Question: how oxygenated blood returns to the heart from the lungs
[{'answer': 'pulmonary circulation'}, {'provenance': [{'wikipedia_id': '598465', 'title': 'Pulmonary circulation', 'start_paragraph_id': 0, 'start_character': 0, 'end_paragraph_id': 0, 'end_character': 0, 'bleu_score': 1.0, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 15989548530285987167}, 'section': 'Section::::Abstract.'}]}, {}, {'provenance': [{'wikipedia_id': '598465', 'title': 'Pulmonary circulation', 'start_paragraph_id': 7, 'start_character': 0, 'end_paragraph_id': 7, 'end_character': 303, 'bleu_score': 0.957870874785216, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 15989548530285987167}, 'section': 'Section::::Structure.:Lungs.\n'}]}, {'provenance': [{'wikipedia_id': '598465', 'title': 'Pulmonary circulation', 'start_paragraph_id': 9, 'start_character': 0, 'end_paragraph_id': 9, 'end_character': 447, 'bleu_score': 0.972407137066537, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 15989548530285987167}, 'section': 'Section::::Structure.:Veins.\n'}]}, {'provenance': [{'wikipedia_id': '3997', 'title': 'Blood', 'section': 'Section::::Physiology.:Oxygen transport.\n', 'start_paragraph_id': 54, 'end_paragraph_id': 54, 'meta': {'evidence_span': ['. Under normal conditions in adult humans at rest, hemoglobin in blood leaving the lungs is about 9899% saturated with oxygen, achieving an oxygen delivery between 950 and 1150 ml/', 'per mm\xa0Hg partial pressure of oxygen (about 100\xa0mm\xa0Hg in arteries). With the exception of pulmonary and umbilical arteries and their corresponding veins, arteries carry oxygenated blood away from the heart and deliver it to the body via arterioles and capillaries, where the oxygen is consumed; afterwards, venules and veins carry deoxygenated blood back to the heart. Under normal conditions in adult humans at rest, hemoglobin in blood leaving the lungs is about 9899% saturated with oxygen, achieving an oxygen delivery between 950 and 1150 ml/']}}]}, {'provenance': [{'wikipedia_id': '598465', 'title': 'Pulmonary circulation', 'section': 'Section::::Structure.:Lungs.\n', 'start_paragraph_id': 7, 'end_paragraph_id': 7, 'meta': {'evidence_span': ['the right ventricle through the pulmonary valve and into the main pulmonary artery. The pulmonary arteries carry deoxygenated blood to the lungs, where carbon dioxide is released and oxygen is picked up during respiration. Arteries are further divided into very fine capillaries which are extremely thin-walled. The pulmonary vein returns oxygenated blood to the left atrium of the heart. The oxygenated blood then leaves the lungs through pulmonary veins, which return it to the left heart, completing the pulmonary cycle. This blood then enters the left atrium, which pumps', 'n is picked up during respiration. Arteries are further divided into very fine capillaries whic']}}]}]