Hormonal Control In The Menstrual Cycle Flashcards
How many hormones are involved in the menstrual cycle?
Four
Describe how the hormones work together in the menstrual cycle
(2)
Each hormone causes the production of the hormone following it
Each hormone inhibits the preceding hormone
Name the four hormones of the menstrual cycle.
Follicle-stimulating hormone (FSH)
Oestrogen
Luteinising hormone (LH)
Progesterone
What does FSH stand for?
Follicle-stimulating hormone
What does LH stand for?
Luteinising hormone
What is the site of production of FSH?
Produced by the pituitary gland
What is the time of production of FSH in the menstrual cycle?
It is produced early in the cycle (days 1 to 5)
What hormones used in the menstrual cycle come from the pituitary gland?
(2)
FSH
LH
What hormone is produced from days 1-5?
FSH
What is the function of FSH in the menstrual cycle?
It stimulates a few potential eggs to develop, surrounded by Graafian follicles
FSH stimulates a few eggs to develop surrounded by Graafian follicles, how many of these usually survive?
Only one follicle (and egg) normally survives
FSH sometimes used in fertility treatments?
Because it stimulates the ovaries to produce eggs
What can sometimes happen during fertility treatments if FSH is used to stimulate the ovaried to produce eggs?
Often a number of eggs develop, resulting in multiple births
What is secreted by the Graafian follicle?
Oestrogen
Why can FSH be said to cause the production of oestrogen?
As FSH stimulate the production of eggs which are surrounded by Graafian follicles which secrete oestrogen
What is the site of production of oestrogen?
It is produced by the Graafian follicle (in the ovary)
What is the time of production of oestrogen in the menstrual cycle?
From days 5 to 14 (mainly)
What hormone is produced from days 5 to 14?
Oestrogen
What is the function of oestrogen?
2
It causes the endometrium to develop
It also inhibits FSH by negative feedback which ensures no further eggs develop
How does oestrogen inhibit FSH?
By negative feedback
Why is oestrogen used in the contraceptive pill?
Because it inhibits FSH be negative feedback which ensures no further eggs develop
When is oestrogen production at its highest?
Just before day 14
Levels of oestrogen are high just before day 14, what does this do?
It stimulates the release of LH
What stimulates the release of LH?
High levels of oestrogen just before day 14
What is the site of production of Luteinising hormone?
Pituitary gland
What is the time of production of luteinising hormone in the menstrual cycle?
Day 14
What is the function of luteinising hormone?
2
It causes ovulation
It then causes the remains of the Graafian follicle to develop into the corpus luteum
What hormone is produced on day 14?
Luteinising hormone
What does luteinising hormone cause the remains of the Graafian follicle to turn into?
The corpus luteum
What does luteinising hormone cause to turn into the corpus luteum?
The remains of the corpus luteum after ovulation
What does the corpus luteum make?
Progesterone
What is the site of production of progesterone?
Corpus luteum (in the ovary)
What is the time of production of progesterone in the menstrual cycle?
Produced from days 14 to 28
What is the function of progesterone?
4
It maintains the structure of the endometrium
It inhibits by negative feedback the production of FSH which prevents further eggs from developing
It inhibits LH so that further ovulation and pregnancies are prevented
It prevents contractions of the uterus
What does progesterone inhibit?
2
It inhibits by negative feedback the production of FSH which prevents further eggs from developing
It inhibits LH so that further ovulation and pregnancies are prevented
What does progesterone prevent from happening?
It prevents contractions of the uterus
What happens to the corpus luteum if pregnancy does not occur?
The corpus luteum will start to degenerate around day 22
On what day will the corpus luteum start to degenerate if pregnancy does not occur?
Day 22
What will happen on day 22 if pregnancy does not occur?
The corpus luteum will begin to degenerate
What happens on day 28 if pregnancy does not occur?
5
Low levels of progesterone and oestrogen produce the following effects:
FSH secretion by the pituitary gland is not longer inhibited
As the FSH level rises new eggs begin to develop
The uterus contracts and the endometrium is shed from the body
Menstruation and a new cycle have begun
What effects are brought on by low levels of progesterone and oestrogen?
(4)
FSH secretion by the pituitary gland is not longer inhibited
As the FSH level rises new eggs begin to develop
The uterus contracts and the endometrium is shed from the body
Menstruation and a new cycle have begun
What causes menstruation?
Low levels of both progesterone and oestrogen which causes the uterus to contract
