Sex hormones Flashcards
- Define puberty
Maturation of Reproductive organs (ovaries and testes)
Production of sex-steroids E.g. Oestradiol/Testosterone Development of secondary sexual characteristics Attain capability to reproduce
- What is gonadarche, thelarche, menarche, spermarche, adrenarche and pubarche?
Gonadarche - Activation of gonads by HPG axis.
Thelarche - Onset of breast development Menarche - Onset of first menstrual cycle Spermarche - Onset of spermatogenesis Adrenarche - Onset of adrenal androgen production Pubarche - Onset of pubic hair
- What is the first sign of puberty in girls and boys respectively?
- What is often used to see what the testicular volume should be at each stage of life?
Girls - Thelarche
Boys - Testicular volume
Prader- Orchidometer
- Which hormones lead to the development of secondary sexual characteristics in boys and girls and what are the secondary sexual characteristics in boys and girls?
Girls
Oestradiol Breast development, hair growth (pubic+axillary), sweat gland composition - skin oiliness/acne and changes to external genitalia Boys Testosterone Deepening of voice, hair growth (Pubic then axillary+facial), sweat gland composition - acne/skin oiliness and changes to external genitalia
- Which hormones are produced by the adrenal glands that increase in concentration with age?
- What does gonadarche activate?
DHEAS/DHEA: Adrenal androgens
**HPG Axis** → Increase in LH and FSH
- Outline the HPG-axis
Kisspeptin neurones associated with the hypothalamus regulate the pulsatile secretion of GnRH
From parvocellular hypothalamic neurones into the primary capillary plexus within median eminence
Enters the portal-hypophyseal pituitary circulation
GnRH stimulates the release of LH and FSH from gonadotrophs in anterior pituitary within the HPG.
These hormones stimulate the ovaries and testes to produce testosterone and oestrogen
- How would you describe normal GnRH secretion?
- What is mini-puberty?
- What is precocious puberty and is it more common in girls or in boys?
Pulsatile secretion
The early/initial development and maturation of sex-organs Early puberty (<8yrs)
- What is the difference between primary and secondary amenorrhoea?
Primary - Having your first menstrual cycle later than 16 years > Regarded as abnormal
Secondary - Irregular periods/anovulatory for first 18 months. Periods start, but then stop for at least 3-6 months (Essentially, primary is having late delayed menarche whereas the secondary is an adult not having menstrual cycles for at least 3-6 months)
- What is the most common physiological cause of secondary amenorrhoea?
- What is oligo-menorrhoea?
Pregnancy
Irregular or infrequent periods >35 day cycle OR 4-9 cycles in total per year.
Outline the menstrual cycle
Follicular phase: FSH levels rise leading to the growth of 2-3 follicles. Then E2 and inhibin are produced, which reduce FSH levels via a negative feedback loop and restrict the ‘FSH window’. Non-dominant follicles undergo atresia (die) due to lack of FSH.
Follicular phase (Pre-ovulatary phase): Dominant Graafian follicle emerges. E2 continues to increase due to switch to a positive feedback system by high E2 inducing LH surge causing ovulation. Induction of LH stimulates ovulation, secretion of mature secondary oocyte from the Graafian follicle → Remnant follicle = Corpus luteum.
Luteal phase: Corpus luteum development through LH secretion→ secretes progesterone to maintain the endometrium lining. Progesterone level test for mid-luteal to identify ovulation. Decreases negative feedback effect, subsequently increasing FSH levels. Oestradiol is also secreted.
Corpus luteum degrades due to absent HCG stimulation → Shedding of endometrium lining → Menstrual cycle restarts.
- What happens in pregnancy that is different to a normal Menstrual cycle?
- What does continuous non-pulsatile administration of GnRH cause?
Beta hCG secretion → Activates FSH and LH receptors → Continues to support the corpus luteum → Secretion of progesterone
Decrease LH and FSH secretion → Decreased oestradiol and testosterone
- Outline GnRH pulsatility during the follicular and luteal phase of the Menstrual cycle.
During the follicular phase, GnRH pulsatility stimulates increased release of FSH for follicular development of Graafian follicle (Every 90-120 minutes)
Mid-cycle LH cycle due to positive feedback exertion of E2 → Increased pulsatility Luteal phase: Negative feedback of progesterone therefore decreases pulsatile effect of GnRH
- What is the difference between primary and secondary hypogonadism?
Primary - Gonads aren’t releasing their respective hormones hence Low E2/Testosterone and High FSH/LH (due to negative feedback loop in HPG axis)
Secondary - Low LH/FSH leading to low E2/testosterone
- What can cause primary hypogonadism in men?
- What is the commonest physiological cause of primary hypogonadism in women?
- A rise in which hormone can cause secondary hypogonadism?
Men - Infection, trauma, cancer of testes
Menopause Prolactin (prolactinoma formation or drugs used for psychiatric treatment)
- What are the symptoms of menopause due to a lack of oestradiol?
Skin dryness/Hair thinning
Hot flushes/Sweating/sleep disturbance Mood disturbance Osteoporosis Sexual dysfunction Weight gain Amenorrhoea Cessation of fertility Climacteric - Irregular periods in years close to Menopause
