During a single cardiac cycle, the atria and ventricles do not beat simultaneously; the atrial contraction occurs prior to ventricular contraction. This timing delay allows for proper filling of all four chambers of the heart. Recall that the left and right heart pumps function in parallel.  An isolated cardiac muscle cell, beating. Cardiac muscle (heart muscle) is involuntary striated muscle that is found in the walls and histological foundation of the heart, specifically the myocardium. Cardiac muscle is one of three major types of muscle, the others being skeletal and smooth muscle. These three types of muscle all form in the process of myogenesis. The cells that constitute cardiac muscle, called cardiomyocytes or myocardiocytes, contain only three nuclei. CORONARY ARTERY DISEASE (CAD) is the most significant threat to the myocardium, as occlusions in the coronary arteries deprive the myocardium of blood and thus oxygen. When the consequence is MYOCARDIAL INFARCTION, CARDIAC ARREST can result. Myocardial cells thus can contract independent of external stimulation. The myocardial fibers of the atria have a different configuration from those of the ventricles. The CORONARY ARTERIES provide an extensive network to supply blood to the myocardium, which requires about 70 percent of the blood’s oxygen. The normal electrical conduction in the heart allows the impulse that is generated by the sinoatrial node (SA node) of the heart to be propagated to, and stimulate, the cardiac muscle (myocardium).  Atrial fibrillation is the most common cardiac arrhythmia. It impairs cardiac function and increases the risk of stroke. The incidence of atrial fibrillation increases with age. Key treatment issues include deciding when to restore normal sinus rhythm, when to control rate only, and how to prevent thromboembolism. Rate control is the recommended treatment strategy in most patients with atrial fibrillation. Rhythm control is an option for patients in whom rate control is not achievable or who remain symptomatic despite rate control. Myocardium (muscle tissue heart) - definition and function. The MUSCLE tissue that forms the walls of the HEART. Myocardial cells are unique in their structure, blending muscle and NERVE structures so they can both contract and conduct electrical impulses. Myocardial cells thus can contract independent of external stimulation. The myocardial fibers of the atria have a different configuration from those of the ventricles. The CORONARY ARTERIES provide an extensive network to supply blood to the myocardium, which requires about 70 percent of the blood’s oxygen. The most common cause of stroke from an arrhythmia is atrial fibrillation. Atrial fibrillation can cause blood clots to form in the atria (top chamber of the heart) where they can be pumped out of the heart, to the brain, blocking a blood vessel and causing a stroke. Treatment for atrial fibrillation focuses in part on reducing the risk of stroke. Blood clots can form in the heart's upper chambers because of atrial fibrillation, a disorder in which the atria quiver instead of beating effectively. Blood that isn't pumped completely out of the atria when the heart beats may pool and clot. Atrial fibrillation is a source of significant morbidity and mortality because it impairs cardiac function and increases the risk of stroke. Its most important clinical implications are shown in Figure 2. Rate control is the recommended treatment strategy in most patients with atrial fibrillation. Rhythm control is an option for patients in whom rate control is not achievable or who remain symptomatic despite rate control. Coordinated contractions of cardiac muscle cells in the heart propel blood out of the atria and ventricles to the blood vessels of the left/body/systemic and right/lungs/pulmonary circulatory systems. This complex mechanism illustrates systole of the heart. Cardiac muscle is one of three major types of muscle, the others being skeletal and smooth muscle. These three types of muscle all form in the process of myogenesis. The cells that constitute cardiac muscle, called cardiomyocytes or myocardiocytes, contain only three nuclei. Impulses pass from the autorhythmic cardiac cells in the sinoatrial node through atrial myocytes to the atrioventricular node, down the atrioventricular bundle (bundle of His) to the right and left bundle branches and on to the Purkinje fibers. The right side of the heart is the pulmonary circuit pump. Pumps blood through the lungs, where CO 2 is unloaded and O 2 is picked up. The left side of the heart is the systemic circuit pump. Pumps blood to the tissues, delivering O 2 and nutrients and picking up CO 2 and wastes.
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what is atrial myocardial function