Flashcards in Reproductive System Deck (162)
sperm production facts
- 300 million per day
- constant fertility post puberty, gradual decline with age
- 1500 sperm/second
oocyte production facts
- 7 million follicles at birth
- 400 ovulate
- 0 follicles at menopause
relative size of egg and sperm
sperm is the smallest cell in the body, whereas egg is the largest
hierarchal arrangement of the neurons between the pituitary and the hypothalamus allows for...
function of the gonads (ovaries, testes)
1. produce gametes
2. produce reproductive hormones
the hypothalamus sends ____________ neurons to the posterior pituitary, where it releases _________ which is made in the __________ and affects ________ organs.
___________ neurons within the hypothalamus release ______ into _______ vessels which lead into the anterior pituitary, stimulating the release of __________ (___ and __). These hormones stimulate ___________ in males and ___________ in females.
the hypothalamus sends _neurosecretory_ neurons to the posterior pituitary, where it releases _oxytocin_ which is made in the _hypothalamus_ and affects _target_ organs.
_Neuroscretory_ neurons within the hypothalamus release _GnRH_ into _portal_ vessels which lead into the anterior pituitary, stimulating the release of _gonadotrophins_ (_LH_ and _FSH_). These hormones stimulate _spermatogenesis_ in males and _oogenesis_ in females.
4 water soluble, peptide and protein, reproductive hormones and their sites of secretion
1. GnRH - gonadotrophin releasing hormone, which is released from the hypothalamus
2. FSH - follicle-stimulating hormone, which is released from the anterior pituitary
3. LH - Luteinising hormone, which is released from the anterior pituitary
4. Oxytocin, which is made in the hypothalamus but released at the posterior pituitary
3 lipid soluble, steroid reproductive hormones and their sites of secretion
1. androgens, which are released from the testes
2. Oestrogens, which are released from the ovaries
3. progestagens, which are released from the ovaries
how are lipid soluble hormones transported?
steroid hormones made from?
2 androgens and their differences
2. 5α dihydrotestosterone (more active)
3 oestrogens and their differences
2. oestrone (weaker)
oestradiol is active during which stage of a girls life? (how does it compare to oestrone)
puberty through to menopause.
Oestradiol is a weaker oestrogen
produced by the placenta
softens the cervix to prepare for birth
PROGESTERONE (menstrual cycle and pregnancy)
Neurosecretory cells of the posterior pituitary
1. hormones synthesised in the hypothalamus
2. carried down the axon
3. stored in secretory vesicles in the posterior pituitary
4. nerve impulse leads to exocytosis
5. OXYTOCIN or ADH released into the blood from the posterior pituitary
effects of oxytocin
- smooth muscle contraction
- milk ejection
- contraction of the uterus during childbirth (used to induce labour)
water retention in the kidneys
neurosecretory cells involved with the anterior pituitary
- Don't leave the hypothalamus, release hormones (GnRH) into hypophyseal portal vessels
- Hormones act on the gonadotrophs of the anterior pituitary to release FSH and LH
somatotrophs, lactotrophs, thyrotrophs, and corticotrophs are all...
why does the hypothalamus release GnRH into hypophyseal portal vessels?
if it was diluted in the blood stream it wouldn't be effective
can conduct a nerve impulse, synthesis and carry and release neurosecretory hormones
"the reproductive system only has single positive hormone"
how do hypothalamic secretions release?
secretions occur in discrete bursts, separated by periods of little or no secretion.
Prevents desensitisation and down-regulation
LH effect on Males vs. females
Male: stimulates production of testosterone
Female: secretion of female sex hormones and stimulate ovulation
FSH effect on Males vs. females
Male: growth of spermatozoan
Female: growth of ovarian follicles
negative feedback effect of sex hormones
inhibit hypothalamus from releasing GnRH and inhibit Anterior pituitary from releasing FSH and LH
females produce no androgens and Males produce no oestrogens
false. they produce some
key properties of androgens in males
- Male sex development
- sexual behaviour
- muscle development