Lecture 24 Flashcards
What are the two different types of hormones that are present in the male reproductive system?
- Gonadotropins (secreted from the anterior pituaritary)
- Steroids- (androgens- testosterone)
Why is the gonadotropin pulse centre important?
Pulsatile nature of the GnRH obligatory for most gonadotropin secretion, continuous exogenous GnRH suppresses LH and FSH activity.
What are the two main components of the testis?
- Seminiferous tubules- comprise approximately 90% of the mass (site of spermatogenesis)
- Amongst these are Leydig cells (site of testicular androgen production)
What is the main function of the Leydig cells?
They are the principle site of production and secretion of testosterone
What is the main function of the Sertoli cells?
- Restrict transport between the blood and the developing spermatogonia and hence control germ cell nutrient availability
- Androgen binding hormone and inhibin are both produced by the Sertoli cells
What are the main actions of testosterone?
- Enzyme called 5-Alpha-reductase converts testosterone to DHT (the active form)
- Muscles do not have this enzyme and hence respond to the enzyme directly
- DHT binds with a cytoplasmic receptor causing it to dimerise and react with DNA and then stimulate protein synthesis
Name a couple of ways that male fertility can be managed:
- Giving exogenous hormones
- Giving neurotransmitters
- Altering the day-length
- Changing the availability of pasture
What type of receptor do Leydig cell respond to?
LH receptors (has no FSH receptors on it’s surface)
How does testosterone control it’s own production?
has a negative feedback on GnRH and LH
What is the effect of FSH?
stimulates spermatogenesis
Describe the negative feedback effect of inhibin:
negative feedback on FSH specifically
