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Anatomy and Function of the Heart Valves What are heart valves? The heart has four chambers: two upper chambers (atria) and two lower chambers (ventricles). Blood passes through a valve before leaving each chamber of the heart. The valves prevent the backward flow of blood

Nightmares and Night Terrors What are night terrors? A night terror is a partial waking from sleep with behaviors such as screaming, kicking, panic, sleep walking, thrashing, or mumbling. They are harmless, and each episode will end in deep sleep. They tend to occur in children

Work and Pregnancy Congratulations on your pregnancy! If you work, you might be wondering if you can continue working throughout your pregnancy. Many women do so without any problems. Pregnancy causes many changes in your body. Your ability to keep working depends on your overall

Breast Pain (Mastalgia) What is mastalgia? Mastalgia is breast pain. There are 2 main types of mastalgia: Cyclical breast pain. The pain is linked to menstrual periods. Noncyclic breast pain. The pain may come from the breast. Or it may come from somewhere else, such as nearby

Polycystic Kidney Disease What is polycystic kidney disease (PKD)? Polycystic kidney disease (PKD) is a rare genetic disorder. It causes many cysts filled with fluid to grow in the kidneys. PKD cysts can impair how the kidneys work. It can lead to kidney failure. PKD is the

Antibiotics What are antibiotics? Antibiotics are powerful medicines used to treat certain bacterial infections. Antibiotics don't cure all infections. And antibiotics that are used when not needed can be harmful. There are 2 main types of germs that cause most infections. These

Water Safety for Parents The importance of water safety Most drownings happen in residential swimming pools. But children can drown in just 1 inch of water (such as in buckets, bathtubs, wading pools, diaper pails, toilets, hot tubs, and spas). In addition, open waters, such as

Smoking and Heart Disease The American Heart Association (AHA) says diseases caused by smoking kill more than 440,000 people in the U.S. each year. Most new smokers are children and teens. Smokers have a higher risk for lung disease and other respiratory problems, such as

Medical Genetics: Types of Genetic Changes The human body has about 20,000 different genes in each cell. Genes are located on chromosomes, which are stick-shaped structures in the middle of the cell (nucleus). Each cell usually has 46 chromosomes grouped in 23 pairs. Each gene

Benign Skin Growths What are benign skin growths? Skin changes as you grow older and are exposed to sunlight, health conditions, trauma, and other environmental changes. Most people have some skin marks, such as freckles and moles. These may multiply or darken over time. Benign