How does your body respond to stress? In this experiment, we explore how the autonomic nervous system regulates heart rate in “stressful” situations—like submerging your hand in ice-cold water!
Our nervous system isn’t just in our heads—it runs throughout the entire body. This extensive network allows the brain to coordinate far-flung bodily functions. Think of times when you’ve felt anxious or stressed: you may experience a racing heart, sweating, and that “butterflies in your stomach” feeling. The body prepares you for action! Now think of how you feel after a huge holiday meal—tired and relaxed, almost lulled into a restful state. Your body and brain interact continuously, modulating responses to keep everything running smoothly. In this experiment, we’ll create brief, safe stressors to observe how the body’s autonomic nervous system responds. We’ll use an ice-water bath (the "Ice Water Test"), to determine if this is a "fight or flight" or a "rest and digest" response.
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How does your heart rate change? Was it dramatic? Does it vary between trials or individuals? Discuss how these findings align with either sympathetic vs. parasympathetic control.
Our hearts beat continuously to power our circulatory system, and if we listen closely, we can actually see and hear the electrical impulses that drive each contraction.
Discover the natural reflex in humans and mammals triggered by water immersion
