Histology of skeletal muscle fibers

Muscle fiber shape

-Long, elongated cylindrical cells

-Can be 30-40 cm in length

-Multinucleate

Sarcolemma

-Membrane that surrounds the muscle cell

Sarcoplasm

-The cytosol of the muscle cells

-Contains myofibrils

Myofibrils

-Responsible for the contraction of muscles

-Attached to sarcolemma at each end of the muscle cell

-Made of myofilaments (actin and myosin)

Actin

-Myofilament

-Thin protein fillaments

-Slide during contraction

-Arranged in repeating units called SARCOMERES

Myosin

-Myofilament

-Thick protein filaments

-Stationary

-Have heads

-Arranged in repeating units called SARCOMERES

Sarcomere

-Main functional unit of muscle fibers

Transverse (T) tubules

-Play role in transmitting action potentials to the cells

-Role in regulating cellular calcium concentration

Sarcoplasmic reticulum

-Surrounds a myofibril

-Houses calcium

Terminal cisterna

The "end"of the sarcoplasmic reticulum closest to the T tubule

-Sticks out

-Holds the most calcium

Triad

SR + T tubule + terminal cisterna

Myoglobin

Oxygen transport and storage within muscle cells

Multinucleate

Contains multiple nuclei per cell