Question

How is the structure of sarcomere suitable for the contractility of muscle? Explain its function according to the sliding filament theory.

Answer 1

Hint: Sarcomere is a fundamental unit of muscle which is responsible for muscle contraction. It is the repeating unit specifically between two Z lines. They are not present in all muscles, sliding filament theory was based on muscle contraction which was introduced in 1954 by researchers namely Andrew F. Huxley and Rolf Niedergerke.

Complete answer:
- Sarcomere has three parts where the I band consists of the thin filament, A band consists of an area of overlapping between the I and Z line.
- Z line consists of attachment from the neighbouring sarcomeres, thick filaments reside under the middle part of the sarcomere.
- Actin filament extends from Z line to H zone.
- Myosin filaments extend from one end of the A band through the H zone to other filaments A band.
- Myosin filaments remain in exceedingly constant periods all through muscle stretch or contraction.
- If myosin filaments agreement passed the duration of the A band, their ends fold up to form contraction bands.
- Myosin and actin filaments lie side-by way of-aspect within the A band and in the absence of ATP they do not shape pass-linkages.
- In the course of contraction, actin filaments flow into the A bands and the H zone is stuffed up, the I bands shorten, the Z line comes in contact with the A bands.
- The viable using pressure of contraction is the actin-myosin linkages which rely on ATP hydrolysis via the myosin.
- In sliding theory myosin and actin were the main blocks for the muscle contraction, by the above points sliding theory is approved.

Note: When this sarcomere gets shorter, the muscle containing them also gets shortened concerning it which results in muscle contraction. Striated muscle consists of myofibrils, myofibrils consist of sarcomeres. Sarcomere consists of thin and thick protein known as myofilaments. Thick contains myosin and thin contain filaments – collectively known as contractile proteins.