sa nodes signal in the heart or sinoartial node signal

aorta arteries arterioles artery atria atrioventricular atrium blood body capillaries cells chambers cluster cycle deoxygenated electrical endocardium epicardium heart human impulse lungs myocardium node organ oxygenated oxygenrich pulmonary pump signal signals sinoatrial tissue tricuspid veins ventricle ventricles venules