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Penises & testicles, My Body

Penises and testicles

The penis has two main functions; urination (carrying urine or wee out of the body) and ejaculation (delivering semen from the testicles.) The testicles are where semen is produced and stored, and where testosterone is produced. 

The penis has two main functions; urination (carrying urine out of the body) and ejaculation (carrying semen out of the body). 

The testicles also have two main functions; they are where sperm is produced and stored, and where testosterone is produced.


The external parts

The penis is made up of the shaft and the glans (also known as the head). Between the shaft and the head is the corona, which is a ridge that separates the two. 

At birth, the penis is covered by the foreskin, which is a hood of loose skin that surrounds the penis. The underside of the penis has a frenulum (or frenum) which connects the foreskin to the base of the glans. Read more about foreskins here.

The scrotum is the sac of skin which hangs at the base of the penis. The scrotum holds the testicles and keeps them at the right temperature. If it is too cold, a muscle called the cremaster constricts, which pulls the scrotum and testicles closer to the body. If it is too warm, the cremaster relaxes and allows the scrotum and testicles to hang further away from the body. The scrotum is very sensitive, so any impact can be painful, but if it is touched gently it can feel good during masturbation or sex.

Further back from the penis and testicles is the anus, which is the opening to the rectum. The anus is very sensitive, which means it can feel good to touch during masturbation or sex. 

A diagram of the anatomy of the penis, showing the urethra, glans, corona of glans, frenulum, foreskin and urethral opening.
Illustration of the inside of a male penis
A diagram of the male reproductive system, showing the bladder, prostate, urethra, penis, vas deferens, epididymis and testicles.

The internal parts

Running along the inside of the penis is the urethra. This is the tube which carries urine out of the body from the bladder. During ejaculation, the urethra carries semen out of the body from the testicles.

The testicles hang outside of the body inside the scrotum. They can be the same size, one can be bigger than the other, and they can hang at different heights. The testicles produce sperm, as well as a hormone called ‘testosterone’ which plays a role in puberty.

The epididymis is a tube where sperm matures. It connects each testicle to each vas deferens, and holds sperm before ejaculation.

A vas deferens is a long, narrow tube that carries sperm from the epididymis to the seminal vesicles when ejaculation happens. There are two of them, each one connected to each epididymis.

Seminal vesicles are 2 small organs that produce semen, the fluid that sperm moves around in. They are located below the bladder.

The prostate gland makes a fluid that helps sperm move. It’s about the size of a walnut. The prostate gland is sensitive to pressure or touch in a way that many people find pleasurable.

The Cowper’s glands produce a fluid called pre-ejaculate or precum. This fluid prepares the urethra for ejaculation. It reduces friction so semen can move more easily. The Cowper’s glands are under the prostate and attach to the urethra. They’re also called bulbourethral glands.

The cremaster is a muscle that moves the scrotum and testicles closer to the body, for example during arousal or when cold.

How it works during arousal


An erection is when the spongy tissue of the penis fills with blood and becomes hard. Erections can happen if you are thinking about or experiencing something arousing, and also if erogenous zones are stimulated.

What are erogenous zones?

An erogenous zone is an area of your body which is very sensitive, and can produce a sexual response when it is touched. An important part of discovering your sexuality is learning which parts of your body feel good to be touched. 

Common examples of erogenous zones for people with penises include the penis, scrotum, anus, prostate and nipples. Common examples of erogenous zones for people with vulvas include the vulva, vagina, anus and nipples. They can also include, but are not limited to, other areas of your body such as your neck, ears, back, hips and thighs.

When the penis is erect and is stimulated, it can cause pleasurable sensations which might lead to ejaculation. 


Ejaculation is the passing of semen from the penis through the urethra as a result of an orgasm. It can happen during sex, masturbation and also arousal without any physical stimulation. It can also happen if a person has an orgasm while they are asleep, which is called a nocturnal emission or ‘wet dream’. This is completely common and usually starts happening during puberty, which is also when it is more frequent. People with vulvas can also experience wet dreams.

Ejaculation is part of natural conception because if the semen that is ejaculated comes into contact with a person’s vagina, usually during sex, it can result in pregnancy. As a result, it is important to use contraception when having sex that involves a penis to avoid unwanted pregnancy. 

There are lots of different types of contraception that can protect against pregnancy, but the only one that a person with a penis can use is a condom. Condoms (and femidoms) are also the only types of contraception which protect against STIs as well as pregnancy. 

Read more about contraception.

Read more about conception and pregnancy.

Looking after your penis and testicles

How to wash your penis and testicles

You should gently wash your penis and testicles with warm water once every day, and if you have a foreskin, pull it back gently and wash underneath. If you don’t keep your penis clean a yellowish-white creamy substance called smegma will start to build up on the head of your penis, and under your foreskin.

