The route of circulation in the human heart (a) Left auricle - right auricle - right ventricle - pulmonary artery - lungs - pulmonary veins - Left ventricle - aorta (b) Right auricle - left auricle - right ventricle - pulmonary artery - lungs - pulmonary veins -left ventricle - aorta (c) Right auricle - right ventricle - pulmonary veins - lungs - pulmonary artery - left auricle -left ventricle - aorta (d) Right auricle - right ventricle - pulmonary artery - lungs - pulmonary veins - left auricle - left ventricle - aorta