{
 "narration": {
  "S1": {
   "text": "Stage one. A signal starts in the sinoatrial node, high in the right atrium, and spreads across both atria. They contract and push the last part of the filling into the ventricles.",
   "duration": 12.96,
   "cues": [
    {
     "t0": 0.0,
     "t1": 3.7,
     "text": "Stage one. A signal starts in the sinoatrial node,"
    },
    {
     "t0": 3.7,
     "t1": 8.0,
     "text": "high in the right atrium, and spreads across both atria."
    },
    {
     "t0": 8.0,
     "t1": 13.0,
     "text": "They contract and push the last part of the filling into the ventricles."
    }
   ]
  },
  "S2": {
   "text": "Stage two. The signal crosses the atrioventricular node and runs down the septum into the ventricles. They begin to contract. All four valves are closed, so no blood moves yet, and the pressure builds.",
   "duration": 14.2,
   "cues": [
    {
     "t0": 0.0,
     "t1": 7.0,
     "text": "Stage two. The signal crosses the atrioventricular node and runs down the septum into the ventricles."
    },
    {
     "t0": 7.0,
     "t1": 8.71,
     "text": "They begin to contract."
    },
    {
     "t0": 8.71,
     "t1": 12.21,
     "text": "All four valves are closed, so no blood moves yet,"
    },
    {
     "t0": 12.21,
     "t1": 14.0,
     "text": "and the pressure builds."
    }
   ]
  },
  "S3": {
   "text": "Stage three. The pressure opens the pulmonary and aortic valves. The right ventricle sends blood to the lungs, and the left ventricle sends it into the aorta and on to the body.",
   "duration": 11.64,
   "cues": [
    {
     "t0": 0.0,
     "t1": 5.0,
     "text": "Stage three. The pressure opens the pulmonary and aortic valves."
    },
    {
     "t0": 5.0,
     "t1": 7.03,
     "text": "The right ventricle sends blood to the lungs,"
    },
    {
     "t0": 7.03,
     "t1": 10.88,
     "text": "and the left ventricle sends it into the aorta and on to the body."
    }
   ]
  },
  "S4": {
   "text": "Stage four. The ventricles relax. The pulmonary and aortic valves close, so once again all four valves are shut, while the atria keep filling from the veins.",
   "duration": 11.48,
   "cues": [
    {
     "t0": 0.0,
     "t1": 2.21,
     "text": "Stage four. The ventricles relax."
    },
    {
     "t0": 2.21,
     "t1": 5.0,
     "text": "The pulmonary and aortic valves close,"
    },
    {
     "t0": 5.0,
     "t1": 7.79,
     "text": "so once again all four valves are shut,"
    },
    {
     "t0": 7.79,
     "t1": 11.0,
     "text": "while the atria keep filling from the veins."
    }
   ]
  },
  "S5": {
   "text": "Stage five. The tricuspid and mitral valves open, and blood flows from the atria into the ventricles on its own. Most of the filling happens this way, before the atria ever contract.",
   "duration": 12.16,
   "cues": [
    {
     "t0": 0.0,
     "t1": 3.19,
     "text": "Stage five. The tricuspid and mitral valves open,"
    },
    {
     "t0": 3.19,
     "t1": 8.16,
     "text": "and blood flows from the atria into the ventricles on its own."
    },
    {
     "t0": 8.16,
     "t1": 9.98,
     "text": "Most of the filling happens this way,"
    },
    {
     "t0": 9.98,
     "t1": 11.52,
     "text": "before the atria ever contract."
    }
   ]
  },
  "S6": {
   "text": "Stage six. The heart rests and filling slows. Cells in the sinoatrial node slowly charge toward the next signal, and the beat begins again.",
   "duration": 11.56,
   "cues": [
    {
     "t0": 0.0,
     "t1": 3.6,
     "text": "Stage six. The heart rests and filling slows."
    },
    {
     "t0": 4.56,
     "t1": 8.99,
     "text": "Cells in the sinoatrial node slowly charge toward the next signal,"
    },
    {
     "t0": 8.99,
     "t1": 10.8,
     "text": "and the beat begins again."
    }
   ]
  }
 },
 "empty": {
  "S1_L1_flow": true,
  "S4_L1_signal": true,
  "S4_L2_signal": true,
  "S4_L3_signal": true,
  "S4_L4_signal": true,
  "S5_L1_signal": true,
  "S5_L2_signal": true,
  "S5_L3_signal": true,
  "S5_L4_signal": true
 },
 "source_short": {
  "OS1": "OpenStax 19.1",
  "OS2": "OpenStax 19.2",
  "OS3": "OpenStax 19.3",
  "WK1": "Wiggers diagram (Wikipedia)",
  "WK2": "Cardiac cycle (Wikipedia)",
  "WK3": "Aortic arch (Wikipedia)",
  "NH1": "NIH NHLBI",
  "TM1": "TeachMeAnatomy"
 }
}