, these myosin heads remain attached to actin, preventing relaxation and causing muscles to become rigid. Therefore, the correct answer to the question is: 2) Low ATP concentration in the sarcomeres.