FIGHT OR FLIGHT?

A car races out of a driveway inches in front of you, or something crashes in another room while you are home alone.In an instant, your heart pounds, your neck prickles, and you breathe harder. You may get goosebumps. These physical reactions, which happen automatically, are a reaction to danger. In humans and many other organisms, muscles undergo immediate changes. These begin after the brain
floods the body with dozens of emergency chemicals, called hormones, which set off a chain reaction of muscle activities. When certain hormones are released, heart muscles pump more oxygenated blood to muscles in the arms and legs. These muscles tighten to gather energy that may be needed to fly from the danger or fight it directly. Capillaries in the skin constrict so that blood will go to the muscles instead of the skin. The loss of blood near the skin causes chills and goose bumps in scary or stressful situations.
Eye muscles expand. As a result, widened pupils take in more light so that you can see better. Muscles near the lungs relax to let in more oxygen so that breathing speeds up. At the same time, digestive muscles slow down. This increases energy and blood flow to the muscles needed in an emergency. The flight or fight response is an instinct that helps all animals, including humans, to survive dangerous situations.