Reproductive Hormones Flashcards
Hypothalamus
Gonadotrophin-releasing hormone
Pineal Gland
Melatonin
Anterior Pituitary
Luteinizing Hormone and Follicle-stimulating Hormone
Posterior Pituitary
Oxytocin
Gonads
Estrogens, progesterone, testosterone, inhibin, peptide hormones, prostaglandins, and activin
What are the gonadotrophins
FSH and LH
Moderation of reproduction through Estradiol Secretion
Estradiol has a biphasic effect on gonadotrophin secretion.
GNRH Secretion
Pulsatile manner. 7 min half-life. Binds to GnRH receptor on gonadotroph cells in the anterior pituitary..
Early Follicular phase moderation of reproduction via estradiol
Estradiol (moderate levels), has a NEGATIVE FEEDBACK.
Follicular phase moderation of reproduction via estradiol
Increased estradiol has POSITIVE FEEDBACK on the secretion of gonadotrophins (mostly LH) which triggers ovulation.
Continuous GnRH secretion
Lowers the secretion of gonadotropin hormones due to receptor desensitization
Which hormones are glycoproteins
LH and FSH
Composition of the gonadotrophins
2 non-identical alpha and beta subunits
Alpha subunit
Common to LH and FSH
What is a dimer
Combination of alpha and beta subunits
Half-life of FSH and LH
FHS has a longer half-life than LH
Beta subunit
Biological specificity
Luteinizing hormone stats
Regulated by the GnRH and gonadal steroids. Half-life of 30 minutes. Composed of alpha and beta subunits
Pulsation of LH
Stimulated by the pulse of GnRH. Increased estrogen leads to the peak of LH which trigger ovulation. Frequency of LH reduces near the end of the luteal phase.
What does LH stimulate
With FHS it stimulated estradiol synthesis and ovulation, formation of the corpus luteum, and progesterone secretion in the female. Stimulates secretion of testosterone by Leydig cells in the testes.
Follicle-stimulating Hormone stats
Composed of alpha and beta subunits. Half-life of 3-4 hours. Regulated by GnRH, steroids, inhibin and activin
What does FSH stimulate in the female
Growth and development of the follicle, ova production, and secretion of estradiol by granulosa cells