Important Hormones! Flashcards
All hormones required to know and little summaries of different things they do. Only the things I don't know, not the common knowledge things.
What are the three major hormone types?
Lipids, proteins, monoamines
What are steroids and eicosanoids?
Lipids
What are gonadotropic hormones?
Proteins
What are catecholamines?
Monoamines
3 oestrogen types?
Oestradiol, oestrone, oestriol
Where is LH, FSH and GH (growth hormone) released from?
Anterior Pituitary.
Where is oxytocin and ADH secreted from?
Posterior Pituitary.
How is the structure of oxytocin different to that of ADH?
Oxytocin has Isoleucine and Leucine.
ADH has Phenylalanine and Arganine.
What 3 major things is oxytocin important for?
smooth muscle contraction (milk ejection, birth)
Induce labour
Sexual attraction
What is another name for ADH?
Vasopressin
What is the main function of ADH?
Water retention and vasoconstriction.
What are four examples of glycoprotein hormones?
LH, FSH, TSH, hCG
What are the 5 different groups of anterior pituitary gland secretory cells?
Gonadotrophs (FSH, LH) Somatotrophs (GH) Thyrotrophs (TSH) Lactotrophs (Prolactin) Corticotrophs (ACTH)
What 3 hypothalamic hormones act on Prolactin, and what effect do they have?
Prolactin Releasing Hormone (PRH) stimulates release of prolactin.
TRH -> stimulates release
PIH -> INHIBITS release
How are pulses of GnRH regulated?
Oestradiol
Neural influence
endorphins
gonadotrophins (feedback)
Describe the structure of gonadotrophins.
Heterodimers
2 dissimilar subunits (a and B)
non-covalent interactions
In a single species, the a-subunit is common to all 4 hormones (LH, SH, TSH, hCG). There are 92aa residues.
The B-unit is what differs for each hormone.
LH - 114
FSH - 118
TSH - 113
hCG - 145
In males, where does testosterone and inhibin act (feedback)?
Testosterone = anterior pituitary + hypothalamus Inhibin = ONLY anterior pituitary.
In females, where does estradiol, inhibin and progesterone act (feedback)?
Estradiol = pituitary + hypothalamus Inhibin = ONLY pituitary Progesterone = ONLY hypothalamus
If you infuse GnRH over a long period, what happens?
LH and FSH are over secreted and desensitisation of receptors occurs.
Which hormone can diffuse through Sertoli cells?
Testosterone
In pre-pubertal testes, what is the role of hCG?
Acts like LH, increasing testicular blood flow (by decreasing vascular resistance).
If the hypothalamus is taken away, what is the effect of infusing GnRH?
It doesn’t restore secretion of LH and FSH.
What happens when the pituitary is removed from a male?
Decrease in testosterone and arrest in spermatogenesis.
What happens if testosterone replacement therapy is used in males?
Leydig cells still involute but spermatogenesis keeps occurring.
What hormone mediates the pituitary control of Leydig cells?
LH
If LH is given at time of pituitary removal, what happens?
No leydig involution
Testosterone maintained
Spermatogenesis continues
What happens when there is a delay in giving LH after hypophysectomy?
LH alone is not enough to restore spermatogenesis, thus FSH is also required. This stimulates the sertoli cells to activate androgen receptors. Androgens then upregulate FSH receptors (positive feedback).
When the corpus luteum regresses, what happens to oestrogen, progesterone and FSH?
Oestrogen/Progesteron decerase.
FSH increases.
At day 7 of the follicular phase, the dominant follicle secretes oestradiol and inhibin. How do these effect FSH and LH?
Oestradiol = inhibits FSH and LH Inhibin = inhibits FSH
When does positive feedback exceed negative feedback in the follicular phase?
When the level of oestradiol exceeds normal threshold for about 36 hours.
What are the effects of the oestrogen positive feedback?
Increase in GnRH
LH surge
Ovulation
What inhibits GnRH during the menstrual cycle?
When there is elevated levels of progesterone from the corpus luteum.
Before and after ovulation, which hormone dominates?
BEFORE ovulation - oestrogen
AFTER ovulation - progesterone
What is the “two cell, two gonadotropin” hypothesis?
That both LH and FSH are required for ovarian follicular maturation and the syntheses of ovarian steroid hormones.
LH promotes the production of androgens from THECAL cells (via testosterone and androstenedione).
The androgens then diffuse to the GRANULOSA cells where FSH stimulates the expression of aromatase, which converts the androgens to oestrogens.
Which hormone initiates steroidogenesis?
LH
What does LH stimulate in steroidogenesis?
cAMP to stimulate the activity of the (rate-limiting) cholesterol side chain cleavage enzyme.
What are the 3 growth differentiating factors (GDF) that may be involved in follicular recruitment?
GDF9
GDF9B
BMP15 (bone morphogenic protein)
Where does FSH bind to on oocytes?
Granulosa cells
What happens when the FSH threshold surpasses the normal threshold?
There is growth of some small antral follicles.
What effect does the oestradiol and inhibin (from dominant follicle) have on surrounding follicles?
Initially inhibits FSH that is insufficient for the surrounding follicles to grow -> atresia.
What hormone stimulates IGF-1 to be secreted from the granulosa cells?
FSH
What are the consequences of increased levels in IGF-1?
Increased cell proliferation and aromatase activity
thus,
OESTROGEN production through the roof.
What hormone regulates the conversion of cholesterol to pregnenolone?
LH
What does Propecia inhibit?
5a-DHT
Which two places are androgens produced?
Leydig cells
Adipose tissue
Where is oestriol produced?
Placenta
