Imagine swimming in a lake on a hot summer day. The water is quite warm, but the wind is strong and the moment you leave the water you feel chilly and get â€œgoosebumps.â€ So you change clothes and move inside to warm up. You make a nice cup of tea, get under a blanket and switch on the radio. Suddenly, you hear a song from a long time ago, the song your grandmother used to sing to you when you were a child. Again, you feel a chill on your back and again, you get goosebumps. Why?
Goosebumps are tiny elevations of the skin that resemble the skin of poultry after the feathers have been plucked. These bumps are caused by a contraction of miniature muscles that are attached to each hair. Each contracting muscle creates a shallow depression on the skin surface, which causes the surrounding area to protrude. The contraction also causes the hair to stand up whenever the body feels cold. In animals with a thick hair coat this rising of hair expands the layer of air that serves as insulation. The thicker the hair layer, the more heat is retained.
In addition to cold, the hair will also stand up in many animals when they feel threatened–in a cat being attacked by a dog, for example. People also tend to experience goosebumps during emotional situations.
In some situations, the body releases a stress hormone called adrenaline. Adrenaline not only causes the contraction of skin muscles but also influences many other body reactions. In humans, adrenaline is often released when we feel cold or afraid, but also if we are under stress and feel strong emotions, such as anger or excitement. Other signs of adrenaline release include tears, sweaty palms, trembling hands, an increase in blood pressure, a racing heart or the feeling of â€˜butterfliesâ€™ in the stomach.