Q. Why is adrenaline called the 'fight or flight' hormone?
A. If you get a fright from a person in a dark alley, for example, adrenaline speeds up the breathing rate and the heartbeat. It also increases the muscles ability to take in sugar such as glucose. So adrenaline gets the body ready to either fight the person or to run away (flight) if they are too big.
Q. How does caffeine in Coke and coffee act to dehydrate you?
A. Caffeine interferes with a hormone that regulates water balance in the kidneys. Instead of some water being reabsorbed into our bloodstream, that water is lost in urine.
Q. What are the Islets of Langerhans?
A. They are cells in the adrenal glands near the kidneys that make the hormone called insulin which regulates blood sugar levels.
Q. What are 'goose bumps'?
A. When we are cold, the tiny muscles attached to our hairs contract and the hairs stand up. This forms an insulating 'blanket' of warm air close to our skin to keep us warm. The tiny contracted muscles also rise up and form bumps on the skin.
Q. Why do some people's lips turn blue in winter?
A. When it is cold, our blood vessels constrict or get smaller to keep in the warmth inside our bodies. Because of this, the redness of our blood is not so easily seen, and our lips appear bluish.
Q. How does shivering keep us warm?
A. Muscles that contracting quickly are rubbing against other body parts creating heat from friction. Also muscle cells are respiring more and producing more energy for heat.