Myofibrils
Myofibrils
Myofibrils (/maɪəˈfaɪbrɪlz/; from the Greek myo, meaning "muscle", and fibril, meaning "small fiber") are the basic rod-like units of a muscle cell. They are composed of long proteins including actin, myosin, and titin, and other proteins that hold them together.
Structure
Myofibrils are cylindrical structures that run the length of a muscle fiber. They are composed of repeating sections, known as sarcomeres, which are the basic functional units of the muscle. Each sarcomere is composed of long, fibrous proteins that slide past each other when the muscles contract and relax.
Function
The primary function of myofibrils is to perform muscle contraction. This is achieved through a process known as the sliding filament theory, where the actin and myosin filaments within the sarcomeres of myofibrils slide past one another, creating a contraction that changes both the length and the shape of the cell.
Related Terms
- Actin: A protein that forms the thin filament in a sarcomere and works in conjunction with myosin to produce muscle contraction.
- Myosin: A protein that forms the thick filament in a sarcomere and works in conjunction with actin to produce muscle contraction.
- Sarcomere: The basic contractile unit of muscle fiber.
- Sliding filament theory: The theory that explains muscle contraction by the sliding motion of actin and myosin filaments.
External links
- Medical encyclopedia article on Myofibrils
- Wikipedia's article - Myofibrils
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