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When cardiomyocytes were transfected with adenoviruses expressing E2F2, cyclins A and E were upregulated, and cardiomyocytes proliferated. [ 22 ] The cessation of the cardiomyocyte cell cycle is believed to be regulated by transcription factors and cyclin dependent kinase inhibitors, although the exact mechanism remains unclear. [ 23 ]
T-tubules (transverse tubules) are extensions of the cell membrane that penetrate into the center of skeletal and cardiac muscle cells.With membranes that contain large concentrations of ion channels, transporters, and pumps, T-tubules permit rapid transmission of the action potential into the cell, and also play an important role in regulating cellular calcium concentration.
Intercalated discs are complex structures that connect adjacent cardiac muscle cells.The three types of cell junction recognised as making up an intercalated disc are desmosomes, fascia adherens junctions, and gap junctions.
The unusual microscopic anatomy of a muscle cell gave rise to its terminology. The cytoplasm in a muscle cell is termed the sarcoplasm; the smooth endoplasmic reticulum of a muscle cell is termed the sarcoplasmic reticulum; and the cell membrane in a muscle cell is termed the sarcolemma. [9]
Cardiac muscle cells (also called cardiomyocytes) are the contractile myocytes of the cardiac muscle. The cells are surrounded by an extracellular matrix produced by supporting fibroblast cells. Specialised modified cardiomyocytes known as pacemaker cells , set the rhythm of the heart contractions.
Image of a myocardial action potential. Effective refractory period in green. In electrocardiography, during a cardiac cycle, once an action potential is initiated, there is a period of time that a new action potential cannot be initiated. This is termed the effective refractory period (ERP) of the tissue.
Cardiac physiology or heart function is the study of healthy, unimpaired function of the heart: involving blood flow; myocardium structure; the electrical conduction system of the heart; the cardiac cycle and cardiac output and how these interact and depend on one another.
Cardiac sarcomere structure featuring troponin T. Troponin T (shortened TnT [1] or TropT) is a part of the troponin complex, which are proteins integral to the contraction of skeletal and heart muscles.