Question

Contraction of a sarcomere, and thus contraction of the muscle as a whole, is accomplished by a cyclic sequence of interactions between actin (thin filaments) and myosin (thick filaments) in the sarcomere. Understanding this sequence of events is essential to understanding the mechanism of muscle contraction at the cellular and molecular levels. Begin by considering a relaxed muscle. In this state, the myosin molecules of the thick filaments are not in contact with the actin of the thin filaments, and ADP and Pi are bound to the myosin heads. An action potential on the muscle cell plasma membrane initiates contraction of the sarcomeres from this relaxed state. Drag the labels to their appropriate locations on the cycle diagram below.

Answer 1

The sliding filament model of muscle contraction explains how the thick and thin filaments slide past each other to shorten the sarcomere and cause muscle contraction.

Step-by-step explanation:

The sliding filament model of muscle contraction describes how the thick myosin filaments repeatedly attach to and pull on the thin actin filaments, causing the sarcomere to shorten and the muscle to contract. This process requires the energy provided by ATP. The sliding of the filaments is facilitated by the binding and release of the myosin heads from the actin filaments in a cyclic sequence, resulting in the sliding of the filaments past each other.