Muscle Notes #10 (Sarcomere)

The functional unit involved in contraction and movement of skeletal muscle tissue.

• Sacromeres line up along the myofibril protein structures. (Found inside muscle cells)

• Movement is caused by thick and thin myofilaments in the myofibril sliding together.

Long, cylindrical muscle cells with multiple nuclei.

Muscle fiber plasma membrane.

Muscle fiber cytoplasm.

• Has many glycosomes (glycogen storage)

• Contains myoglobin

Thick myofilaments

Thin myofilaments

Modified ER of muscle tissue.

Invaginations of the sacrolemma, found deep inside muscle cells.

One T Tubule sandwiched between two sarcoplasmic reticula.

Tube-like cells mostly filled with stretchy rod-like threads.

• Muscle cells contain these

• 80% of cell volume, 1000s in each cell

• Contain many sacromeres (contractile units)

Orderly arrangement of 2 sizes of __ within the sarcomere.

• Sarcomere cross section is a hexagon arrangement.

• 1 thick filament surrounded by six thin filaments.

Act like bodyguards controlling when actin and myosin interact.

• Rod-shaped protein which spirals around actin

• Block myosin binding sites on actin

• Unblocks myosin when troponin changes shape

• Globular protein

• Changes shape when bound to calcium

Elastic filament on ends of myosin which resists excessive stretching.

Attaches thin actins to sarcolemma.