hormones in menstrual cycle Flashcards
what are hormones?
Hormones are chemical messengers produced by endocrine glands. These chemicals are transported by the blood to their site of action and generally cause an effect over a long period of time.
what are the 4 hormones in the menstrual cycle?
folicle stimulating hormone FSH
leutinising hormone LH
oestrogen
progesterone
what does FSH do ?
Stimulates the maturation of a primary follicle.
Stimulates the ovary to secrete oestrogen.
what does oestrogen do?
Stimulates the anterior pituitary gland to secrete luteinising hormone.
Stimulates the uterus to produce a new endometrium.
Inhibits the secretion of FSH by the anterior pituitary gland.
what does leutinising hormone (LH) do?
Causes the Graafian follicle to release a secondary oocyte = ovulation.
Stimulates the formation of a corpus luteum from the Graafian follicle which then secretes progesterone.
Inhibits the secretion of oestrogen by the ovary.
what does progesterone do?
Maintains the endometrium in preparation for implantation of a blastocyst.
Stimulates the secretion of oestrogen.
Inhibits the secretion of FSH and LH.
what happens if implantation doesnt occur?
corpus luteum degenerates
progesterone levels decrease
endometrium breaks down
FSH secretion is no longer inhibited and the cycle begins again.
when there is more of a hormone does the effect increase or decrease?
Each of the four hormones has an increased effect as the concentration of that hormone increases.
what type of effect do the hormones have and is it negative or positive feedback
Most of them have a stimulatory effect and an inhibitory effect. In this way they operate a series of negative feedback loops that control the female reproductive cycle.
