ALFRED PASIEKA / SCIENCE PHOTO LIBRARY ALFRED PASIEKA / SCIENCE PHOTO LIBRARY
Adrenaline. Polarized light micrograph of crystals of adrenaline (epinephrine). This is a hormone produced in the adrenal glands above the kidneys. Adrenaline is normally present in blood in small quantities. However, in times of stress large quantities are secreted into the blood- stream. Adrenaline widens the airways of the lungs, constricts small blood vessels and liberates sugar stored in the liver. This makes the muscles work harder and produce a "fight or flight" response. Adrenaline used as a drug expands the bronchioles in acute asthma attacks, or to stimulate the heart in cases of anaphylactic shock. Magnification: 50x.
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