Reproductive
Name 2 changes that occur in the ovaries as a result of rising FSH levels
1. follicular development 2. estrogen is produced by follicle
what is the Secretory stage?
15 - 28 day: endometrium increases in size and readies for implantation; stimulated by progesterone from the corpus luteum
what is the Proliferative stage?
6 - 14 day: regeneration of functional layer; stimulated by estrogen; at day 14, LH increases and ovulation occurs
what happens when there is fertilization?
Embryo produces LH-like hCG; PG maintains endometrium
which hormones are released from the pituitary gland at the beginning of the cycle?
Follicle stimulating hormone and Luteinizing hormone
what happens when there is no fertilization?
LH declines; PG declines; endometriuim breaks up
what triggers ovulation?
LH increases rapidly
why is this cycle an important adaptation for reproduction in humans?
This communication between the pituitary, ovaries,and uterus helps to synchronize the release of the egg with the optimum preperation of the uterus. Hormones in the cycle insure that the egg is only released when the uterus is in the final stages of preperation. this way, if the egg is fertilized, the uterus will be at its thickest when the embryo arrives.
when does ovulation usually occur?
between the proliferative & secretory stage around 14 days after the start of menses.
ovulation occurs where?
between the two phases
what does estrogen do to the lining of the uterus?
causes the lining to become thicker
what happens to the corpus luteum after the egg has been fertilized?
The corpus luteum continues to secrete progesterone to keep the uterus lining think and provide a good area for a zygote to develop. this lasts for the first 3 months of pregnancy.
what happens to the corpus luteum if the egg is not fertilized?
degeneration after 14 days
Oocytes mature where?
developing ovarian follicles
when in the cycle would progesterone levels be highest?
during the luteal phase which begins after ovulation
what hormones are secreted by the corpus luteum?
estrogen and progesterone
what is Menses & how long is it?
functional layer of the endometrium is sloughed; about 5 days
what signal later causes a rapid rise in the levels of FSH and LH?
high estrogen levels
The ovarian cycle has what 2 phases?
The follicular phase & the luteal phase
what does the hormone progesterone do the lining of the uterus?
increases endometrium size and prepares it for implantation
after ovulation what happens to the ruptured follicle?
it becomes the corpus luteum
what triggers the start of menstruation if the egg is not fertilized?
low levels of estrogen & progesterone from the breakdown of the corpus luteum causes menstruation to begin
what causes the change?
luteinizing hormone
what would you predict about the levels of progesterone in a pregnant woman?
the levels would be high
where is testosterone produced?
the leydig cells (interstitial cells)
On what organ does FSH act?
the ovaries
what signal in the blood reduces the production of FSH by the pituitary and limits the production of LH?
when the estrogen is low to moderate