Contol Of Repro Flashcards
What type of hormones does the anterior pituitary release?
Mostly trophic ie cause other hormones to be released
What type of gland is the anterior pituitary?
Endocrine
What type of gland is the posterior pituitary?
Neurosecretory gland
What are the types of hormones and the actual hormones produced by the anterior pituitary?
Glycoprotein hormones
- FSH
- LH
- TSH
Polypeptide hormones
- growth hormone
- ACTH
- prolactin
What are the different cells that produce the different hormones in the anterior pituitary?
Gonadotrophs - LH and FSH Thyrotrophs - TSH Somatotrophs - growth hormone Corticotrophs - ACTH Lactotrophs- prolactin
What are all of the hormones produced by the anterior pituitary involved in?
Reproduction
What hormones does the posterior pituitary produce?
ADH
Oxytocin
What is anterior pituitary secretion controlled by in general?
Hypothalamus via releasing hormones travelling in hypophyseal portal circulation.
How are the releasing hormones secreted?
Neurosecreted
Which hormone causes the rerelease of FSH and LH
Gonadotrophin releasing hormone (GnRH)
Release is pulsatile - once per hour
Actions of FSH and LH?
Control gamete production
Stimulate secretion of gonadal steroids
How is GnRH secretion controlled?
Other neurones -environmental effects -body weight Feedback from gonads - gonadal steroids -testosterone -oestrogen -progesterone
What effect does oestrogen have on the release of GnRH?
Moderate oestrogen reduces it by negative feedback
High oestrogen promotes GnRH by positive feedback
Reduces amount of GnRH secreted per pulse
What effect does progesterone have on GnRH secretion?
Progesterone increases the inhibitory effects of moderate oestrogen, preventing the positive feedback from high oestrogen so no LH surge
Also reduces frequency of pulses
What effect do testosterone and oestrogen have on LH and FSH?
Testosterone reduces their secretion
Oestrogen at moderate conc reduces their secretion
At high conc increases their secretion
What is the effect of inhibin on LH and FSH release?
Released from gonad
Reduces FSH secretion selectively
Does not affect LH
What does FSH bind to in males?
Sertoli cells
What does LH bind to in males and what is its effect?
Leydig cells
They secrete testosterone
Promotes spermatogenesis
Maintains the reproductive system
What is the rate of inhibin secretion related to? Effects?
The rate of spermatogenesis
If it speeds up, more inhibin released
Reduces FSH secretion
Rate of spermatogenesis back to normal
When is testosterone at its highest?
In the morning
