Question: where does the blood in the right atrium come from
[{'answer': 'venous circulation', 'provenance': [{'wikipedia_id': '1317242', 'title': 'Atrium (heart)', 'start_paragraph_id': 1, 'start_character': 287, 'end_paragraph_id': 1, 'end_character': 305, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]