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The conduction system consists of specialized heart muscle cells, situated within the myocardium. [3] There is a skeleton of fibrous tissue that surrounds the conduction system which can be seen on an ECG. Dysfunction of the conduction system can cause irregular heart rhythms including rhythms that are too fast or too slow.
First, atrial contraction feeds blood into the ventricles, then ventricular contraction pumps blood out of the heart to the body systems, including the lungs for resupply of oxygen. Cardiac systole is the contraction of the cardiac muscle in response to an electrochemical stimulus to the heart's cells ( cardiomyocytes ).
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 heart is a four-chambered organ consisting of right and left halves, called the right heart and the left heart. The upper two chambers, the left and right atria , are entry points into the heart for blood-flow returning from the circulatory system , while the two lower chambers, the left and right ventricles , perform the contractions that ...
In humans, the heart is approximately the size of a closed fist and is located between the lungs, in the middle compartment of the chest, called the mediastinum. [4] In humans, the heart is divided into four chambers: upper left and right atria and lower left and right ventricles.
The electrical system of the heart is centered on the periodic contraction (squeezing) of the muscle cells that is caused by the cardiac pacemaker located in the sinoatrial node. The study of the electrical aspects is a sub-field of electrophysiology called cardiac electrophysiology and is epitomized with the electrocardiogram (ECG/EKG).
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.
These cells produce an electrical impulse known as a cardiac action potential that travels through the electrical conduction system of the heart, causing it to contract. In a healthy heart, the SA node continuously produces action potentials, setting the rhythm of the heart (sinus rhythm), and so is known as the heart's natural pacemaker.