cardio anatomy - nclex correctly answered to pass

cardio anatomy - layers epicardium - outer myocardium - middle endocardium - innermost pericardial sac surrounds the heart and helps prevent overfilling - 2 layers --> parietal pericardium - visceral pericardium 4 heart chambers right atrium - deoxygenated blood from vena cavas right ventricle - receives blood from RA and pumps into LUNGS left atrium - receives oxygenated blood from lungs left ventricle - largest and most muscular, receives oxygenated blood from lungs from LA and pumps blood systemically via aorta heart valves tricuspid, pulmonary, mitral, aortic SA node pacemaker of the heart 60 - 100 bpm AV node receives electrical impulses from SA node - if SA node fails - 40 - 60 bpm bundle of HIS fibers extending from the AV node to the right and left bundle branches that fire the impulse from the AV node to the Purkinje fibers Purkinje fibers spread depolarization through the ventricles - pacemaker - 20 - 40 bpm when other fail coronary arteries main coronary artery supplies RA and ventricle, inferior portion of LV and posterior septal wall, SA and AV nodes - left main coronary artery consists of 2 major branches, LAD and circumflex - LAD supplies blood to anterior wall and LV, AV septum, apex of lv - circumflex artery