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Autoimmune diseases occur when the immune system destroys its own healthy tissues. When this occurs, white blood cells cannot distinguish between pathogens and normal cells.
The first documented use of surgical anesthesia in the United States was in Connecticut in 1844.
Only one in 10 cancer deaths is caused by the primary tumor. The vast majority of cancer mortality is caused by cells breaking away from the main tumor and metastasizing to other parts of the body, such as the brain, bones, or liver.
The familiar sounds of your heart are made by the heart's valves as they open and close.
According to the American College of Allergy, Asthma & Immunology, more than 50 million Americans have some kind of food allergy. Food allergies affect between 4 and 6% of children, and 4% of adults, according to the CDC. The most common food allergies include shellfish, peanuts, walnuts, fish, eggs, milk, and soy.