Depicted in Figure 1 is the sarcomere, which is the basic contractile unit of striated muscle. Sarcomeres are organized in series to make up a myofibril.
sarcomere. a contractile unit of muscle.
sarcomeresCardiac muscle is similar to skeletal muscle, another major muscle type, in that it possesses contractile units known as sarcomeres; this feature, however, also distinguishes it from smooth muscle, the third muscle type.
sarcomeresThe smallest contractile unit of skeletal muscle is the muscle fiber or myofiber, which is a long cylindrical cell that contains many nuclei, mitochondria, and sarcomeres (Figure 1) [58].
The sarcomere is the functional unit of the muscle fiber. The sarcomere itself is bundled within the myofibril that runs the entire length of the muscle fiber and attaches to the sarcolemma at its end. As myofibrils contract, the entire muscle cell contracts.
The myocardium is the muscular wall of the heart, or the heart muscle. It contracts to pump blood out of the heart and then relaxes as the heart refills with returning blood. The myocardium's smooth outer membrane is called the epicardium. Its inner lining is called the endocardium.
Cardiac muscles are involuntary muscles. They are involved in continuous rhythmic contraction and relaxation. Cardiomyocytes or the cardiac cells are uninucleate, cylindrical, and elongated.
Voluntary muscles are skeletal muscles that contract and relax under conscious control. These muscles attach to bones and regulate movement of the body. Involuntary muscles, on the other hand, are not under conscious control.Sep 24, 2021