Why are skeletal and cardiac muscles striated?

• A. Because they contain sarcomeres with alternating bands of actin and myosin filaments.
• B. Because they have a high density of mitochondria for energy production.
• C. Because they are composed of smooth muscle fibers.
• D. Because they are controlled by the autonomic nervous system.

Answer: (A)

Verified step by step guidance

1. Understand the structure of muscle fibers: Skeletal and cardiac muscles are composed of muscle fibers that have a distinct banding pattern known as striations.
2. Learn about sarcomeres: Sarcomeres are the basic functional units of muscle fibers, responsible for muscle contraction. They are organized in a repeating pattern within the muscle fibers.
3. Identify the components of sarcomeres: Sarcomeres contain alternating bands of actin (thin filaments) and myosin (thick filaments), which create the striated appearance.
4. Explore the role of actin and myosin: During muscle contraction, actin and myosin filaments slide past each other, which is facilitated by the striated arrangement within the sarcomeres.
5. Differentiate between muscle types: Recognize that smooth muscle fibers do not have sarcomeres and therefore lack striations, unlike skeletal and cardiac muscles.