What is a contractile unit of muscle. Reticulum pulls the ends of the muscle towards each other. Glycogen shortens by releasing glucose molecules and the ends of the shorter glycogen pull on the m bands anchored to the sarcolemma.
The t tubule plus the two terminal cisternae make up a physiological structure known as the triad. In skeletal muscle, there are two terminal cisternae located with each t tubule in muscle cells. The third tnc binds calcium ions. Several other proteins help form the structure of the myofibril.
Both troponin and tropomyosin help control the myosin-actin interactions involved in contraction. Another tnt binds to tropomyosin and helps position it on actin.
The action potential leads to muscle contraction. Calcium ions are released from the triad in order to initiate contraction and keep muscle contraction smooth and regular.
What is the muscle that allows you to shrug your shoulders. Once the calcium ions are released, an action potential will depolarize the cell membrane and propagate throughout the muscle fibers.