Did you know you have more than 600 muscles in your body? They do everything from pumping blood throughout your body to helping you lift your heavy backpack. You control some of your muscles, while ...

Both the brain and the spinal cord are protected by bone: the brain by the bones of the skull, and the spinal cord by vertebrae, a set of ring-shaped bones. They're both cushioned by layers of ...

It’s normal for people to masturbate (touch or rub their own genitals because they like the way it feels). Some people do it to relieve stress or tension. It’s nothing to be ashamed of or embarrassed ...

Many things can lead to hearing loss, but often, no cause is found. Hearing loss is more likely if a child: Some hearing problems come on gradually after birth or show up later in life. If you are ...

Smoking is one of the worst things you can do to your body. Yet every single day, some kids and teens start smoking. Why? There's more than just one answer. Some kids may start smoking just because ...

Herd immunity is the idea that when many people are immune to (protected from) a contagious infection, it's harder for that infection to spread in a community. Antibody shots against specific germs ...

We see and hear about hearts everywhere. A long time ago, people even thought that their emotions came from their hearts, maybe because the heart beats faster when a person is scared or excited. Now ...

How Do I Take a Rectal Temperature? The best way to take a temperature in infants and young children is by taking a rectal temperature. Don't worry — it's a simple and safe process.

How Does Air Enter the Respiratory System? Air enters the respiratory system through the nose or the mouth. If it goes in the nostrils (also called nares), the air is warmed and humidified. Tiny hairs ...

What Is Polyarticular Juvenile Idiopathic Arthritis? Polyarticular juvenile idiopathic arthritis is a type of juvenile idiopathic arthritis (JIA). JIA is a group of disorders that causes arthritis ...

Sexually transmitted diseases (STDs) are infections spread from person to person during sex (vaginal, oral, or anal) or close sexual contact. STDs are also called sexually transmitted infections, or ...

Girls have lots of questions about the body changes of puberty. When will my breasts grow? What's the "normal" age to get your first period? Watch this video and find out!