In two spatial dimensions, traveling waves can take the form of target patterns or of spiral waves . Rhythms of life Breathing, circadian rhythms, or the beating of our hearts are natural rhythms of our lives. The heart is a muscle whose tissue acts as an excitable medium. Contraction of this muscle , leading to the pumping of blood, is triggered by an electric wave which propagates across the heart. This wave is sent by the sinoatrial node , which acts as a pacemaker, thereby creating a target pattern.
Ventricular fibrillation occurs when different parts of the heart lose their synchrony.
This condition quickly provokes sudden cardiac death if not arrested. Numerical simulations and models confirm this description of ventricular fibrillation. Waves in bacterial colonies Wave patterns are also observed in colonies of bacteria . These single-cell organisms often communicate by emitting some chemical, called a chemoattractant . Other bacteria can then move in the direction in which the concentration of this chemoattractant increases the fastest, thereby leading to cell aggregation.