8 - Menstrual Cycle

How would levels of progesterone be in a pregnant woman?

They would be high.

Name two changes that occur in the ovaries as a result of the rising FSH levels.

- An egg in the follicle begins to mature - The follicle produces estrogen

When does ovulation usually occur?

14 days before the start of the next cycle.

On what organ does FSH act?

A follicle in one of the ovaries

What triggers ovulation?

A rapid rise in LH.

When in the cycle would progesterone levels be highest?

After ovulation. (luteal phase)

What hormones are secreted by the corpus luteum?

Estrogen & progesterone.

Which hormones are released from the pituitary gland at the beginning of the cycle?

FSH & LH

What happens to the corpus luteum if the egg has been fertilized?

HCG from the zygote signals the corpus luteum to continue functioning. It will last for the 1st 3 months of the pregnancy. After that, the placenta will continue to produce the estrogen & progesterone.

What signal later causes a rapid rise in levels of FSH & LH?

High levels of estrogen.

What event is used to mark the beginning of the menstrual cycle?

The start of menstruation

What signals in the blood reduces the production of FSH by the pituitary and limits the production of LH?

Increasing, but still relatively low amounts of estrogen.

What happens to the corpus luteum if the egg is not fertilized?

It breaks down after 14 days.

What does estrogen do to the lining of the uterus?

It causes the lining to thicken.

After ovulation, what happens to the ruptured follicle?

It is converted to a corpus luteum.

What causes this change? (change of ruptured follicle to corpus luteum)

Ovulation which is caused by a rapid rise in LH.

What triggers the start of menstruation if the egg is not fertilized?

The corpus luteum breaks down, causing levels of estrogen & progesterone to fall. The lower levels of these hormones trigger menstruation.