Touching a hot pan and yanking your hand away: Pain and reflexes Jumping up and down: Equilibrium and depth perception. Drinking water on a hot day: Dehydration and lowering your temperature. Sneezing: reaction to dust, smut, grains, or allergies. Blushing: The rising of your blood temperature and nervousness. Hitting your head on the top of the car as you get into it: Pain and depth perception. Breathing harder during a jog: increased heart rate, blood flow, and less oxygen.