Gonads 2 Flashcards
What are the fates of testosterone and where do they occur?
Reduction to DHT - male type phenotypic features
- Prostate
- Testes - seminif
- Seminal vesicles
- Skin - facial hair
- Brain
- Adenohypophysis
Aromatisation to Oestrogen
- Adrenals
- Testes - Sertoli
- Liver
- Skin - moobs
HOw is testosterone transported?
Blood
SHBG 68
Albumin 30
Free 2
In seminiferous
- androgen BG
What are the actions of androgens?
Fetus
Development of male internal and external genitalia
Fetal growth
HCG acts as LH and stims test
Adult - Spermatogenesis - Growth and development of male genitalia and secondary sex characteristics - Sex behaviour - Pubertal growth spurt Androgenic effects mediated by oestrogen
Define ‘oestrogen’
Substance that induces mitosis in the endometrium
Eg
17b oestradiol
Oestrone
What are the effects of oestrogens?
Stimulates proliferation Triggers LH surge for ovulation Feedback on GnRH -/+ Osteoblast stimualtion Metabolic actions Behavioural effects
Salt and water reabsorption Plasma protein synth Vaginal secretions Breast Skin
What are progestogens?
Any substance that induces secretory changes in endometrium
progesterone
What are the effects of progestogens?
Stimualtes secretory activity in cervix
Neg feedback on GnRH
Increase body temp
Decrease NaCl uptake
Stimualte alveolar growth in breast
What is the HPT axis?
Hypothalamus releases pulses of GnRH
LH and FSH in the adenohypophysis stim to release
Act on the testis
Specifically
- LH on the Leydig
- FSH on the Sertoli
Leydig produce testosterone
Sertoli - direct spermatogenesis
Inhibited (in)directly by testosterone and inhibin
What is the HPO axis?
Hypothalamus releases pulses of GnRH
LH and FSH in the adenohypophysis stim to release
Then ovary stim to release oestradiol, feeding back on inhibitory
ALSO INHIBIN
Describe both the hormone and follicular changes during the early follicular phase
Follicles starting to grow, but due to small size they only produce little amounts of oestradiol, thus poorly inhibiting FSH and LH.
Thus, these massively increase and lead to increased follicular growth
Describe both the hormone and follicular changes during the early-mid follicular phase
All the same but now oestradiol increasing due to the stimulation of growth and oestrogen release of one follicle by FSH and LH.
This is facilitated by a positive feedback loop
- as it grows there are more granulosa cells, which secrete more oestradiol, which lead to more growth etc
Describe both the hormone and follicular changes during the midfollicular phase
now oestradiol is starving FSH and LH - inhibit
This then kills off all the other follicles bar the Graafian.
Describe both the hormone and follicular changes during the late-follicular phase
Keeps growing
Certain point of oestrogen concentration triggers positive feedback in pituitary, leading to massive rise in LH
Describe both the hormone and follicular changes during the luteal phase
Progesterone after egg hatching
- formed by corpus luteum
If no fertilisation, oestradiol, progesterone and inhibin inhibit FSH and LH and crash the whole thing, leading to period.
Whata re the 5 phases
Early Early mid Mid Late Luteal
