In comparison with the enormous cylinders of skeletal muscle, cardiac muscle cells, or cardiomyocytes, are considerably shorter with much smaller diameters. Cardiac muscle also demonstrates striations, the alternating sample of dark A bands and light I bands attributed to the exact arrangement of the myofilaments and fibrils which are organized in sarcomeres along the size of the cell (Figure 19.17a). These contractile components are nearly identical to skeletal muscle. T (transverse) tubules penetrate from the surface plasma membrane, the sarcolemma, to the interior of the cell, permitting the electrical impulse to reach the interior. The T tubules are solely discovered at the Z discs, whereas in skeletal muscle, they're found on the junction of the A and i bands. Therefore, there are one-half as many T tubules in cardiac muscle as in skeletal muscle. In addition, the sarcoplasmic reticulum stores few calcium ions, so many of the calcium ions must come from outside the cells. Here is my page - https://pion.ru/bitrix/redirect.php?goto=http://knowledge.thinkingstorm.com/UserProfile/tabid/57/userId/2906108/Default.aspx