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A molecule, called adenosine triphosphate (ATP) which is produced by an intracellular structure called a mitochondrion, is then used, as a source of energy, to help move the myosin head, carrying the actin. As a result, the actin slides across the myosin filament shortening the muscle. This is called a power stroke.
The heart muscle may become inflamed in a condition called myocarditis, [46] most commonly caused by a viral infection [47] but sometimes caused by the body's own immune system. [48] Heart muscle can also be damaged by drugs such as alcohol, long standing high blood pressure or hypertension, or persistent abnormal heart racing. [49]
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. [2] Fascia adherens are anchoring sites for actin, and connect to the closest sarcomere. [3]
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 skeletal muscle pump. The skeletal muscle pump or musculovenous pump is a collection of skeletal muscles that aid the heart in the circulation of blood. It is especially important in increasing venous return to the heart, [1] but may also play a role in arterial blood flow.
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Respiratory pump - Intrapleural pressure decreases during inspiration and abdominal pressure increases, squeezing local abdominal veins, allowing thoracic veins to expand and increase blood flow towards the right atrium. Skeletal muscle pump - In the deep veins of the legs, surrounding muscles squeeze veins and pump blood back towards the heart ...