Penis

The penis is an organ of the body which is part of both the reproductive system and the urinary system of male humans and some animals. Here, we are looking at the penis in humans.

File:Male anatomy en.svg

Anatomy of the Male reproductive system

Parts of the penis

On the outside, a penis is mostly straight, although sometimes it may curve slightly to one side. The structure is made up of the following parts:

• Glans - This is the dark red part of the penis, shaped like a bell or an acorn. It is normally covered by the foreskin.
• Foreskin - The skin that covers the glans. It provides protection and can be pulled back to urinate. It also grows with an erection.
• Urethra - The tube which runs through the middle of the penis and carries urine out when you pee.
• Spongy body - Properly called the Corpus spongiosum, this is the spongy protection which surrounds the urethra.
• Corpus cavernosum - The spongy tissue underneath the penile skin. It contains lots of pockets which fill with blood and make the penis swell during an erection.
• Frenulum - A very small muscle which connects the foreskin to the glans.

Erection

When excited, the corpus cavernosum fills with blood, causing the penis to swell and the glans to become more red. This is an erection, although commonly, some people call it a "hard-on" or a "stiffy". When the penis is not erect, it is said to be flaccid (floppy).

In some cases, when erect, the penis is tilted up, down, or to one side. This is normal. Sometimes (but rarely), the angle of the penis is so high or so low, that sexual intercourse is difficult or painful. If this happens, an operation may be needed to put this right.

Functions (what it can do)

Reproduction

Within the reproductive system, when erect, the penis serves to enter the vagina and deposit sperm there, which fertilizes a human egg, which in turn, becomes a new human baby.

Urination

As part of the urinary system, the function of the penis is to transport urine to the outside. This process is called urination. Urination is achieved because the penis is connected (via the urethra to the bladder).

Hygiene

Under the foreskin, a substance called Smegma can build up. This is made up of dead skin cells, fluid made by glands in the penis and remains of urine and semen (when produced). For proper hygiene, it is necessary to clean this area regularly. To do this, the foreskin can be pulled back in older children and adults - only by the person themselves and it must not be forced as this can cause injury. This should be done whilst in the bath or shower. The foreskin should never be pulled back in young children and babies as it's attached to the glans until they're between 7 and 10 years old - A good rule to remember for this is "If intact, don't retract. Only clean what is seen."

Size

The size of someone's penis has absolutely no effect on how much pleasure they get from sexual intercourse, nor does it affect whether a person is fertile or not.

There is no "normal" size. Generally, most adult penises will measure between 6cm (2.3 inches) and 10cm (3.95 inches) when flaccid. When erect, they will be between roughly 13.5cm (5.31 inches) and 16.5cm (6.49 inches). Many cases exist where they have been much bigger or smaller than this, but this does not mean that they are not normal. Despite this, many men are not comfortable with the size of their penis. It is important to understand that there is no way to change it, other than by having an operation. This can be dangerous, painful, unnecessary and sometimes, expensive.

The only time the penis will naturally get smaller is when it is cold. It will shrink and sometimes, retract so it's hard to see.

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