Question

What happens inside muscles when they contract?

A. Myosin heads attach to and move along actin-binding sites.
B. Calcium produces contractions.
C. Actin produces myosin and ATP.
D. Calcium combines with ATP to produce sarcomeres.

Answer 1

Muscle contraction occurs when myosin heads attach to actin-binding sites and pull the actin filaments, resulting in muscle contraction. Calcium ions are involved in exposing the actin-binding sites, and ATP is required for the contraction to continue.

Step-by-step explanation:

Muscle contraction involves a process known as the sliding filament model. When a muscle contracts, myosin heads attach to actin-binding sites on actin filaments. This attachment forms a cross-bridge between the myosin and actin. During the power stroke, the myosin head pivots and pulls the actin filaments, resulting in muscle contraction. ATP is needed to continue the contraction, and calcium ions play a role in exposing the actin-binding sites.