## 2. Menstruation and hormones

Girls ovulate from puberty. This releases an egg. These eggs are in a special bag. We call that pouch the follicle. During ovulation, the follicle bursts and the egg is "launched" out. It is thrown from the ovary to the fallopian tube. This egg is then carried to the uterus by the cilia in the fallopian tubes as a kind of undulating transport.

Usually there is no fertilization after ovulation/ovulation, women just don't want to make babies all the time. The egg then disintegrates in the fallopian tube. About 14 days after ovulation (or ovulation), the woman loses that month's uterine lining through the vagina. The uterine lining is no longer needed, because there is no fertilized egg to grow there. When the woman loses blood and mucus, she has her period. You can also say she is menstruating. Menstruation takes place once a month. This is often accompanied by a bit of abdominal pain or nausea. The uterus is cramping and vibrating to get the mucus and blood out.

The woman is fertile around ovulation/ovulation. A live mature egg is then present.

Day 28 to day 4. If no pregnancy hormones are detected and it is releasing all its blood again and the woman is on her period. All the blood that is in the uterus leaves the body through the vagina. Meanwhile, the egg and follicle continue to grow.

Day 4 to day 8. From here, the egg and follicle begin to grow.

Day 14 to 28. The uterine wall slowly fills with blood again. In the meantime, ovulation takes place: the egg explodes from the follicle. On all other days, the piece of the follicle dies and shrivels. The egg is already dead, because it only lives for 12 to 24 hours. At the same time, the uterine wall continues to suck on blood, because there may be a baby.

The day on which a period starts is called the first day of a menstrual cycle. A girl who has her period exactly every 28 days will ovulate on the 14th day. But most girls don't have regular periods: The cycle varies from 26-31 days and sometimes even shorter or longer.

If you have a short cycle, ovulation takes place earlier, for example on the twelfth day. With a longer cycle, ovulation takes place later, for example on the seventeenth day. The period between ovulation and the next menstruation fluctuates somewhat less.
This period usually lasts about 14 days.

A girl has her first period during puberty. A woman is no longer fertile from about the age of fifty. As soon as ovulation stops taking place, menstruation stops. We call this the menopause.

(VWO)

For the VWO students there is something more. They need to know how the pituitary gland controls the process of menstruation. There is a step-by-step plan and a schedule for:

The brain makes FSH, this works on the follicle

The follicle grows

The follicle produces estrogen

The endometrium/lining thickens

When the follicle is large enough, the pituitary gland starts to produce LH

Ovulation (egg in fallopian tube)

After ovulation, the rest of the follicle changes into the yellow body

The yellow body starts to produce progesterone

The egg is fertilized and starts to release its own hormone, which turns on the pregnancy mode.

OR

The yellow body dies due to lack of LH, FSH and pregnancy hormone

No more progesterone, endometrium/lining dies.

This makes you menstruate