H-AP-Gonad axis Flashcards
outline the pathway of GnRH (male)
Hypothalamic hormone is GnRH
Anterior Pituitary Hormones are FSH and LH which act on the endocrine cells of the gonads
The endocrine cells of the gonads secrete androgen and targets germ cells of the gonads
what do the testes produce ?
They produce sperm (Sertoli cells) and testosterone (leydig cells)
where does testosterone act ?
Testosterone is secreted by the leydig cells located between seminiferous tubules.
fetal; masculinizes tract and external genitalia
Puberty & adulthood; -growth, maturation and maintenance of male reproductive system
- sex drive
- secondary sex characteristics (hair growth, voice, skin, body shape)
- bone, muscle
- brain (cognition, behaviour)
Why is there increased risk of inferticlity in males taking anabolic steroids?
AAS mimic the effects of testosterone
Excess testosterone shuts down pathway;
- testes stop producing sperm
- stop producing testosterone
- decrease libido and fertility
outline the pathway of GnRH (female)
Hypothalamic hormone is GnRH
Anterior Pituitary Hormones are FSH and LH which act on the endocrine cells of the gonads
The endocrine cells of the gonads secrete estrogen and progesterone and targets germ cells of the gonads
What is the cycle of hormones that the female reproductive physiology endures ?
Anterior pituitary hormones act on the ovaries
ovaries produce eggs
ovaries produce hormones that act on the uterus
uterus gets ready for pregnancy, then is stripped of lining if implantation doesnt occur
what is responsible for mentrual bleeding ?
Endometrial spiral arteries are responsible for mentrual bleeding
** animals that lack arteries do not bleed when they shed their endometrium
What is special about the female reproductive cycling of hormones?
Complex coupling of two cycles
- Ovarian cycle - regulated by FSH, LH
- Uterine (Mentrual) cycle - estrogen and progesterone
these occur simultaneously, coupled by GnRH from the Hypothalamus, and FSH/LH from the anterior pituitary
what occurs in stage 0 of female cycle ?
HPG - axis : Gonadotropin secretion from the anterior pituitary
Ovaries : FSH influences several ovarian follicles to being maturation
Uterus : Day 1 of menstrual bleeding begins
what occurs in stage 1 of female cycle ?
HPG-axis : early - estrogen inhibits GnRH, FSH, LH (prevents more follicles from same cycle)
Ovaries : FSH declining, LH increasing
Uterus : estrogen stimulates endometrial growth
what occurs of stage 2 of female cycle ?
Ovulation
Ovulation REQUIRES an LH surge, stimulated by estrogen
Mature follicle dissolves its matrix, ruptures
egg released
> what’s left forms the corpus luteum
What occurs in stage 3 of the female cycle ?
Early/Mid luteal phase
HPG-axis : - Corpus luteum produces progesterone, estrogen
- Negative feedback on HPG-axis (suppress gondaotropins)
Ovaries : Early - corpus luteum develops
Later - corpus luteum regresses
Uterus : Early - Endometrium anticipating pregnancy
Progesterone - cervical mucosal barrier thickens
what occurs in the stage 4 of the female cycle ?
Late luteal-menstruation
HPG-axis : estrogen, progesterone down - removes negative feedback on HPG : FSH & LH up
Ovaries : Corpus luteum lives 12 days then apoptosis
Uterus : Endometrium requires progesterone or else vasculature contracts and dies, sloughs off, menstruation starts (@14 days post ovulation)
What is the significance in the the raise in body temperature for women ?
Starting at 1 day after LH peak, basal body temperature sharply rises.
This is due to an increase in progesterone
why do women get PMS ?
- Decreased mood, anxiety, bloating, breast tenderness, weight gain, difficulty concentrating
> temporal correlation with luteal phase
> requires ovulation & formation of corpus luteum
> link with neorutransmitter actions with HPG hormones
