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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.
Acute bronchitis is an inflammation of the breathing tubes (bronchi), which causes increased mucus production and other changes. It is usually caused by bacteria or viruses, can be serious in people who have pulmonary or cardiac diseases, and can lead to pneumonia.
The familiar sounds of your heart are made by the heart's valves as they open and close.
The average adult has about 21 square feet of skin.
About 3% of all pregnant women will give birth to twins, which is an increase in rate of nearly 60% since the early 1980s.