Detailed information on what teen boys can expect during a physical exam.

Bipolar disorder is a type of depression. A teen with bipolar disorder often has extreme mood swings. These mood swings go beyond the day's normal ups and downs.

Cognitive development means the growth of a child's ability to think and reason. This growth happens differently from ages 6 to 12, and ages 12 to 18.

Bulimia nervosa is an eating disorder. A child with bulimia overeats or binges uncontrollably. This overeating may be followed by self-induced throwing up (purging).

Circumcision is a surgery to remove the skin covering the end of the penis. This is called the foreskin. This surgery is most often done 1 or 2 days after a baby's birth. Read on to learn more about this procedure.

Birth defects may be caused by inherited (genetic) problems or by environmental things, such as exposure to certain toxic substances during pregnancy. Some birth defects can be linked to a direct cause. Other reasons are not as clear.

Detailed information on cystic fibrosis and its effect on the respiratory system.

Detailed information on cystic fibrosis and its effect on the reproductive system.

In the digestive system, cystic fibrosis (CF) mainly affects the pancreas. A child with CF has trouble absorbing fats, as well as some proteins and vitamins.

Detailed information on the genetics involved in cystic fibrosis.