Reproductive Hormones, Menstrual & Ovarian Cycles Flashcards
What are hormones?
- chemical messengers
- diffuse from endocrine system
- carried in blood to target tissues and organs
- influence cell growth and metabolism
What are gonadotrophin released hormones?
LH and FSH
What’s the main difference between secretion of male and female reproductive hormones?
- males are continuously fertile from puberty to old age. There hormones are secreted at a steady pace.
- female hormones are only are secreted cyclically and female are therefore only futile a few days eat month
What secretes LH and FSH in both sex?
GnRH (Gonadotrophin-releasing hormone) from the hypothalamus stimulates secretion of the two gonadotrophin hormones - LH and FSH - from anterior pituitary gland, which acts on the sexual hormones
Name the 5 male reproductive hormones
- GnRH
- LH
- FSH
- Testosterone
- Inhibin
Where is GnRH produced and what does it do in males?
- hypothalamus
- controls pituitary secretions
Where is LH (luteinising hormone) produced and what does it do in males?
- anterior pituitary gland
- stimulate the leydig cells to secrete testosterone
Where is FSH (follicle-stimulating hormone) produced and what does it do in males?
- anterior pituitary gland
- acts on sertoli cells to stimulate spermatogenesis and secretion of the hormone inhibit to inhibit FSH secretion
Where is testosterone produced and what does it do?
- produced by interstitial cells of leydig cells in testes
- influences spermatogenesis
- responsible for changes in puberty
- promotes sex drive
- inhibits released of GnRH, LH, FSH in negative feedback loop
Where is inhibin produced and what does it do?
- produced by sertoli cells in testes
- inhibits GnRH and FSH secretions when sperm count is too high
- negative feedback
Name the 5 female reproductive hormones
- GnRH
- LH
- FSH
- Progesterone
- Oestrogen
Where is GnRH produced and what does it do in females?
- hypothalamus, when there are low levels of ovarian hormones
- controls secretions of LH and FSH
Where is LH produced and what does it do in females?
- anterior pituitary gland
- stimulates development of oocyte and follicle
- stimulates ovulation
- increased progesterone
- aids development of corpus luteum
Where FSH produced and what does it do in females?
- anterior pituitary gland
- causes immature oocyte and follicle to develop
- increases oestrogen secretion
- stimulates new gamete formation
- stimulates development of uterine wall after menstruation
Where is progesterone produced and what does it do?
- by corpus luteum, following ovulation
- stimulates thickening of uterine wall during pregnancy
- involved in preparing breast tissue in pregnancy
- relaxes smooth muscle
- prevents contractions
Where is oestrogen produced and what does it do?
- graafian follicles, corpus luteum and placenta (wks 6-7)
- stimulates thickening of uterine wall for implantation and fertilisation
- stimulates maturation the oocyte
- stimulates development of sex characteristics
- prepares breast for lactation
- inhibits FSH
- increases LH
What is oogenesis?
the formation of oogonia in the ovaries occurs during fetal life
Name the 3 phases of the ovarian cycle?
follicular, ovulation, luteal
What is the ovarian cycle?
the physiological changes that occur in the ovaries, essential for the preparation and release of the oocyte.
What happens during the follicular phases?
- folliculogenesis occurs stimulated by LH and FSH
- dominant follicle secretes inhibin which suppresses FSH
- dominant follicle forms a bulge near surface of ovary and ovulation occurs within about 1 week
What happens during ovulation phase?
- high oestrogen levels cause surge in LH
- oocyte matures, follicle wall weakens, ov occurs day 14
- graafian follicle rupture, releases secondary oocyte
- fimbraie guide oocyte to uterus
- oocyte divides to become haploid
- ov cramps
- music thickens, viscosity increases
What happens during luteal phase?
- corpus luteum formed from ruptured follicle
- hormone production to develop endometrium and uterus
- increased uterine contractility
- cervical mucous thick and sticky
- if no fertilisation, hormone levels decrease and cycle begins again
- corpus luteum becomes corpus albicans
What is the menstrual cycle?
the physiological changes occurring in the endometrium in order too receive the fertilised egg
What are the 3 phases of the menstrual cycle?
menstrual, proliferative, secretory
