9 min readPathway sheetOften a 5-mark answer with a labelled diagram of the female reproductive system; the placenta and menstruation as 2 or 3-mark questions

The female reproductive system, pregnancy and menstruation

An ovary releases one egg each month. If a sperm fertilises it in the oviduct, the embryo grows in the uterus, fed through the placenta; if not, menstruation follows.

OvariesMake eggs and the hormone oestrogen; one egg is released each month

Site of fertilisationOviduct (fallopian tube)

PlacentaDisc in the uterus wall; passes glucose and oxygen to the embryo and removes its wastes

MenstruationUterus lining leaves as blood and mucus; lasts about 2 to 8 days

Parts of the female reproductive system

Part	Job
Ovaries (two)	Hold thousands of immature eggs from birth; from puberty, one egg is released each month by one of the ovaries; make oestrogen
Oviducts (fallopian tubes)	Carry the egg from the ovary to the uterus; fertilisation takes place here
Uterus (womb)	Elastic, bag-like organ where the embryo grows; its lining becomes thick and spongy every month
Cervix	Narrow lower end of the uterus, opening into the vagina
Vagina	Passage that opens outside; sperms enter here

From fertilisation to birth

1
Sperms enter through the vagina, travel up through the uterus, and reach the oviduct.
2★
A sperm meets the egg in the oviduct and fertilisation takes place, forming a zygote.
3
The zygote divides as it moves down, and the embryo implants in the thick lining of the uterus.
4★
The placenta forms: a disc in the uterus wall with villi on the embryo's side and blood spaces on the mother's side.
5
Across its large surface, glucose and oxygen pass from the mother to the embryo, and wastes pass from the embryo into the mother's blood.
6
After about nine months, the baby is born through rhythmic contractions of the muscles of the uterus.

★ key step

What happens if the egg is not fertilised

1
Every month, the uterus prepares a thick, spongy lining, rich in blood, to receive and feed a zygote.
2
The released egg lives for about one day.
3
If it is not fertilised, the lining is not needed and slowly breaks down.
4★
It comes out through the vagina as blood and mucus: this is menstruation, which lasts about 2 to 8 days.
5
The cycle repeats roughly every month.

★ key step

How to draw the human female reproductive system

Draw an upside-down, pear-shaped uterus in the centre.
From each upper corner, draw a curved tube, the oviduct (fallopian tube), ending in a funnel near an oval ovary.
Mark the narrow lower end of the uterus as the cervix.
Below the cervix, draw a tube, the vagina, opening to the outside.
Label: ovary, oviduct, uterus, cervix, vagina.

In real life

Pregnant women are advised a nutritious diet, often with iron and folic acid tablets, because the baby gets its food from the mother's blood through the placenta. Clean sanitary pads and good hygiene during menstruation help prevent infections.

Exam angle

2 marks: “What is the placenta? Write its job.” A disc embedded in the uterus wall, with villi on the embryo's side and blood spaces on the mother's side. It passes glucose and oxygen to the embryo and removes its wastes.

3 marks: “What happens to the lining of the uterus when the egg is not fertilised?” The thick, blood-rich lining is not needed; it breaks down slowly and leaves through the vagina as blood and mucus (menstruation, about 2 to 8 days); the cycle repeats roughly every month.

5 marks: “Draw a labelled diagram of the human female reproductive system. How does the embryo get nourishment inside the mother's body?” Labelled ovary, oviduct, uterus, cervix, vagina; fertilisation in the oviduct; implantation; placenta with villi and blood spaces; glucose and oxygen in, wastes out; about nine months.

Remember it

Path of the egg: Ovary → Oviduct → Uterus → Cervix → Vagina. Fertilisation happens on the way, in the oviduct.