Smegma is a natural lubricant that keeps your penis moist, but if it starts to build up it can have an unpleasant smell (a bit like cheese) and become a breeding ground for bacteria. This can then cause balanitis (redness and swelling of the head of the penis).

People with foreskins need to be extra careful about washing smegma away. Try washing carefully under your foreskin, and see if the yellowish stuff disappears. You might like to use some un-perfumed soap or shower gel (to avoid irritation), and gently rub it with your fingers. Once it goes, make sure you wash under your foreskin every day, to avoid smegma building up again.

Do I need to groom?

Pubic hair grows around the top of your penis and testicles and can sometimes grow around your stomach or the top of your thighs. It can be coarse or fine, straight or curly, dark or light – it’s all completely normal.

Some people like to remove some or all of their pubic hair. Lots of people also choose to leave their pubic hair exactly the way it is. Everyone is different and the way you choose to keep your pubic hair is entirely up to you. Bear in mind though that pubic hair does exist for a reason. It is designed to provide protection from bacteria and reduce friction during penetrative sex. Removing it can result in soreness and ingrown hairs.

If you do decide to remove your pubic hair, be very careful as the skin around your genitals is delicate. Here are some tips to remove your pubic hair safely:

  • Make sure the area you are shaving or trimming is clean, as this reduces the chances of infection or ingrown hairs. Use warm water, as this softens the hair and skin, making abrasions less likely.
  • Make sure you can see what you are doing. A hand-held or pedestal mirror can help with this. 
  • Trim before you shave. The safest way of doing this is with an electric razor with a guard. Make sure you trim in the direction that the hair grows to avoid snagging. If you are using scissors to do this, make sure they are clean and sharp, as blunt scissors are less effective and more likely to cause injury. Cut with the points of the scissors pointing away from your body, and don’t cut too close to the skin. 
  • If you are using a razor, make sure it is new, sharp and of good quality, as this will reduce the chance of injury and infection. Do not use the same razor for your face or anywhere else on your body, as this can cause infection. Make sure to use a sensitive shaving cream, then pull your skin taught and shave gently in the direction that the hair grows. 
  • After shaving, clean the area with warm water and pat dry. Apply a gentle moisturiser or lotion to prevent irritation. It is a good idea to use something unscented as this is often less irritating to the skin. 
  • If at any point during grooming you cut yourself, stop immediately. Clean the area with soap and warm water to disinfect it, and apply pressure to stop the bleeding. Apply a plaster if necessary and replace regularly until the cut heals, making sure to keep it clean. Don’t continue grooming the area until it has had time to heal, which can be from a few days to a few weeks.

Penis and testicle health

In order to judge if something isn’t right, it’s really important to get to know your penis and testicles and what is ‘normal’ for your body so that you can identify when there are any changes.

There are lots of healthy, normal ways that penises and testicles can change and these changes can be associated with puberty or even hormone changes.

The general rule is that if you notice a change that involves discomfort, pain, discharge or smell that is not normal for you, then speak to your GP, school nurse or visit a sexual health clinic. Healthcare professionals are used to answering all kinds of questions about penises and testicles. You can talk everything through and it’s confidential.

Lumps and bumps

The penis can have lumps and bumps and in most cases these are harmless, such as Forcyde spots (which are enlarged oil glands) or milia (which are caused by a buildup of keratin). 

Lumps and sores can also be caused by poor hygiene, sex, sexually transmitted infections (STIs) or skin conditions such as molluscum contagiosum (a viral skin infection), and in very rare cases penile cancer. 

You can read more about the causes of lumps and bumps on the penis on the NHS Choices website. If you are worried or notice something that isn’t quite right you should speak to a doctor or nurse.

It’s common to get spots and bumps on the scrotum, and they are often completely harmless. However, it’s important to get to know your testicles, so that you can tell if something doesn’t feel quite right.

How to examine your penis and testicles

It’s a good idea to examine your testicles when you’re in the bath or shower. Support your scrotum in the palm of your hand, and become familiar with the size and weight of each testicle. Examine each testicle by rolling it between your fingers and thumb. Your testicles should feel smooth, so gently feel for lumps, swellings, or changes in firmness. Check for lumps on the surface or within the body of each testicle.

If you spot something unusual

If you notice a lump, or something doesn’t feel quite right, or you get sharp pains or a dull ache in your testicles, it’s important to see a doctor or nurse. Other reasons to go to the doctor are if you get a sensation of heaviness in your scrotum, or a dull ache in your lower abdomen or groin.

There are a number of things that can cause lumps, swelling or pain in the testicles such as some STIs, fluid or cysts but the main reason you are encouraged to check your testicles is because of testicular cancer. While testicular cancer is rare (around 2,200 men/people with penises are diagnosed each year in the UK) it is most common in younger men/people with penises, which is why checking your testicles is a great habit to get into.

Find out more about testicular cancer: You can read more about the symptoms of testicular cancer and what to look for and about testicular cancer incidence by age.

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