av and sa node signals or atrioventricular and sinoartial node signal of human heart

allowing aorta arteries arterioles artery atria atrial atrioventricular atrium avn blood body capillaries cells chambers complex deoxygenated electrical endocardium epicardium excitation functions gatekeeper heart human impulse lungs myocardium node organ oxygenated oxygenrich performs primarily pulmonary pump signal signals sinoatrial structure tissue tricuspid variety veins ventricle ventricles ventricular venules