Your heart starts racing, your mouth goes dry and sweat beads on your forehead. We've all been there, caught in a moment of stress. When you encounter a situation that threatens your safety, your brain must make a critical decision—how to react to the danger at hand.
This is a phenomenon my colleagues and I explore in the program Michael Mosley: Wonders of the Human Body on Channel 5, the late doctor and presenter's final TV series. He died in June this year. A team of us from Bangor University took Michael out of his normal comfort zone to complete an activity with a very high potential risk.
We then monitored his body to measure his stress response . He was no stranger to putting his body to the test to help viewers at home understand their own bodies. Response to stress starts in the hypothalamus, the brain's command center.
Once the hypothalamus decides on a course of action, it activates the sympathetic nervous system. It's a bit like the body's accelerator pedal, revving up your internal engines to prepare for action. The signal from your brain travels to the adrenal glands , located just above your kidneys.
These glands release adrenaline, a hormone many of us are familiar with. Adrenaline is responsible for many of the physical changes you experience during stress, such as increased heart rate and rapid breathing. As adrenaline floods your system, your body gears up for fight or flight.
Blood flow increases, delivering more oxygen and energy to your muscles and brai.