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The action potential travels from one location in the cell to another, but ion flow across the membrane occurs only at the nodes of Ranvier. As a result, the action potential signal jumps along the axon, from node to node, rather than propagating smoothly, as they do in axons that lack a myelin sheath.
Atrioventricular block (AV block) is a type of heart block that occurs when the electrical signal traveling from the atria, or the upper chambers of the heart, to ventricles, or the lower chambers of the heart, is impaired. Normally, the sinoatrial node (SA node) produces an electrical
A chest radiograph, chest X-ray (CXR), or chest film is a projection radiograph of the chest used to diagnose conditions affecting the chest, its contents, and nearby structures. Chest radiographs are the most common film taken in medicine.
Myocardial perfusion imaging or scanning (also referred to as MPI or MPS) is a nuclear medicine procedure that illustrates the function of the heart muscle (). [1]It evaluates many heart conditions, such as coronary artery disease (CAD), [2] hypertrophic cardiomyopathy and heart wall motion abnormalities.
Chest X-ray: On chest X-ray (CXR), transposition of the great vessels typically shows a cardio-mediastinal silhouette appearing as an "egg on a string", in which the enlarged heart represents an egg on its side and the narrowed, atrophic thymus of the superior mediastinum represents the string. [4]
Isolated heart conduction system showing atrioventricular node. The AV node receives two inputs from the right atrium: posteriorly, via the crista terminalis, and anteriorly, via the interatrial septum. [8] Contraction of heart muscle cells requires depolarization and repolarization of their cell membranes. Movement of ions across cell ...
This junction marks the inferior end of the superior vena cava, the continuation below that point being considered part of the heart. For purposes of radiographic visualization, the most reliable indicator of junction location is to find the carina , then observe the vertebrae it overlies.
Apical four chamber ultrasound view of heart. Transthoracic echocardiography (TTE) uses ultrasonic waves for continuous heart chamber and blood movement visualization. It is the most commonly used imaging tool for diagnosing heart problems, as it allows non-invasive visualization of the heart and the blood flow through the heart, using a technique known as Doppler.