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Viewed through a microscope, cardiac muscle cells are roughly rectangular, measuring 100–150μm by 30–40μm. [9] Individual cardiac muscle cells are joined at their ends by intercalated discs to form long fibers. Each cell contains myofibrils, specialized protein contractile fibers of actin and myosin that slide past each other
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 ...
[4] [5] Skeletal muscle cells and cardiac muscle cells both contain myofibrils and sarcomeres and form a striated muscle tissue. [6] Cardiac muscle cells form the cardiac muscle in the walls of the heart chambers, and have a single central nucleus. [7] Cardiac muscle cells are joined to neighboring cells by intercalated discs, and when joined ...
Cardiac muscle has some similarities to neurons and skeletal muscle, as well as important unique properties. Like a neuron, a given myocardial cell has a negative membrane potential when at rest. Stimulation above a threshold value induces the opening of voltage-gated ion channels and a flood of cations into the cell.
The two main myofilaments in cardiac (and skeletal) muscle are actin and myosin. Ca 2+ binds to a protein called troponin , which is bound to the actin filament. This binding causes a shape change in the troponin which exposes areas on the actin , to which the head of the myosin filament binds.
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 entities -- including 13 Russian and 11 Chinese ones, were targeted by the Commerce Department for a host of reasons, including support for Russia's chemical and biological weapons programs ...
The LVAD is the most common device applied to a defective heart (it is sufficient in most cases; the right side of the heart is then often able to make use of the heavily increased blood flow), but when the pulmonary arterial resistance is high, then an (additional) right ventricular assist device (RVAD) might be necessary to resolve the ...