Menstruation
When the egg is not fertilised.
No zygote to feed
Each month the uterus gets ready with a thick, blood-rich lining, in case a zygote arrives. This month no zygote came.
What do you think happens to the lining that is not needed?
What this lesson covers
The idea
An unfertilised egg degenerates after about a day, and the thickened, blood-rich uterine lining, no longer needed, sheds and leaves through the vagina with some blood; this is menstruation, lasting 3 to 7 days.
No zygote to feed
Each month the uterus gets ready with a thick, blood-rich lining, in case a zygote arrives. This month no zygote came.
What do you think happens to the lining that is not needed?
- It sheds and leaves the body through the vagina
- It stays and grows even thicker
- It turns into an egg
What happens to the lining
Press Next step. The picture is a simple schematic.
A normal, healthy process
An egg that is not fertilised lasts about a day and then degenerates. The lining is shed with some blood. Menstruation is a sign of a healthy reproductive system. It is not something to be ashamed of.
An unfertilised egg degenerates after about a day. The thickened, blood-rich uterine lining, no longer needed, sheds and leaves through the vagina with some blood. This is menstruation, lasting 3 to 7 days.
Notes
If the egg is not fertilised, it degenerates and the thickened uterine lining sheds through the vagina with some blood: menstruation, lasting 3 to 7 days.
Check yourself
What happens to an egg that is not fertilised?
What is shed in menstruation?
How long does menstruation usually last?
Why is the uterine lining shed?
- It turns into a zygote. A zygote forms only when a sperm fuses with the egg.
- It stays in the oviduct for a month. An unfertilised egg degenerates after about a day.
- It remains viable for about a day and then degenerates — correct. Yes!
- The thickened inner lining of the uterus, with some blood — correct. Yes!
- The ovary. The ovaries stay in the body and keep producing eggs and hormones.
- The oviduct. The oviducts connect each ovary to the uterus and stay in the body.
- About one month. The cycle repeats typically every 21 to 35 days, but menstruation itself usually lasts 3 to 7 days.
- 3 to 7 days — correct. Yes!
- About one day. An unfertilised egg lasts about a day. Menstruation usually lasts 3 to 7 days.
- It is too thin to be kept. The lining had become thick and rich with blood vessels, and it is shed because it is no longer needed.
- Sperm have damaged it. The lining sheds because it is no longer needed.
- It is no longer needed, as there is no zygote to nourish — correct. Yes!