Reproductive System Flashcards
(64 cards)
What happens in the hypothalamus in the reproductive system?
GnRH from the hypothalamus causes the release of follicle stimulating hormone (FSH) and luteinising hormone (LH) from the anterior pituitary
What do FSH and LH do at the gonads?
They act together to effect:
- Gametogenesis: sperm production in the testes and follicle development around ova in the ovary
- Steroidogenesis: hormone production; male - testosterone and inhibin, female - estrogen, progesterone and testosterone
Where does sperm mature?
In the epididymis
Where does sperm production take place?
In seminiferous tubules
What cells does FSH act on in the male reproductive system?
On the sertoli cells which drives the production of inhibin which inhibits the production of FSH from the anterior pituitary gland.
Sertoli cells are also known as support cells for spermatogenesis
What cells does LH act on in the male reproductive system?
On the leydig cells which drives the production of testosterone
What is the seminal fluid?
- Makes sperm motile
- Provide nutrients for sperm motility
- Neutralise acidic environment (urethra and vagina)
What is the prostatic fluid?
- Neutralise acidic environment
- Antibiotic
What is the bulbo-urethral glands?
- Mucus to neutralise acidic environment
- lubrication of penis tip
What are androgens?
Sex hormones that bring on puberty
Is testosterone lipid or water soluble?
Testosterone is a lipid soluble hormone. Which means that it travels bound and drives gene transcription.
What 3 developmental time points elevate testosterone levels?
- During development
- Following birth there is another peak
- Puberty
What is senescence?
Progressive loss of testosterone over time - but despite the loss of testosterone, males can still produce sperm throughout their lifetime
How long does the ovarian cycle go for?
~28 days
How many follicles does a female have?
2 million follicles waiting to mature and thats all you ever have. They die throughout the lifespan (limited number of ova in the female ovary)
What drives the development of follicles into different stages?
Once a female goes through pubertal onset, they develop more layers of cells around the egg.
What are granulosa cells and where are they located?
FSH stimulates granulosa cells which stimulates the growth of follicles.
Granulosa cells are closer to the egg.
Granulosa cells produce inhibin and estrogen
What are theca cells and where are they located?
LH stimulates theca cells which stimulates the production of androgens like production of estrogen.
Theca cells sit around the outside of the egg.
Theca cells produce testosterone
What hormones does the corpus luteum produce?
Produces large amounts of progesterone and estrogen
What happens in the follicular phase of the ovarian cycle?
Day 1-14
Maturation of a primary follicle to secondary follicle due to the influence of FSH. Only one follicle will mature and progress through to ovulation. As the follicle develops, it secretes estrogen, which stimulates the thickening of the uterus lining
What happens during ovulation?
Around day 14
Ovulation is triggered by a spike in LH. The mature follicle ruptures, releasing the follicle into the fallopian tube, ready for fertilisation
What happens in the luteal phase?
Day 15-28
After ovulation, the empty follicle transforms into the corpus luteum, which secretes progesterone and some estrogen. If the oocyte is not fertilised, the corpus luteum degenerates, hormone levels drop and the endometrium lining of the uterus sheds off, causing menstruation. If fertilisation does occur, the ova gets buried in the endometrium.
At what phases is there negative and positive feedback occurring from estrogen?
Follicular phase - negative feedback
Ovulation - positive feedback
Luteal Phase - negative feedback
How does estrogen provide negative and positive feedback?
Estrogen switches from negative to positive feedback at the level of the brain and the pituitary gland. Positive feedback means that instead of inhibiting the release of GnRH, it increases it which causes a huge increase in LH, known as the LH surge, which is critical for ovulation. The follicle then remodels into the corpus luteum which produces progesterone and estrogen and that returns to providing negative feedback to the brain.