The various regulatory systems in the human body are most certainly interconnected, even if the complete understanding of their interrelation has so far eluded all efforts. Our work focuses on the coupling between heart activity and respiration. Hildebrand postulated a fixed pulse respiration quotient of 4:1, especially during the last two sleeping hours, as healthy. One well known interaction is the respiratory sinus arrhythmia (RSA), a change in the heart rate according to the current position in the respiratory cycle. Another such previously found effect is mainly interpreted according to the well understood physical principle of phase synchronisation. While RSA was suspected to be causal in the emergence of the synchronisation effect, it was shown to be independent. Work on a new coupling effect based in time instead of phase, coordination, begged the question of its relationship to the previously known ones. This talk describes the differences to synchronisation and also shows its independence from RSA.