1. Peak systolic pressures in the ventricle, conus and arterial arches differ by 1 or 2 mm. Hg only, and are reached at the same time. Pulse pressures are largest in the ventricle and smallest in the arterial arches, though their relationship to one another is variable and depends partly on heart rate.
2. The conus continues to contract after relaxation of the ventricle. Blood flow from the heart occurs during four-fifths of the cardiac cycle and stops with the closure of the valves at the top of the conus.
3. Volume changes in the conus are 5-10% of those seen in the ventricle. The conus is filled early in ventricular systole before the peak pressure is reached. The ventricle does 20 to 40 times more work than the conus in ejecting blood from the heart.
4. The conus does not serve a depulsating function or make a major contribution to blood outflow from the heart in anurans.
- Copyright © 1965 The Company of Biologists Ltd.