Cardiac Muscle Tissue Analysis

If we are exploring the anatomy of the heart, then it might make sense to begin exploring the outside, or superficial structures first and work our way in from there. With that said then, we begin with the most superficial layer - the pericardium. The pericardium is essentially a multi-layered membranous sac that surrounds and protects the heart. The pericardium does this by maintaining the hearts position within the mediastinum and preventing the heart from over stretching during vigorous workloads. With that said, the pericardium does provide adequate room for the movement produced with the increased force and speed of contraction that the heart exhibits during physical activity (Tortora, G.J., & Derrickson, B., 2017, p. 697). As previously

It is known simply as cardiac muscle tissue. The name may be simple, but cardiac muscle tissue is anything but simple and it deserves an entire section on its own. Cardiac muscle tissue is striated much like skeletal muscle tissue, but is different in that cardiac muscle fibers are shorter and exhibit a “branching” appearance (refer to figure 1.2). Cardiac muscle fibers are also similar to skeletal muscle in that they contain all of the same arrangements of actin and myosin, and the same “bands”, “zones”, and “Z discs” that you would find in skeletal muscle (Tortora, G.J., & Derrickson, B., 2017, p. 709). With that said, there is another notable unique feature to cardiac muscle tissue – it contains intercalated discs, which are essentially irregular transverse thickenings of the sarcolemma that are located at the end of the muscle fibers. These discs are what connect the neighbouring muscle fibers to one another. “The discs contain desmosomes, which hold the fibers together, and gap junctions, which allow muscle action potentials to conduct from one muscle fiber to its neighbours. Gap junctions allow the entire myocardium of the atria or the ventricles to contract as single, coordinated unit.” (Tortora, G.J., & Derrickson, B., 2017, p. 709) (Refer to figure 1.2). These muscle fibers are stimulated by what is known as an intrinsic conduction system – discussed later – as well by action potentials via the autonomic motor neurons that innervate the cardiac muscle tissue (Endocardium: Definition & Function, 2017). With this information, we can then conclude that the contraction of cardiac muscle tissue is an involuntary action. Cardiac muscle fibers themselves are organized in bundles that “swirl” in a slightly diagonal or oblique direction around the heart and when stimulated by the aforementioned, are responsible for the strong