4D: hormonal control of growth Flashcards
andrew beard (22 cards)
in which pituitary gland is oxytocin produced?
posterior pituitary
in which pituitary are LH and FSH produced?
anterior pituitary
what is the function of FSH?
follicle stimulating hormone
- females: initiates development of oocytes and induces ovarian secretion of oestrogens
- males: stimulates sperm
and testosterone production
what is the hypothalamic hormone associated with FSH?
GnRH (gonadotropin releasing hormone) promotes secretion
what is the function of LH?
luteinising hormone
- females: stimulates secretion of oestrogens + progesterone, ovulation and formation of the corpus luteum
- males: stimulates sperm
and testosterone production
what is the hypothalamic hormone associated w LH?
GnRH promotes secretion
what does the steroid oestradiol/oestrogen (E2) induce? where?
from ovary
- sexual behaviour
- reproductive tract development
- controls gonadotrophin secretion
-> FSH and LH secretion
what does the steroid progesterone (P4) induce? where?
from ovary n placenta
- reproductive tract development
- maintains pregnancy
- controls gonadotrophin secretion
how does the hypothalamic-pituitary-ovarian axis work?
- hypothalamus secretes GnRH
- this induces pituitary to produce LH and FSH
- these induce ovary to produce P4 (progesterone) from the corpus luteus and E2 (oestradiol/oestrogen) from the follicles
what does the testosterone steroid induce? where?
from testes
- reproductive tract development
- sperm production
- sexual behaviour
- control of gonadotrophin secretion
how does the hypothalamic-pituitary-testes axis work?
- hypothalamus produces GnRH
- this induces pituitary to secrete LH and FSH
- these induce testosterone production in the testes from leydig and sertoli cells
what is an oestrous period?
the time during which a female is receptive to mating w a male
what is the time betw 2 oestrous periods called?
oestrous cycle
how does negative feed back work in males? (test. and GnRH)
- GnRH releases LH, which testosterone production in testis (leydig cells)
- testosterone inhibits hypothalamus from producing more GnRH
how does negative feedback work in females? progesterone and GnRH
- hypothalamus secretes GnRH
- GnRH releases LH, which induces ovaries (corpus luteus) to produce P4
- P4 inhibits GnRH secretion
how does positive feedback work in females? e2 and GnRH
only when P4 is low
- hypothalamus produces GnRH
- GnRH releases LH, which induces ovary (follicle) to produce oestrogen
- E2 induces hypothalamus to produce more GnRH
how does luteinising hormone rise and fall in the oestrous cycle?
spike of LH on first day of oestrous cycle following a significant drop until next cycle
how does oestrogen rise and fall during the oestrous cycle?
remains relatively steady throughout, with small increases after days 7 and 15, spike nearing end of cycle
how does progesterone rise and fall during the oestrous cycle?
starts off low, gradually builds, reaches peak at day 15, crashes until it reaches same low on day 21/0
how do seasonal polyoestrous animals detect their breeding seasons?
- melatonin is secreted from pineal gland during darkness
- pattern is detected -> long daylight/short daylight
- LH pulses to produce hormones
how can anovulatory ewes be stimulated to ovulate?
by introduction of rams
