Through the interactions between the sympathetic and parasympathetic nervous system. Here’s how it works: -When you inhale (whether through the mouth or the nose), the diaphragm moves down because the lunges expand. Your heart gets a little bit bigger in that expanded space. As a consequence, whatever blood is in there is now moving slower in that larger volume. There’s a little group of neurons, the Sinoatrial Node in the heart, that pays attention to the blood flow in the heart. It will send a signal up to the brain that blood is moving more slowly through the heart. The … Continue reading Control your heart rate directly to calm or to be more alert