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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 ]
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.
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.
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]
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.
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.
The bundle of His (BH) [1]: 58 or His bundle (HB) [1]: 232 (/ h ɪ s / "hiss" [2]) is a collection of heart muscle cells specialized for electrical conduction.As part of the electrical conduction system of the heart, it transmits the electrical impulses from the atrioventricular node (located between the atria and the ventricles) to the point of the apex of the fascicular branches via the ...
Image showing the cardiac pacemaker or SA node, the primary pacemaker within the electrical conduction system of the heart The cardiac pacemaker is the heart 's natural rhythm generator. It employs pacemaker cells that produce electrical impulses, known as cardiac action potentials , which control the rate of contraction of the cardiac muscle ...