myofibril
Noun A myofibril is one of the long, thread-like, contractile structures found within a striated muscle fiber (cell). These cylindrical organelles are composed of repeating units called sarcomeres, which contain the proteins actin and myosin. The arrangement of these proteins gives myofibrils, and thus the entire muscle fiber, a striped or striated appearance. Myofibrils are the fundamental units responsible for muscle contraction.
The term "myofibril" is used in biological, anatomical, and physiological contexts to describe the internal, functional components of muscle cells. It is a specific, scientific term.
Examples - Under a microscope, you can see that each myofibril is made up of a chain of sarcomeres. - The force of a muscle contraction is generated by the sliding of filaments within the myofibrils. - Damage to the myofibrils can result from intense exercise.
- Myofibrillar: (Adjective) Pertaining to or of the nature of myofibrils.
- Myofibrillar protein synthesis is a key process in muscle growth and repair.
- Myofibrilla: An alternate, less common singular form.
- Myofibrils: The standard plural form.
- Sarcomere: (Noun) The basic repeating contractile unit of a myofibril.
- Sarcoplasm: (Noun) The cytoplasm of a muscle fiber that surrounds the myofibrils.
- Muscle fibril
- Myofibrilla (rare)
The word "myofibril" refers exclusively to the subcellular structures within striated muscle fibers, which include both skeletal and cardiac muscle. It is not used for the contractile elements in smooth muscle.
- one of many contractile filaments that make up a striated muscle fiber