(a) Describe the structure of a sarcomere and indicate the relationship of the sarcomere to the myofilament. (b) Explain the sliding filament theory of contraction inlcuding a relaxed and a contracted sarcomere
STRUCTURE OF A SARCOMERE
The sarcoplasm of a muscle cell contains numerous "little threads" called myofibrils. They extend lengthwise down the muscle fiber. The myofibrils are the contractile elements of a skeletal muscle cell. They are, in turn, made up of even smaller structures called myofilaments. There are two types of myofilaments: thin filaments and thick filaments. The contraction of a muscle occurs when the thin and thick filaments slide past each other and overlap to a great degree.
However, the myofilaments inside a myofibril do not extend the entire length of the muscle fiber. Rather, they are arranged in compartmental units called "sarcomeres." These are the basic functional unit of the contracting muscle fiber. The ends of the sarcomere are marked by a thick line called the Z disc. This is what separates one sarcomere from another. Extending from the Z ...
Sacromere and sliding filament theory are both discussed in this solution.