Contractile unit of muscle fibres :-a)H lineb)Sarcomerec)H zoned)NoneCorrect answer is option 'B'. Can you explain this answer?

Question

Answer

A sarcomere is the basic contractile unit of muscle fiber.

Each sarcomere is composed of two main protein filaments, actin and myosin, which are the active structures responsible for muscular contraction.

Answer

The entire cross section of the muscle fibre is taken up by long, cylindrical strands of contractile proteins called myofibrils. One myofibril is divided into segments called sarcomeres. These are the contractile units of a muscle. A dark stripe called a Z disc marks the ends of one sarcomere and the beginning of the next.

Answer

B

Answer

The Sarcomere: The Basic Contractile Unit of Muscle. A sarcomere is the basiccontractile unit of muscle fiber. Each sarcomere is composed of two main protein filaments—actin and myosin—which are the active structures responsible formuscular contraction.

Answer

Understanding the Sarcomere
The sarcomere is the fundamental contractile unit of muscle fibers, specifically within striated muscle such as skeletal and cardiac muscles. It plays a crucial role in muscle contraction and movement.
Structure of Sarcomere
- The sarcomere is defined by the region between two Z lines (Z discs).
- Each sarcomere contains thick and thin filaments:
- Thick filaments: Composed mainly of myosin.
- Thin filaments: Primarily made up of actin, along with tropomyosin and troponin.
Function of Sarcomere
- The sarcomere contracts when the thick and thin filaments slide past each other, a process regulated by calcium ions and ATP.
- This sliding mechanism is known as the sliding filament theory. During contraction:
- The H zone (the area where only thick filaments are present) and the I band (the area with only thin filaments) narrow.
- The A band (where thick and thin filaments overlap) remains constant in length.
Relevance in Muscle Physiology
- Each muscle fiber is made up of numerous sarcomeres arranged end to end, allowing for coordinated contractions across the entire muscle.
- Understanding the sarcomere is essential for comprehending muscle mechanics, physiology, and the effects of various diseases on muscle function.
In summary, the sarcomere is the basic structural and functional unit of muscle tissue, critical for muscle contraction and overall movement.

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