Sarcomere
Sarcomere
Sarcomere (/sɑːrkoʊmiːr/; from the Greek sarx meaning "flesh" and meros meaning "part") is the basic unit of a muscle's myofibril. Sarcomeres are responsible for the striated appearance of skeletal muscle and cardiac muscle.
Structure
A sarcomere is composed of long, fibrous proteins that slide past each other when the muscles contract and relax. Two of the important proteins are actin and myosin, which form thick and thin filaments, respectively. The region of the sarcomere containing the thick filaments is the A band. The region of the sarcomere containing only thin filaments is the I band.
Function
The primary function of the sarcomere is to convert chemical energy in the form of ATP to mechanical energy, resulting in muscle contraction. This process is known as the sliding filament theory.
Related Terms
- Myofibril: The basic rod-like unit of a muscle. Myofibrils are composed of long proteins including actin, myosin, and titin, and other proteins that hold them together.
- Actin: A protein that forms the thin filament in a sarcomere; responsible for muscle contraction in combination with myosin.
- Myosin: A protein that forms the thick filament in a sarcomere; works in conjunction with actin to enable muscle contraction.
- Sliding filament theory: The theory that explains muscle contraction based on the sliding of the myosin and actin filaments over each other.
External links
- Medical encyclopedia article on Sarcomere
- Wikipedia's article - Sarcomere
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