Hormones and the menstrual cycle
What is the corpus luteum?
a hormone-secreting structure that develops in an ovary after an ovum has been discharged but degenerates after a few days unless pregnancy has begun.
What causes ovulation?
a peak of LH hormone
What is progesterone?
a steroid hormone responsible for the decidualization of the endometrium (its development) and maintenance, respectively
The placenta takes over the role of the ____________ _____________.
corpus luteum
What is the follicle called once an egg is released?
corpus luteum
What is inside the ovaries?
hundreds of cells that could develop into mature eggs
What does this prevent form happening?
ovulation
What is this movement called?
ovulation
What is gestation?
the length of pregnancy
What happens whilst a follicle is growing?
the lining of the uterus has been thickens
What is menstruation?
the monthly bleeding where the lining of the uterus is shed
What does oestrogen do? (2 things)
1) Causes the lining of the uterus to build up. 2) Stimulates another hormone which leads the ovulation.
Which 4 hormones control the menstruation cycle?
1) Oestrogen 2) Progesterone 3) LH (Luteinising hormone) 4) FSH(Follicle Stimulating Hormone)
What happens if there is no fertilisation? (2 things)
1) The corpus luteum breaks down and stops making progesterone. 2) The lining of the uterus then passes out of the vagina
What are the four parts to the menstrual cycle?
1) menstruation 2) uterus lining builds up 3) ovulation 4) maintenance of uterus lining
What does progesterone do? (3 things)
1) signals the pituitary and hypothalamus glands in the brain to slow down the production of the hormones FSH and LH (which prevents additional follicles in the ovaries from developing and ovulating) 2) Maintains the lining of the uterus 3) Inhibits the release of further eggs (by stopping other hormones being produced)
What happens if pregnancy does not occur? (3 things)
1) the corpus luteum regresses (return to a less developed state) 2) the hormone levels of progesterone and estrogen go back down 3) the breakdown of the endometrium causes menstrual bleeding
What does progesterone prevent?(2 things)
1) the endometrium from being expelled 2) continues to prevent further ovulation
What are the two primary phases of the menstrual cycle?
1) the follicular phase 2) the luteal phase
how long will the corpus luteum last
10 to14 days and then die
How long does the average menstrual cycle last?
28 days
What happens in phase 4?
The wall is maintained for 14 days. If the egg is unfertilised then the lining breaks down and the cycle starts again.
What will the embryo start to form?
a very early placenta
Is progesterone most present before pr after ovulation?
after
What does FSH cause?
an egg to mature inside a follicle in the ovaries
Is oestrogen most present before pr after ovulation?
before
What does this hormone do? How?
completes the development of the uterine lining by thickening and maintaining it,
What is it essential for?
establishing and maintaining pregnancy in females
What many happen if sexual intercourse has taken place? Where?
fertilisation in the oviduct
If pregnancy does occur, what early pregnancy hormone will be released by the placenta?
hCG
Which hormone will a pregnancy test detect?
hCG
If you get pregnant, what is the first thing the embryo will do?
implants itself into the uterine lining
What is the endometrium?
inner lining of the uterus, richly supplied with blood vessels
What does the corpus luteum do if an egg is fertilised?
it carries on making progesterone
What happens to what is left over of the follicle?
it forms a structure in the ovary called the corpus luteum
What happens every month to one of these cells?
it grows inside a ball of cells called a follicle
What hormone makes this happen?
oestrogen
What is ovulation stimulated by?
oestrogen
What happens as a response to FSH?
oestrogen is secreted from the ovaries
What is LH hormone vital for?
ovulation and what happens just after ovulation.
What is the uterus?
part of the female reproductive system where the fertilised egg will implant
What does FSH stimulate the ovaries to do?
produce oestrogen
What does hCG signal the corpus luteum to continue secreting?
progesterone
What does the corpus luteum make?
progesterone
What is FSH also inhibited by?
progesterone
What is ovulation inhibited by?
progesterone
What does it secrete? and at what time in a pregnancy?
progesterone and oestrogen - during the early pregnancy
What does the corpus luteum release? Why?
progesterone to maintain the uterus lining
What will the placenta do later on in pregnancy?
secretes progesterone
The uterus lining will NOT ________ and menstruation will NOT ________________.
shed, happen
What happens to the endometrium if pregnancy DOESN'T occur?
sheds in a process known as menstruation
Define the menstrual phase
the 1st phase of the menstrual cycle when the menstruation occurs
Define the follicular phase
the 2nd phase of menstrual cycle where the uterine lining builds up and follicles ripen
Define the ovulation phase
the 3rd phase of the menstrual cycle when ovulation happens
Define the luteal phase
the 4th phase of the menstrual cycle where the uterus lining is maintained so that a fertilised egg can implant
What is implantation?
the attaching of the embryo to the wall of the uterus
What happens to the endometrium each month?
the endometrium thickens and renews itself, preparing for pregnancy
What happens to the folic in the middle of the menstrual cycle?
the follicle moves towards the edge of the ovary and the egg is released as the follicle bursts open
Which gland is this hormone secreted from?
the pituitary gland
What is oestrogen and progesterone produced by in the later stages of the pregnancy?
the placenta
What does this early placenta release?
the pregnancy hormone hCG
What is the menstrual cycle?
the regular natural change that occurs in the female reproductive system (specifically the uterus and ovaries) that makes pregnancy possible
What is ovulation?
the release of an egg from the ovary
What is an oviduct?
the tube linking the ovary with the uterus
What is the luteal phase?
this is post-ovulation when the body prepares the womb to accept a fertilized egg or embryo.
Why does the uterus form a lining?
to prepare for the fertilised egg to sink into it and develop into an embryo
Why does blood build up in the uterus?
to receive a fertilised egg (if there is one)
What is another job of oestrogen?
to slow down the production of FSH, while stimulating the secretion of LH
What is the follicular phase?
when a select number of follicles in the ovary mature until one releases an egg.
What happens in phase 1?
Menstruation Phase: The uterus lining breaks down for 4 days
Does the menstrual cycle have a beginning/ end?
No, the cycle is continuous, however the first day of menstruation is usually called day 1.
What happens in phase 3?
Ovulation: by this timea follicle has matured which releases an egg.
What happens in phase 2?
Phase 2: The uterus lining builds up again for 10 days.
What does oestrogen inhibit?
FSH
Which hormone causes this follicle to grow
FSH
What does progesterone inhibit the release of?
FSH and LH by the pituitary