Striated muscles contract becauses of

Options

A. sliding of myosin filaments on actin filaments
B. sliding of actin filaments on myosin filaments
C. myosin filaments coming close to each other
D. actin filaments sliding over one another

Answer

**Step-by-Step Solution:**

1. **Definition of Striated Muscles**: Striated muscles, also known as skeletal muscles, are characterized by their cross-striations and are under voluntary control. They are responsible for movements in the body.

2. **Structure of Striated Muscles**: These muscles are made up of long, cylindrical fibers that contain myofibrils. Myofibrils are further divided into units called sarcomeres, which are the basic functional units of muscle contraction.

3. **Mechanism of Contraction**: The contraction of striated muscles occurs through a process known as the sliding filament theory. This theory explains how muscle fibers contract by the sliding of two types of filaments: actin (thin filaments) and myosin (thick filaments).

4. **Sliding of Filaments**: During contraction, the myosin heads attach to binding sites on the actin filaments. The myosin heads then pull the actin filaments towards the center of the sarcomere, causing the sarcomere to shorten. This sliding action is what leads to the overall contraction of the muscle.

5. **Conclusion**: Therefore, striated muscles contract because of the sliding of myosin filaments over actin filaments, which brings the filaments closer together and shortens the muscle.

**Final Answer**: Striated muscles contract because of the sliding of myosin filaments on actin filaments.

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