Reproductive Endocrinology 9/8/15 Flashcards
What structures secrete sex steroids?
Adrenal cortex, the placenta, and the gonads.
What are the 3 major classes of sex steroids?
Pregnanes (21 C’s)
Androgens (19 C’s)
Estrongens (18 C’s)
The primary male hormone is _____ which is a ________.
Testosterone, androgen
The primary female hormones are ______ and _______.
Progesterone and Estradiol
______ can serve as a precursor for other steroids.
Progesterone
Synthesis and secretion of sex steroids are controlled by what?
The neuroendocrine system, HPG axis = hypothalamus, Ant. pituitary gland and gonads.
*Cannot be stored in vesicles b/c they are lipophilic!
Describe the secretion of GnRH….
Secreted from the hypothalamus
- Pulsatile secretion due to pacemaker neurons that produce AP’s.
Describe the secretion of LH and FSH…..
Secreted from the Ant. Pituitary gland.
- Pulsatile secretion in response to burst of GnRH from the hypothalamus.
Secretion of LH and FSH stimulates __________.
pulsatile secretion of gonadal steroids
What does continuous, non pulsatile GnRH secretion do?
Down regulates GnRH receptors in the Ant. Pituitary and inhibits LH and FSH secretion.
What do gonadal steroids regulate?
- Gametogenesis
- Hormone synthesis
- Regulate protein synthesis in other reproductive organs
What are the 3 types of cells in the testis with important reproductive functions?
- Spermatic cells
- Leydig cells or interstitial cells
- Sertoli cells
What do sertoli cells do? (3 things)
- Regulate spermatogenesis and produce hormone Inhibin in response to FSH.
- Inhbin has negative feedback actions on FSH secretion.
- produce androgen binding protein that helps sequester T in the testis
- Secretes tubular fluid to provide nutrients form spermatozoa.
What do Leydig cells do?
- Synthesize T in response to LH.
What do Spermatic cells do?
They are mitotically native spermatogonia and spermatocytes that mode through the walls of the seminiferous tables from the basal lamina towards the apical surface/lumen as they mature.
In the periphery, T is often converted to __________ by _______.
DHT by 5alpha-reductase
*DHT is potent androgen
_____ can be used to treat hair loss.
5-alpha reductase inhibitors!
*DHT promotes male pattern hair loss.
_____ Inactivates hair follicles.
DHT