Menstrual Cycle

I'm finding it hard to understand this. I've read the book but it's too basic, it doesn't explain LH,FSH etc.

Can someone explain it to me.

Thanks in advance.

Reply 1

LittleMissyMe.x

2

The pituitary gland makes FSH which stimulates an egg to mature and oestrogen to be produced
Oestrogen is made by the ovaries and stops the further production of FSH.
Oestrogen then stimulates the production of LH and prepares the womb lining to develop for the fertilised egg.
LH is made by the pituitary gland and stimulates the egg to be released- also known as ovulation.

The PITUITARY GLAND is in the brain and is also known as the master gland (do not refer to it as this in an exam!)
FSH is FOLLICLE STIMULATING HORMONE which is made at the beginning of the menstrual cycle.
LH is the LUTEINIZING HORMONE which causes the egg to be released at (or about) day 14, (you don't really need to know a lot about this specific hormone at GCSE level)

I hope I helped! Just memorise this and you should be fine :smile:

Reply 2

niaphonic

10

Also to add to the good explanation above - what helped me when I was first learning it was to draw a diagram with arrows, so that you remember the order of things, and which hormone inhibits/stimulates which, otherwise it can get confusing!

Reply 3

zed963

OP

16

Original post by niaphonic

Also to add to the good explanation above - what helped me when I was first learning it was to draw a diagram with arrows, so that you remember the order of things, and which hormone inhibits/stimulates which, otherwise it can get confusing!

What's the job of oestrogen and progesterone?

Reply 4

niaphonic

10

Think of the 28 day cycle.

Days 1-5 = menstruation, so the lining of the uterus (endometrium) breaks down and is lost. This is because Progesterone stops being produced, and its job is to maintain the thickness of the endometrium in preparation for a fertilised egg to implant, should the woman become pregnant.
During this time, FSH is also secreted by the pituitary gland, which in turn stimulates Oestrogen to be secreted by the developing 'egg' in the ovary.

Days 6-13 = Oestrogen's job is to repair the endometrium following menstruation, to it's previous thickness. It also inhibits the secretion of FSH, and stimulates the secretion of LH.

Day 14 = LH then stimulates the release of an egg from the ovary at ovulation. It also stimulates the secretion of Progesterone.

Days 15-28 = Progesterone then does its job, maintaining the thickness of the endometrium while the egg travels down the fallopian tube in anticipation of fertilisation and potential pregnancy. It also inhibits LH (therefore inhibiting ovulation) and FSH. By day 28, Progesterone production will have decreased, so the endometrium is no longer being maintained, it breaks down and is lost during menstruation. Because Progesterone is no longer being produced, FSH is no longer inhibited so it is secreted by the pituitary gland once again, and the cycle continues!

Hope that helped a little?

Reply 5

zed963

OP

16

Original post by niaphonic

Think of the 28 day cycle.

Days 1-5 = menstruation, so the lining of the uterus (endometrium) breaks down and is lost. This is because Progesterone stops being produced, and its job is to maintain the thickness of the endometrium in preparation for a fertilised egg to implant, should the woman become pregnant.
During this time, FSH is also secreted by the pituitary gland, which in turn stimulates Oestrogen to be secreted by the developing 'egg' in the ovary.

Days 6-13 = Oestrogen's job is to repair the endometrium following menstruation, to it's previous thickness. It also inhibits the secretion of FSH, and stimulates the secretion of LH.

Day 14 = LH then stimulates the release of an egg from the ovary at ovulation. It also stimulates the secretion of Progesterone.

Days 15-28 = Progesterone then does its job, maintaining the thickness of the endometrium while the egg travels down the fallopian tube in anticipation of fertilisation and potential pregnancy. It also inhibits LH (therefore inhibiting ovulation) and FSH. By day 28, Progesterone production will have decreased, so the endometrium is no longer being maintained, it breaks down and is lost during menstruation. Because Progesterone is no longer being produced, FSH is no longer inhibited so it is secreted by the pituitary gland once again, and the cycle continues!

Hope that helped a little?

Yes that helped. Seriously, is that all there is to it? I don't know why I was banging my head over it for so long.

Thanks.

Reply 6

niaphonic

10

You're welcome! yeah that's the basic outline of it.

You can then read up on more detail on the development of the egg inside the ovary which will explain why Progesterone decreases at the end of the cycle - the simplified version is that inside the ovary, an egg begins its development as an 'oocyte' within an ovarian follicle. FSH is involved in the development of these follicles, and it's these follicles that release the Oestrogen. Once the mature egg is released from the follicle at Day 14, the empty follicle itself is now called the Corpus Luteum - this hangs around inside the ovary and secretes the Progesterone between Day 15-28. The corpus luteum eventually shrivels up by the end of the cycle, so once it's gone, it obviously can't keep producing Progesterone so the cycle begins again with FSH.

Until I learned more of the details, I found it really confusing! once you can imagine how it all fits together it and things interact with each-other, it's way easier to remember.

Menstrual Cycle

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