Menstruation

The idea

If the egg is not fertilised, the thick, spongy uterine lining prepared each month is not needed, so it breaks and comes out through the vagina as blood and mucous; this monthly cycle is menstruation.

Ready every month

Every month the uterus gets ready to receive a fertilised egg.

What happens if the egg is not fertilised?

• The prepared lining is not needed and comes out
• The lining stays the same
• The embryo forms anyway

One month in the uterus

Press Next step. This is a schematic diagram.

A monthly cycle

One egg is released each month, so the uterus prepares every month. If the egg is not fertilised the lining is not needed. It breaks and leaves the body through the vagina as blood and mucous. This usually lasts for about two to eight days.

If the egg is not fertilised, the thick, spongy lining of the uterus prepared each month is not needed, so it breaks and comes out through the vagina as blood and mucous. This monthly cycle is menstruation.

Notes

If the egg is not fertilised, the thick, spongy uterine lining breaks and comes out through the vagina as blood and mucous. This monthly cycle is menstruation.

Check yourself

What is menstruation?

Why does the lining of the uterus become thick and spongy each month?

If the egg is not fertilised, what happens to the uterine lining?

• The release of an egg from the ovary. The ovary releases one egg every month. Menstruation is the lining breaking when the egg is not fertilised.
• The monthly breaking of the uterine lining, which comes out through the vagina as blood and mucous — correct. Yes!
• The formation of the embryo. If the egg is not fertilised, no embryo forms, and the lining comes out.
• To make blood and mucous. The lining is required for nourishing the embryo. When the lining is not needed, it comes out as blood and mucous.
• To help the ovary release the egg. The ovary releases an egg every month. The lining is for nourishing an embryo if fertilisation takes place.
• To nourish the embryo if fertilisation takes place — correct. Yes!
• It slowly breaks and comes out through the vagina — correct. Yes!
• It stays thick for nine months. The lining is not needed any longer, so it slowly breaks and comes out.
• It turns into an embryo. An embryo forms from a fertilised egg. If the egg is not fertilised, the lining comes out.