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 ...

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 ...

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 ...

Why are my breasts different sizes? Is there anything I can do about it? It is normal to have different sized breasts. If you have just started developing breasts, one breast may grow more quickly ...

This is a general outline of the milestones on the road to reading success. Keep in mind that kids develop at different paces and spend varying amounts of time at each stage. If you have concerns, ...

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 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 ...

Popsicle panniculitis (pih-NIK-yuh-LITE-iss) is an inflammation of the bottom layer of skin in the cheeks caused by exposure to cold. The bottom layer of our skin, the subcutaneous tissue, is made up ...

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

Walking pneumonia is a less serious form of the lung infection pneumonia. It's often caused by bacteria called Mycoplasma pneumoniae, but other bacteria or viruses can also cause it. Most kids with ...

Alopecia areata (al-uh-PEE-shuh air-ee-AH-tuh) is a condition that causes hair loss on the scalp and sometimes elsewhere on the body, such as the eyebrows and eyelashes. The condition is not ...

What Is Hand, Foot, and Mouth Disease (HFM)? Hand, foot, and mouth disease (HFM) is a common viral infection that causes painful red blisters in the mouth and throat, and on the hands, feet, and ...