Male Anatomy: What's Up Down There?

Courtesy of Nickelodeon

Drake Bell

What makes boys different from girls?

You can tell the difference between boys and girls just by looking at them. Boys have unique organs, both inside and out, that identify them as male.

What's on the outside?

The penis is on the outside, and it has two functions. The urethra runs through the penis to connect the bladder to the outside. That's how men pee.

The penis is also a sexual organ, which becomes erect when a boy is sexually excited. The blood vessels and tissues of the penis fill with blood and the penis grows longer, extends upward, and becomes hard. It's only then that a boy can have sexual intercourse. When he has an orgasm, about a teaspoon of semen is ejaculated (squirted out). Semen is the fluid that carries the sperm.

Beneath the penis is a sac called the scrotum. The scrotum holds the testicles, one on each side. The testicles are small and round; that's why testicles are also called "balls." The base of the penis and the scrotum are covered by pubic hair.

What's on the inside?

The testicles are located in the scrotum, the sac underneath the penis. The testicles produce the male hormone testosterone. This hormone causes typical guy characteristics such as the rough hair that grows on his face and a deep voice. The testicles also produce sperm, the male sex cells. Sperm are essential for reproduction. When a sperm joins with an egg inside a female body, a pregnancy has begun.

The testicles hang in a sac outside the body because they work better when they're cooler than normal body temperature. If the testicles become overheated, they may not be able to produce sperm.

The prostate gland is another uniquely male organ located inside a boy's body. The prostate produces the fluid called semen. The sperm are carried out of the body when they are ejaculated along with semen.