LC 2.11 Flashcards
1
Q
types of androgens
A
- testosterone
- androsterone
- androstenediol
- androstenedione
- dihydrotestosterone
- dehydroepiandrosterone
- testosterone is lipophilic and largely bound to serum binding proteins
2
Q
where do androgens go?
A
- testosterone diffuses to the sertoli cells
- testosterone can go to peripheral tissues for conversion to oestrogen
- testosterone can go to peripheral tissues for conversion to DHT
- testosterone can go to target tissues
3
Q
what does 5 alpha reductase do?
A
convert testosterone to dihydrotestosterone
4
Q
what does sertoli cells do?
A
- produce ABP which keep high level of testosterone
- this is necessary for successful spermatogenesis
5
Q
what is the steroidogenic pathway?
A
- LH in the blood stimulates the production of androstenedione from cholesterol in leydig cells of the testes
- androstenedione is converted to estrone and secreted into the blood as oestrogen
- androstenedione is converted to testosterone and secreted into the blood and lymph
6
Q
what is the endocrine regulation of testicular function?
A
- regulation of hypothalamic-ituitary testis axis in continous levels of ABP and testosterone
- testosterone stimulates secondary sex organs and libido
- testosterone and ABP stimulate spermatogenesis
7
Q
describe the hypothalamic-pituitary-testis axis
A
- hypothalamus secrete GnRH
- GnRH travels downt eh anterior portion of teh pituitary by the hypophyseal portal system and stimulate the secretion of Lh and FSH
- FSH cause sertoli cells to be stimulate production of inhibin B
- LH will cause leydig cells to produce testosterone
- inhibin B has negative feedback on teh anterior pituitary and hypothalamus
testosterone has negative feedback on the anterior pituitary and hypothalamus
8
Q
what is inhibin B
A
- protein not hormone
- only in males
- inhibits FSH production
- serum marker of testicular activity
- may have tumour suppressor activity
