Myofibril

Definition

A myofibril is a long, filamentous organelle found within muscle cells that is responsible for the contraction of muscle fibers. It is composed of a series of sarcomeres, which are the basic units of muscle contraction.

Related terms

Sarcomere:

The structural unit of a myofibril in striated muscle, consisting of a dark band and the nearer half of each adjacent pale band.

Actin:

A protein that forms (together with myosin) the contractile filaments of muscle cells, and is also involved in motion in other types of cells.

Myosin:

A fibrous protein that forms (with actin) the contractile filaments of muscle cells and is also involved in motion in other types of cells