Human Reproductive Systems

Humans reproduce sexually, which means a new person is made when a sperm cell (from the father) joins with an egg cell (from the mother). This joining is called fertilisation.

For this to be possible, the body needs structures that:

• make the sex cells (gametes) — sperm in the male, eggs in the female,
• bring the gametes together so fertilisation can happen, and
• protect and feed the new baby as it develops.

That is exactly what the male and female reproductive systems are for. For spec 3.8 you need to know the parts of each system, what each part does, and how its structure is adapted to that function — so always try to link a feature to a job.

Exam tip. A "gamete" is a sex cell. The male gamete is the sperm; the female gamete is the egg (ovum). Examiners often ask you to name these, so learn the word gamete.

The male reproductive system makes sperm and delivers them into the female. Here is the system labelled:

Here is what each part does and how it is adapted:

Part	Function	How it is adapted
Testes (singular: testis)	Make sperm and the male hormone testosterone	Contain many tiny tubes with a large surface to produce huge numbers of sperm
Scrotum	The skin bag/sac that holds the testes outside the body	Keeps the testes slightly cooler than body temperature, which is best for making sperm
Sperm ducts	Carry sperm from the testes towards the urethra	Muscular tubes that push sperm along
Prostate gland	Adds fluid to the sperm to make semen	The fluid nourishes the sperm and helps them swim
Urethra	The tube that carries sperm (and urine) out through the penis	A single tube to the outside; carries semen during reproduction
Penis	Delivers sperm into the vagina of the female	Becomes firm so it can pass sperm deep inside, close to the egg's route

Exam tip. Be precise about the testes: they make both the sperm and the hormone testosterone. Many students forget the hormone.

The female reproductive system makes eggs (ova), and is where fertilisation happens and where a baby develops. Here is the system labelled:

Here is what each part does and how it is adapted:

Part	Function	How it is adapted
Ovaries	Make eggs (ova) and the hormones oestrogen and progesterone	Release one mature egg about every month
Oviducts (fallopian tubes)	Carry the egg to the uterus; the site of fertilisation	Lined with tiny hairs (cilia) and muscle that waft the egg towards the uterus
Uterus (womb)	Where a fertilised egg implants and the baby develops	A thick muscular wall that can stretch as the baby grows; a soft lining for the embryo to attach to
Cervix	The ring of muscle at the base of the uterus	Stays closed during pregnancy to hold the baby in; widens during birth
Vagina	The muscular tube that receives the penis and sperm, and through which the baby is born	Stretchy and muscular

Exam tip. Fertilisation happens in the oviduct (fallopian tube) — not in the uterus and not in the ovary. This is a very common marking point.

Spec 3.8 is about adaptation — how the structure of each part suits its function. Here are the links examiners reward most:

• Scrotum. It hangs the testes outside the main body so they are kept slightly cooler than 37 °C. Sperm are made best at this slightly lower temperature.
• Testes. They contain many coiled tubes, giving a large area to make millions of sperm, and they also release testosterone.
• Oviduct. Its inside is lined with tiny moving hairs (cilia) and muscle. These waft and push the egg along towards the uterus — and because it is a narrow tube, sperm and egg are likely to meet here for fertilisation.
• Uterus. Its thick muscular wall can stretch as the baby grows and then contract powerfully to push the baby out during birth. Its soft lining lets the early embryo implant.
• Cervix. A ring of muscle that stays tightly closed during pregnancy to keep the baby safely inside, then opens (dilates) during birth.
• Penis and vagina. Both are muscular and able to change shape so that sperm can be passed deep inside, close to the egg's route — improving the chance of fertilisation.

A simple way to remember the journey of the gametes:

1. Sperm made in the testes → along the sperm ducts → mixed with prostate fluid → out through the urethra in the penis.
2. Sperm enter the vagina, swim through the cervix and uterus, and up into the oviduct.
3. An egg is released from an ovary into the oviduct.
4. Fertilisation happens in the oviduct, and the fertilised egg moves to the uterus to develop.

Exam tip. When a question says "explain how … is adapted", always pair the feature with the reason — e.g. "the uterus has a thick muscular wall so that it can stretch as the baby grows and push it out at birth".

It helps to see the two systems as a team with complementary jobs:

System	Makes	Hormones	Main delivery/development job
Male	Sperm in the testes	Testosterone	Delivers sperm into the female via the penis
Female	Eggs in the ovaries	Oestrogen and progesterone	Provides the site of fertilisation (oviduct) and grows the baby in the uterus

So:

• the male system is mainly about making and delivering sperm, while
• the female system is about making eggs, allowing fertilisation, and supporting pregnancy.

Exam tip. A common 4–6 mark question asks you to "describe the parts of the male/female reproductive system and their functions". Score full marks by naming each part and giving its job — and remember the testes make a hormone as well as sperm, and the ovaries make two hormones as well as eggs.