Muscle Fiber Structure and Function

Set of flashcards covering the structure and function of muscle fibers, including myofibrils and the anatomy of skeletal muscle.

Muscle Fiber

Long, cylindrical, multinucleate muscle cells; plasma membrane called sarcolemma.

Sarcoplasm

The cytoplasm of muscle fibers, containing high amounts of glycogen, myoglobin, and myofibrils.

Myofibrils

Contractile elements of muscle cells that run parallel and fill 80% of cell volume.

Striations

Alternating dark A bands and light I bands that create the striated appearance of skeletal muscle.

A Band

The dark band in striated muscle, made of thick myosin filaments.

I Band

The light band in striated muscle, containing thin actin filaments.

Z Disc

The boundary structure within a sarcomere where actin filaments are anchored.

Sarcomere

The functional unit of a muscle fiber, defined by the area between two Z discs.

H Zone

The region within the A band where no thin filaments overlap with thick filaments.

M Line

The line in the middle of the A band where thick myosin filaments are anchored.