What exactly happens in the heart when its flooded with too much adrenaline?
Adrenaline from the nervous system lands on receptors of cardiac myocytes (heart-muscle cells), and this causes calcium channels in the membranes of those cells to open. Calcium ions rush into the heart cells and this causes the heart muscle to contract. If it’s a massive overwhelming storm of adrenaline, calcium keeps pouring into the cells and the muscle just can’t relax. There is this specially adapted system of muscle and nerve tissue in the heart—the sinoatrial (SA) node, the atrioventricular node, and the Purkinje fibers—which sets the rhythm of the heart. If this system is overwhelmed with adrenaline, the heart can go into abnormal rhythms that are not compatible with life. If one of those is triggered, you will drop dead.
