Mechanics - Anatomy
The external sex organs, or genitals, of the female make up the vulva. The vulva surrounds the vaginal opening. It includes:
- The mons pubis – the mound of fat and skin that covers the pubic bone. It is where pubic hair grows. It cushions the pubic bone during sex. There are lots of nerve endings here so touching it can be pleasurable for the woman.
- The labia majora are the outer lips. They protect the other external parts. Public hair also grows here. They have sweat and oil glands, and nerve endings. The inner side of them are smooth and hairless. They are formed from the same tissue that forms the scrotum in a male.
- The labia minora are the inner lips, with a hood like cover at the top, to protect the clitoris. They have lots of nerve endings, sweat and oil glands. The labia mirora protect the vaginal opening and urethral opening. They help to stop germs getting in. The urethra is the tube women urinate (pee) from.
- The perineum is the smooth skin from the labia to the anus. It is sensitive to touch.
- The clitoris at the top of the labia. It contains erectile tissue, like the male’s penis. It has lots of nerve endings. Its only function is sexual pleasure. When it is touched or stimulated it expands with blood and swells. It is pleasurable to touch and rub.
Females can see their own external organs if they place a mirror below their vulva.
The anus is where faeces (solid waste / “poo”) comes out. The anus can be a sensitive area.
Most of a woman’s reproductive organs are internal, and out of sight.
- The vagina is like a tube. It’s about 4 inches long. It stretches out during sex as that is where the male’s penis goes. It is where the male’s semen is ejaculated. The vagina is also the passage that the blood from a woman’s period passes down. During childbirth, the baby passes out of the woman’s body through this passageway.
- At the top of the vagina is the cervix. It is the opening to the uterus.
- The uterus is shaped like a pear. Sperm swim up from the vagina. The woman’s eggs travel down the fallopian tubes, once a month. The sperm go through the cervix and into the uterus. If the sperm meets and fertilises an egg in the fallopian tubes the fertilised egg (zygote) implants itself in the uterus. This is where it grows into an embryo and then a foetus, during pregnancy.
The uterus has a lining called the endimetrium. This lining nourishes the fertilised egg. If the egg isn’t fertilised that month the lining comes out of the woman’s body as her period.
- The fallopian tubes connect the ovaries to the uterus. The two ovaries sit on either side of the uterus. The eggs or ova are stored in the ovaries. The ovaries also produce the female sex hormones.
- Breasts are not actually reproductive organs. They are secondary sex characteristics. They come in different shapes and sizes. Their function is to produce milk to feed babies. They are sensitive and can be very pleasurable to touch.
The external male sex organs are the penis, and scrotum – which contains the testicles or testes (balls).
The penis has three functions – passing semen, passing urine and giving sexual pleasure. The penis is made up of three cylinders which are made from spongy tissue, nerves and blood vessels. The penis does not contain any muscle or bone.
The testicles hang behind the penis in a sack of skin called the scrotum. From puberty onwards, the testicles produce about 70 million sperm every day.
They also produce the hormone testosterone although the amount they produce gets less as a man gets older. They are suspended by the spermatic cord, which contains a vas deferens, blood vessels and nerves.
Each sperm takes about three months to develop. A sperm is five one hundredths of a millimetre long – it is the smallest human cell. A sperm has a head, a middle and a tail. The head contains 23 chromosomes and is capped with an enzyme that allows it to get inside a woman’s egg. The middle contains fuel or energy which allows the sperm to move and the tail directs the sperm towards the egg.
Testosterone is the most important male sex hormone. Testosterone produces the physical changes that happen as young boys go through puberty, such as the increase in the size of the penis and testicles, and also hair on the face and body. Testosterone also helps the testicles to make sperm.
Do I measure up?
Penises come in all shapes, sizes, lengths and colours. Some are straight. Some have a bend in them. There is sometimes loose skin on the shaft of the penis – this is called a foreskin. In some cultures this skin is removed just after birth or during childhood in an operation called a circumcision. This affects the way the penis looks but does not affect the way the penis works.
You should know…
- The penis should hang slightly to one side
- One testicle should be higher than the other
- One testicle is larger than the other
- Erections can come and go at embarrassing moments – this is particularly true during puberty
- Penises vary in size and shape. The adult penis is usually between 6cm and 10cm long when soft and 12cm to 19cm long when hard.
Intersex is when someone is born with sex chromosomes, genitals or other sexual characteristics that are neither totally male or totally female.
Intersex is a term used to describe a wide range of biological variance conditions.An example is appearing female on the outside but having mostly male typical reproductive anatomy on the inside, genitals that are inbetween what we expect males and females to have, such as a very large clitoris or very small penis, or a scrotum that has divided and has formed more like labia.
Around 1 in 2000 children will be born this way. Some variations show up at puberty, or later in life e.g. when trying, and failing to have a baby.