Tanisi, Life Sciences, USA, North America Region: 2025 Breakthrough Junior Challenge Popular Vote

Hi. Has this ever been you? I'm sure we've all felt it. Eyes dilating, knees shaking, that sinking pit in your stomach. But did you ever wonder why? Long ago, humans faced daily dangers. Tigers, lions, you name it. Because of this, our bodies developed an involuntary reaction controlled by the sympathetic nervous system. Our body's panic button, aka the fight-or-flight response. Meet Siggy. He's an electrical signal that travels from the brain to your body. Siggy starts at the hypothalamus and drifts down your spinal cord to the signal airport, known as the sympathetic trunk. Signals like Siggy can enter any gate from T1 to L2, the thoracic lumbar vertebrae of your spine. Siggy enters the preganglionic neuronal axon at his gate, attached to the spinal cord to reach the ganglia. The ganglion is a security checkpoint. Here, Siggy hands over a boarding pass at the synapse. His boarding pass is a neurotransmitter called acetylcholine. This creates action potential in the following neuron. The plane, also known as the postganglionic nerve, flies him to his destination, the effector organ. At the organ, Siggy releases another neurotransmitter called norepinephrine, which runs around with excitement. These little things love beta and alpha receptors, which are found on smooth muscle around the body. Alpha receptors vasoconstrict blood vessels found on the skin, stomach, kidneys, and other organs to restrict blood flow to those unneeded areas for survival. Beta receptors vasodilate blood vessels found on the skeletal muscles, like the legs, and widen bronchioles in the lungs, helping you fight or flee. Meanwhile, your adrenal glands, found above your kidneys, release the hormone version of norepinephrine and epinephrine directly through the bloodstream for faster distribution to these receptors. Because of this stress response, all of a sudden your body is hyper-aware of your surroundings, ready to take any action necessary to survive, all within seconds. So next time you're on stage, just remember, at least you're not being chased by a tiger. Even if you were, your body's got your back.