Lec3 Male and Female Reproductive Endocrinology Flashcards
In males, what does the release of GnRH from the hypothalamus cause?
Release of LH and FSH from the pituitary
What does LH do in males?
Acts on the testes to cause secretion of testosterone
What does FSH do in males?
Acts on the testes to cause sperm production
Which hormones are needed for sperm production?
Both LH and FSH because sperm production requires testosterone
What effect does testosterone have on GnRH, LSH and FSH?
Testosterone negatively feeds back on GnRH, release of LH and FSH therefore reducing the secretion of these three hormones
What effect does inhibin have?
Inhibin produced by the testes negatively feeds back to the anterior pituitary gland to stop production of inhibin
What are the effects of testosterone?
They cause the male secondary reproductive characteristics: Increased aggression & libido Enlargement of the larynx Male pattern pubic hair Muscle development Sperm production Bone growth Acne
How is testosterone conversion to oestrodiol?
Aromatase
During pregnancy, the mother produces lots of oestrogen, what effect does this have on the baby?
No effect on the development of the baby
What happens in the male embryo?
The testes of the male embryo start to secrete testosterone, which causes development of male foetal anatomy
If there is no hormone activity, what happens to the foetus?
Then it is by default a female embryo
What is required for male anatomy to develop in the foetus?
Testosterone
If an XY embryo cannot produce testosterone, what will happen?
He will be born with female anatomy
What happens to males during puberty?
There is a dramatic increase in testosterone secretion to allow male secondary reproductive characteristics to develop
In females, what happens when the hypothalamus secretes GnRH?
There is LH and FSH secretion from the anterior pituitary gland
What is the effect of LH secretion?
LH secretion causes progesterone to be secreted from the ovaries (progesterone is a single hormone)
What is the effect of FSH secretion?
FSH causes the ovaries to secrete oestrogen (oestrogens are a group of hormones)
What are progestogens?
Progestogens are a synthetic hormone used in contraception and are progesterone-like
What effect do oestrogen and progesterone have on LH and FSH?
Oestrogen and progesterone negatively feedback to reduce FSH and LH secretion respectively
What are the effects of oestrogen?
Oestrogen do not influence development
An increase in oestrogen production in females causes development of secondary sexual characteristics
What are the female secondary reproductive characteristics?
Bone growth Female psyche Fair complexion Breast development Widening of the pelvis Maturation of genitalia Female pattern pubic hair Subcutaneous fat deposition Ovulation and menstruation
What happens to the levels of oestrogen in puberty?
There is a dramatic increase of oestrogen production in females which causes the development of secondary female characteristics
The hormones are cyclical - not constant level
What other effects can oestrogen have?
Development of maternal instincts is due to oestrogen
What happens to oestrogen in menopause?
Women stop producing as much oestrogen and progesterone and lose some secondary characteristics LH and FSH secretion increase due to the loss of the negative feedback
Which hormone is dominant in the first half of the menstrual cycle?
Oestrogen
Which hormone is dominant in the second half of the menstrual cycle?
Progesterone
Why does this occur where there is oestrogen dominance in the first half and progesterone dominance in the second half?
Due to GnRH pulsatility - pulsatile secretion of GnRH