myofibrilla
Noun: A myofibrilla (plural: myofibrillae or myofibrillas) is one of the many long, thread-like, contractile filaments that are the basic functional units within a striated muscle fiber (cell). These filaments are arranged in parallel bundles and are responsible for muscle contraction. Their repeating pattern of light and dark bands gives striated muscle its characteristic striped appearance.
The term is a technical, scientific word used primarily in the fields of cell biology, anatomy, and physiology. It refers to the specific subcellular structures that generate force in skeletal and cardiac muscle.
- Under a powerful microscope, you can see that a single muscle fiber is packed with thousands of myofibrillae.
- The sliding filament theory of muscle contraction describes how actin and myosin proteins within the myofibrilla interact.
- Each myofibrilla is composed of a chain of sarcomeres, which are its fundamental contractile units.
- The term is often used interchangeably with myofibril, which is the more common and preferred form in modern scientific literature. "Myofibrilla" can be considered a variant.
- It is a component term in the structural hierarchy of muscle: Myofilaments (actin, myosin) → Sarcomere → Myofibril(la) → Muscle Fiber → Muscle Fascicle → Skeletal Muscle.
- Myofibril (n): The standard and more frequently used term for the same structure.
- Myofilament (n): Refers to the individual protein filaments (actin and myosin) that make up a myofibril.
- Sarcomere (n): The basic repeating unit of a myofibril, bordered by Z-discs, where contraction occurs.
- Sarcoplasm (n): The cytoplasm of a muscle fiber that surrounds the myofibrillae.
- Muscle fibril
- Contractile filament (in the context of striated muscle)
The word myofibrilla has a single, precise meaning in biology. It does not have different everyday meanings, idioms, or phrasal verbs associated with it, as it is a specialized anatomical term.
- one of many contractile filaments that make up a striated muscle fiber