Schematic of cardiorespiratory coupling. The bidirectional arrows between each limit cycle (blue (left), respiratory and red (right), cardiac) represent the reciprocal coupling scheme between respiration and autonomic, cardiac rhythms, which are depicted as harmonics (here the cardiac: respiratory rhythm is 4:1 entrainment). Multiple mechanisms mediate the respiratory influence on the cardiac cycle, whereas a single mechanism mediates the influence of the cardiac/sympathetic activity onthe respiratory cycle. The proposed mechanism is through baror eceptors and their beat-to-beat increase in activity.