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 ...

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 ...

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!

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 ...

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 ...

How much do you know about your digestive system? Find out by taking this quiz!

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 ...

Flat feet are feet that do not have an arch. The middle of the foot touches the ground. Feet with no arches is the main sign of flat feet. Sometimes, flat feet can cause foot, ankle, or knee pain.

An erection is when the penis gets hard because sponge-like tissue in it fills with blood. Erections tend to make the penis get bigger and stand away from the body. Erections can go away on their own ...

Parents do everything they can to protect their children. But sadly, many kids have gone through trauma. A trauma is any event that is deeply upsetting, scary, or harmful. Things like abuse, violence, ...

Answering kids' questions about sex is a job many parents don’t look forward to. It may feel awkward when it comes to talking about puberty and where babies come from. But don’t avoid these topics.

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 ...