How Does the Brain Work? And How Does the Nervous System Work? How do you remember the way to your friend's house? Why do your eyes blink without you ever thinking about it? Where do dreams come from?

What Is the Respiratory System? When we breathe, the respiratory system takes in oxygen and sends out carbon dioxide. The cells in our bodies need fresh oxygen to stay alive. As cells do their jobs, ...

What Does the Heart Do? The heart is a pump, usually beating about 60 to 100 times per minute. With each heartbeat, the heart sends blood throughout our bodies, carrying oxygen to every cell. After ...

What Is a Perforated Eardrum? A perforated eardrum is a tear or hole in the ear's tympanic membrane (the eardrum). A perforated (PER-fer-ate-id) eardrum can hurt, but most heal in a few days to weeks.

Testicular torsion is an emergency condition. It happens when the spermatic cord, which provides blood flow to the testicle, rotates and becomes twisted. The twisting cuts off the testicle's blood ...

Coughing is a healthy reflex that helps clear the airways. A severe cough or one that lasts more than a week requires a medical checkup. But many coughs are caused by a virus that just needs to run ...

Doctors use certain milestones to tell if a preschooler is developing as expected. There's a wide range of what's considered normal, so some children gain skills earlier or later than others. Kids who ...

When Are Kids Ready to Toilet Train? Many parents are unsure about when to start toilet training or "potty training." Not all kids are ready at the same age, so it's important to watch your child for ...

What Does the Heart & Circulatory System Do? If you've ever wondered how your heart works, this movie has the answer. And special thanks to the Fred J. Brotherton Charitable Foundation for supporting ...

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 ...

The male reproductive system is made up of the parts inside and outside the body that help a male make a baby. Both the male and female reproductive system are needed for this. The male reproductive ...

How much do you know about the urinary system, which makes pee? Find out by taking this quiz!