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Xochitecatl [ʃot͡ʃiˈtekat͡ɬ] is a pre-Columbian archaeological site located in the Mexican State of Tlaxcala, 18 km southwest of Tlaxcala city. [1] The major architecture dates to the Middle Preclassic Period (1000–400 BC) but occupation continued, with one major interruption, until the Late Classic , when the site was abandoned.
Sinus node dysfunction also known as sick sinus syndrome is a group of irregular heartbeat conditions caused by faulty electrical signals of the heart. When the heart's sinoatrial node is defective, the heart's rhythms become abnormal—typically too slow or exhibiting pauses in its function or a combination, and very rarely faster than normal ...
The action potential passes along the cell membrane causing the cell to contract, therefore the activity of the sinoatrial node results in a resting heart rate of roughly 60–100 beats per minute. All cardiac muscle cells are electrically linked to one another, by intercalated discs which allow the action potential to pass from one cell to the ...
This rate can be altered, however, by nerves that work to either increase heart rate (sympathetic nerves) or decrease it (parasympathetic nerves), as the body's oxygen demands change. Ultimately, muscle contraction revolves around a charged atom (ion) , calcium (Ca 2+ ) , [ 3 ] which is responsible for converting the electrical energy of the ...
Further down the electrical conducting system of the heart is the Bundle of His. The left and right bundle branches, and the Purkinje fibers, will also produce a spontaneous action potential at a rate of 30–40 beats per minute, so if the SA and AV node both fail to function, these cells can become pacemakers. These cells will be initiating ...
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.
Cardiotoxicity is the occurrence of heart dysfunction as electric or muscle damage, resulting in heart toxicity. [1] This can cause heart failure, arrhythmia, myocarditis, and cardiomyopathy in patients. [2] Some effects are reversible, while in others, permanent damage requiring further treatment may arise.
Endocardial cushions, or atrioventricular cushions, refer to a subset of cells in the development of the heart that play a vital role in the proper formation of the heart septa. They develop on the atrioventricular canal [2] and conotruncal region of the bulbus cordis. [3] During heart development, the heart starts out as a tube. As heart ...