Reproductive system Flashcards
Describe the maturation of follicles in the ovary
Ovary has primordial follicles in medulla.
Each follicle has a primary oocyte, surrounded by follicular cells.
These turn into granulosa cells at puberty.
Follicles turn into graafian follicles. Antrum forms.
Has theca cells which produce andostenedione, and the granulosa cells use aromatase to convert this into estradiol.
Describe a normal menstrual cycle
Starts on the first day of bleeding
Lasts 28 days
Follicular phase = 14 days
Ovulation occurs on day 14
Luteal phase = 14 days
How is the menstrual cycle controlled?
Controlled by hypothalamus, which releases GnRH which makes the pituitary release LH + FSH.
LH stimulates the theca cells - making progesterone
FSH stimulates the granulosa cells - making oestrogen
Oestrogen + progesterone act as negative feedback to pituitary
Follicular phase
Graafian follicles grow due to FSH - this increases oestrogen.
This acts as neg feedback, so reduced FSH.
Then more oestrogen to release more FSH (turns into positive feedback)
Luteal phase
After ovulation, remains of follicle turn into corpus luteum.
Granulosa cells produce inhibin which inhibits production of FSH, reducing levels.
Oestrogen levels fall without FSH.
Theca cells produce more progesterone, becoming dominant hormone.
If fertilisation occurs, progesterone continues to be produced.
If not, it stops.
Endometrial changes during menstruation
Thickens during follicular phase
Spiral arteries are formed in luteal phase
When is the proliferative phase + what occurs?
Days 5-14
Immediately after menstrual phase
Increased oestrogen to grow + repair the endometrium
What hormone does the corpus luteum produce?
Progesterone
When does the LH surge occur + why?
Days 11-13
High levels of oestrogen = high level of LH
Causes membrane of Graafian follicle to thin + rupture
What is the function of progesterone?
Stimulation of oestrogen production
Initiation of secretory phase of endometrium
Increase in basal body temp
Inhibition of LH + FSH production
When is the most fertile period for women?
Days 9-16 (5 days before ovulation + 1-2 days after)
Where is GnRH produced?
Hypothalamus
What is the function of LH?
Formation + maintenance of corpus luteum
Thinning of graafian follicle
What is the secretory phase + when is it?
Day 14-28
Ruptured graafian follicle develops into corpus luteum
Produces progesterone which induces secretion in the endometrium
Where are LH + FSH produced?
Anterior pituitary
